Atlas of Fish Histology
and Histopathology
Galit Sharon and Dina Zilberg
Funded by JCA Charitable Foundation,
Ramat Negev and Central and Northen
Arava Research and Development Centers
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Table of contents
1.
Fish Anatomy…………………………………………………....2
2.
Histology of Different Fish Species………………………….14
Guppy, poecillia reticulate……………………………………15
Molly, Poecilia velifera………………………………………...26
Freshwater angelfish, Pterophyllum scalare……………….34
Australian Sea Bass, Lates calcarifer, Barramundi………..42
3.
Histopathology…………………………………………………54
Tetrahymena spices…………………………………………..55
Ichthyophthirius multifilis……………………………………..61
Hexamita and Spironucleus…………………………………63
Nematoda……………………………………………………..64
Granuloma…………………………………………………….65
Lymphocystis………………………………………………….66
Muscle dystrophy……………………………………………..67
Spondylopathy………………………………………………...69
Liposarcoma and Leoma…………………………………….70
Squamous cell carcinoma-SCC…………………………….75
Liver apoptosis………………………………………………..76
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Fish anatomy
Circulatory system:
Consists of: blood vessels, heart, fluids and blood cells.
Other involved organs: spleen, kidney and thymus. These are involved in
production of new blood cells and destruction of blood cells.
Heart:
Teleost heart consists of two chambers and two other distinct regions:
The two chambers are Atrium and Ventricle (chambers); Bulbus arteriosus
and Sinus venosus. The atrium and ventrical are seperated by paired semilunar valves.
The heart is positioned above the liver.
Blood Flow in the heart:
Venous blood
(None oxidized, from hepatic and common cardinal veins)
Sinus venosus
Atrium
Ventrical
(Pumping action of heart, two layers of cardiac muscle)
Bulbus arteriosus
(Elastic connective tissue and smooth muscle. Regulates blood pressure,
prevents back flow and regulates flow to delicate gills)
Spleen:
The dark red disk shaped organ is located between the fundic stomach and
swim bladder and it is attached to the hepatic portal vein.
Composed of two distinct regions:
Red pulp- storage of mature erythrocytes.
White pulp- Leucocytes- antigen presentation, lymphocyte proliferation and
removal of effected RBC, waist material and pathogens.
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Thymus:
The thymus is located in the dorsal portion of the opercular cavity. This is the
site of T-lymphocyte maturation.
Blood cells:
Red blood cells (RBC) - Erythrocytes, most abundant cells in the blood. In fish
they are elliptical with a central oval nucleus. Contain hemoglobin for O2
binding and transfer.
White blood cells (WBC) - Leukocytes and Thrombocytes, responsible for
immune responses, getting rid of foreign material and blood clotting.
Kidney:
Head Kidney- Hematopoietic organ and endocrine tissue. The head kidney is
located anterior to the swim bladder.
Trunk kidney- Hematopoietic tissue and functional kidney.
Digestive system:
Consists of an alimentary tract (oral cavity, pharynx, esophagus, stomach and
intestine and accessory digestive organs (pancreas, liver and gall bladder).
Different fish species have different structures of digestive organs; this is
related to the phylogeny of the fish and the type of food they eat.
Mouth varies by location and structure, stomach may be absent and gut
length varies.
Oral cavity:
Mouth position- Superior: feeds at the surface or utilizes oxygen in air-water
interface. Terminal and inferior: fish that feed on the bottom.
Oral teeth - positioned on the jaws for catching and holding the prey.
Pharyngeal teeth - grinding food before swallowing.
The pharynx is a part of the digestive system and of the respiratory system
(contains the gill rakes).
Esophagus:
The esophagus connects the pharynx to the stomach (or to the intestine when
stomach is absent).
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Stomach:
Size and shape varies in different groups of fish (for example in larvae and
cyprinids it is absent).
It is J shaped with 2 distinct regions:
Fundic region- large folds, mucosa is thick and contains gastric glands in the
lamina propria.
Pyloric region- no gastric glands.
The stomach holds food during the early stages of digestion and? secrets
digestive enzymes (hydrochloric acid, pepsinogen)
Intestine:
Intestine varies in length and arrangement in the body cavity between fish
species (>1 int. length /fish length in carnivorous and >20 int. length /fish
length in herbivorous).
The mucosa of the intestine forms folds and microvili, which increases the
surface area for better absorption.
Proximal intestine- is the primary site of lipid absorption- resaving enzymes
and bile from pancreas and gallbladder.
Middle intestine- has active pinocytosis, related to uptake of macromolecules
(proteins and carbohydrates).
Rectal intestine- has no role in absorption.
Liver:
The main liver structures include sinosoides which supply blood to liver cells
(hepatocytes) and bile duct which collects the bile produced in the
hepatocytes.
Liver functions are intermediate metabolism, bile production and the synthesis
of several proteins secreted into the blood.
Hepatocytes are also important sites of glycogen and lipid storage.
The liver is divided into two lobules.
Gall bladder and Bile production:
Bile produced in liver hepatocytes travels through the bile duct and cystic duct
to the gall bladder, where it is stored.
When fish feed, a sphincter in the common bile duct opens and bile is
released from the bladder into the intestine.
Pancreas:
There are two unrelated types of tissues in the pancreas:
1) Islets of endocrine cells, secreting different hormones (such as insulin).
2) Exocrine glands, producing digestive enzymes, trypsin, chymotrypsin,
amylase and carboxypeptidase.
The pancreatic ducts connect the acinar glands to the intestine.
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The teleost's pancreatic tissue is disseminated and can be found within the
mesenteries of the peritoneal cavity and in some species within internal
organs, such as liver, spleen.
Swim bladder:
The swim bladder is located ventrally to the spinal cord, dorsal to the kidney.
Its primary function is hydrostatic regulation, but it may also serve for sound
production, respiration and pressure detection.
Hydrostatic regulation - positioning in the water and reducing the fish's
specific gravity.
Sound - producing sound by releasing gas through the pneumatic duct and
vibration of the swim bladder wall. Improvement of hearing in some fish
species, as sound is transmitted from swim bladder to the ear.
Respiration- was the primary function of this organ; an open pneumatic duct is
required for efficient gas exchange between the environment and the swim
bladder.
Pressure detection- the swim bladder is a pressure detector.
There are two types of swim bladders:
Physostomous- (lung like organ) pneumatic duct is functional in adults.
Physoclistous- pneumatic duct is absent in adults. True physoclistous have no
pneumatic duct from larval stage; while transient physoclistous initially have a
pneumatic duct which degenerates with fish maturation.
Endocrine system:
Endocrine glands releases substances called hormones into the blood.
The organs involved in secretion of hormones are many, discussed here are a
few- head kidney, pancreas and pituitary gland.
Head kidney:
This part of the kidney consists of hemopoeietic, interrenal and chromaffin
tissues.
The interrenal and chromaffin tissues are homologous to mammalian adrenal
gland. Interrenal cells release corticosteroids; chromaffin cells release
catecholamines, adrenalin and noradrenaline.
Stress conditions and environmental stimuli that fish perceive to be harmful
often cause the release of hormones from both these endocrine tissues.
Pittuitary:
This gland has an important function: it controls other endocrine glands.
There are two basic parts of the pituitary gland:
Neurohypophysis- The core of the pituitary gland, composed of primary nerve
fibers that originate in the brain. This part releases hormones that are
responsible for reproduction and osmoregulation. The most important role of
the neurohypophysis is to control the adenohypophysis.
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Adenohypophysis- This part can be divided into: pars distalis and pars
intermedia. In each region there are different cell types that secrete different
hormones that are responsible for: osmoregulation, stimulation of the interrenal cells in head kidney, stimulation of growth, regulation of thyroid gland,
gametogenesis and gonadal maturation and darkened coloration
(melanophores).
Pancreatic Islets:
In teleosts the pancreas is usually disseminated in the anterior body cavity.
There are four types of hormone secreting cells that are responsible for
controlling blood glucose and tissue glycogen levels.
Excretory system:
In fish both the kidney and gills may be excretory organs.
The two functions of the excretory system are:
1. Excretion of nitrogen wastes, in the form of ammonia and urea.
2. Regulation of water and ion balance- osmoregulation.
Kidney:
The trunk kidney functions as part of the excretory system, but it may also
have hematopoietic tissue. Trunk and head kidney are not grossly
distinguishable.
The functional units in the trunk kidney are nephrons, their function is to filtrate
the blood, retention and reabsorption of water, hormones, nutrients and
excretion of other substances into the renal lumen. The filtrate is called urine
and is released to the urinary bladder.
Urinary bladder:
This organ is present in the posterior part of the body cavity.
Osmoregulation in freshwater fish- the aquatic environment has a lower ionic
strength than the fish's body fluids. Thus, water passively enters the fish and
salt is lost. In the kidney: production and excretion of high volume of urine with
low salt concentration. Salts are obtained from food.
Osmoregulation in marine fish- the aquatic environment has higher
concentration of salts the the fish's body fluids. Thus, water passively leaves
the fish. To compensate for the loss, fish actively drink water. Salt passively
enters the fish and is also absorbed through the alimentary tract. In the
kidney: concentration of urine and reduction of urine fluid (fewer or smaller
glumeroli), reabsorption of water. Salts are secreted through the urine, gills
and digestive tract.
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Respiratory system:
The principal respiratory organs of most fish are the gills.
Gills:
There are four pairs of fully developed gills, four on each side. They extend
from the dorsal wall to the ventral wall of the pharynx. The gill arch attaches
the gills to the pharynx and supports the other parts of the gills; it is usually
made of cartilage. The gill rakers protect the gill tissue and capture food. From
each gill arch two rows of filaments extend into the opecular cavity. They are
the skeletal support and are mainly made of cartilage. Each filament has
lamellae extending from both sides. The filaments have muscles attached to
their base so their orientation can change according to water current. The
filaments contain blood vessels and sinusoids for gas exchange (with
surrounding water).
The function of the gills:
1) Gas exchange (O2 and CO2) between blood and water, mainly in the
lamellae and filaments.
2) Excretion of nitrogenous waste (excreted as ammonia in teleosts), mainly
through gill epithelium.
3) Gills are also part of the excretory system. Ions such as sodium, chloride,
carbonate, hydrogen and calcium are transferred through the gills between
the water and blood.
Pharyngeal water flow:
In the pharynx, water flows through the mouth and over the gills. Pharyngeal
water flow is achieved from either ventilation or pumping. Ram ventilation is
when a fish swims with the mouth open so water is forced through the gills.
Pumping is a mechanism which involves alternating expansion and
contraction of the bucal and opercular cavities. Water flows into the mouth
and then expelled from the opercular opening. The respiratory pump
mechanisms depend on fish's species and its activity.
Nervous system:
The nervous system usually uses signals transmitted by nerves. It also has
sense organs that receive input from the environment and other organs in the
body. Impulses from sense organs travel to the central nervous system where
information is interpreted. The main difference between fish nervous tissues
and mammals is that in fish there is a continuing growth of these tissues.
The CNS (central nervous system) is surrounded by three layers which are
termed the meninges. These layers have an important function in defense and
maintaining the outer blood-cerebrospinal fluid barrier. In teleosts the
meninges have an additional function, to produces secretory proteins that play
a predominant role in neuronal regeneration.
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Brain:
Teleost brain accounts for 0.3% of the body weight. It can be divide into three
main areas: Forebrain, Midbrain and Hindbrain, all of which contain 5 main
region
Forebrain
Telencephalon- contains the paired olfactory lobes, bulbs and the cerebrum,
which in fish consists of interconnected fields of neurons.
Diencephalon- this region of the brain is a primary site of coordination center
between different regions of the brain and between brain and the pituitary and
pineal glands.
It is the site of the pineal body which detects slowly changing ambient light
level for photic control of sensorial physiology.
The Hypothalamus is the major anatomic structure in this site; it regulates the
pituitary gland.
Midbrain
Mesencephalon- is the largest region; composed of the paired optic lobes.
Their function is important for vision.
Hindbrain
Metencephalon- is composed mainly of the cerebellum, it receive stimuli from
the lateral line and ears. It's function is mainly in swimming, equilibrium,
maintenance of muscular tone and orientation.
Myelencephalon- is composed of the medulla oblongata, important in the
function of the reticulomotor system, taste and audition.
The paired facial and vagal lobes are included within this region. The vagal
lobes stimulate chemoreceptors in the oral cavity, gills and skin of the head.
The facial lobes stimulate cutaneous chemoreceptors.
The medulla oblongata continues caudally and becomes the spinal cord.
Spinal cord:
The spinal cord is located within the neural arches on the dorsal side of the
vertebrae. The nerves located within the spinal cord are separated into gray
matter and white matter that form dorsal and ventral horns. There is a small
central canal located in the spinal cord.
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Sense Organs:
Eye:
The fish eye mechanism of function is different from the mammalian eye. The
retinal portion of the eye produces nerve impulses in response to light. In the
retina there are light sensitive cell (rods for darkness and cones for bright
light), the light enters the eye and is focused by the lens. The iris in most fish
is not contractile.
Blind spot
11Retina
Diagrammatic representation of there eye (After Walls
1942 as sighted in Roberts 2001)
Ear:
The ear is divided into two parts:
1) The superior part which functions in maintaining equilibrium. This part is
composed of the semi lunar canal and utriculus.
2) The inferior part is probably involved in hearing and it is composed of the
lagena and sacculus. The sense receptors are located within the ampullae of
the ear. In teleosts there are otooliths associated with them.
Lateral line:
The lateral line is only found in fish and aquatic amphibians. The lateral line
canal often extends on the lateral body from the caudal peduncle to the head
where it branches to various regions of the head. The canal is located in the
dermal or epidermal layers of the skin. The lateral line has pores that connect
it to the body surface. The lateral line's function is to detect low frequency
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vibrations in the water. This includes swimming fish and "distant touch" by
which objects in the water can be detected by vibration reflected from them.
Ampullary Organ - Organs found in the skin of fish and seem to be related to
the lateral line. They function as electroreceptors in many species; some
species of fish can generate sufficient electrical charge to stun prey, enemies
or to locate objects. Other species use them as sense organs to detect
muscular movement and therefore the presence of other animals.
Olfactory organ:
This organ is responsible for the smell sense. There is usually one or two
nares connected to a nasal sac. The smell and taste senses are not clearly
separated in aqueous environment. The major functions of the olfactory organ
includes: Guiding migratory fish to a home stream, location of home range in
territorial species, detection of alarm substances, detection of pheromones
that control social interaction.
Taste buds:
This are most commonly found on lips, barbells, oral and pharyngeal mucosa
and gill arches. Some are found also on external body surfaces in some
species. Their function is detection of food.
Reproductive system:
The reproductive system includes the gonads and the ducts. The gonads
produce the gametes (eggs or sperm) and they are endocrine glands. Factors
affecting the function and structure of the fish reproductive system are: 1)
number of offspring’s produced per spawning 2) type of fertilization (external
or internal) 3) degree of bisexuality.
Male reproductive system- The testes are in the body cavity and are usually a
paired organ (they can be fused or only one testes will develop in some
families). The anterior region consists of sperm-producing tissue; the posterior
region is composed of glandular tissue with unknown function. The testes are
composed of seminiferous tubules. There are a few types of cells; Sertoli cells
hold developing sperm cells and interstitial cells of the testis are a primary
source of androgens. Sperm is produced in the seminiferous tubules and
collect in the lumen of the tubules and sperm duct until mating occurs.
Female reproductive system- The ovaries are separated in the body cavity by
mesenteries called mesovarium. Ovaries may be paired or fused. The ovaries
in fish produce large numbers of eggs, and occupy much of the body cavity.
There are three basic types of ovary-duct arrangements: 1) gymnoarin- ova
are shed from the ovary into the coelom then pass down the oviduct where it
is enveloped by nutritive and protective covers, until reaching the uterus,
which contains the embryo during development. 2) cystoarian- ovary develops
with a lumen continuous with the oviduct. Ova are shed unto the lumen and
go through the oviduct. 3) Secondary gymnoarian- Ova are shed in to the
coelom and then enter a short oviduct.
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Integument:
Skin:
The skin protects against the environment, including pathogens, toxicants and
excess water and ion flux. The skin also protects against mechanical injury
and predators (in fish with thick scales or dermal plates). Thickness of the skin
is usually dependent on the species of fish and the types of scales present.
Fish without scales have thick epidermis (greater then 100 µm) than do fish
with scales.
Epidermis - outer skin layer. Mostly is a source of new cells. There are
generally no blood vessels in the epidermis.
Dermis - the thickest and most prominent layer of the skin. The scales (if
present) are located in the dermis. The dermis provides strength for the skin
and contains nerves and blood vessels. The dermis also contains pigment
cells and the lateral line.
Scales- There are several types, the most common are: A. Placoid- tooth-like
scale, made out of vitreodentine (like enamel) and dentine. B. bony ridge- it
has a thin, translucent layer of fibrous connective tissue covered by bony
ridges that form the circuli.
Glands:
The multicellular axillary glands are located beneath the skin dorsal to the
pectoral fin. There are thick septa which divide the gland into lobes.
Fins:
The fins are covered by skin. The pectoral and dorsal fins have a hard ray or
spine; the caudal, pelvic and anal fins have no spine present. The fins (except
for the adipose fin) have epidermis and a compact layer of dermis. The
adipose fin is composed of loose fibrous connective tissue covered by skin.
Fins have specialized skeletal muscles for movement and are arranged in
pairs.
Musculature:
The function of the muscles include locomotion, movement of water across
the gills, sound production, circulation of blood, movement of food through the
alimentary canal, rotation of the eye, expulsion of gametes from gonads and
contraction of the urinary bladder. All muscles consist of fiber-shaped cells
that shorten as a result of interaction between actin and myosin filaments.
Types of muscles:
Skeletal - most are used for skeletal movement and are under voluntary
control. They have striation in their fibers and each fiber has several
peripherally located nuclei. Lateral skeletal muscles of fish can be
distinguished as either red or white muscle. Red muscle – contract more
slowly, and used for slow, cruising speed when aerobic metabolism of fat is
used for energy. White muscle - utilizes anaerobic glycolysis for energy and is
2 AA
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used for short periods of rapid swimming. The proportion of red and white
muscles depends on the type of swimming.
Smooth - the muscle fibers have one centrally located nucleus, they cause
movement of visceral organs and they are not under voluntary control.
Cardiac – this muscle is found only in the heart. The fibers are similar to
skeletal muscle except for being branched and having a centrally located
nucleus.
Skeletal system:
The skeletal system consists primarily of bone and hyaline cartilage.
Skull:
The skull is composed of several bones that are fused or tightly joined
together.
Visceral skeleton:
This includes the branchial arch which supports the gills and mandibular and
hyoid arches.
Vertebral column and ribs:
The vertebrate can be classified as caudal or trunk, each vertebrate is
different. In the posterior trunk vertebrate the transverse processes extend
laterally, 9-11 vertebrate bear pleural rib.
Fins:
All the fins are supported by a skeletal element except for the adipose fin.
Bone:
Bone formed with association to the dermis is direct bone formation.
Perichondral ossification of hyaline cartilage is indirect bone formation.
Skeletal elements have a core of cartilage surrounded by bone. The space
within the bone contains blood vessels and connective tissue.
Notochord:
This unique tissue is located in the center of the vertebrate it is much more
prominent in juveniles than in adults; it compresses by each vertebrate and
expands near the junction of the adjacent vertebrate. Only the cell membrane
and nuclei of the notochordal cells are visible.
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Hyaline cartilage:
This tissue forms a large portion of the skeleton in small fingerlings and parts
of the adult skeleton remain cartilaginous. Cells are separated by variable
amounts of clear matrix.
Pseudo cartilage strips are found only around the mental and mandibulary
barbells.
Gill-filament cartilage:
It is similar to other cartilage but there is less matrix between cells than in
hyaline cartilage and the matrix is more acidophilic.
Chondroid:
Primitive type of cartilage found in the opercular bone, hypuralsof the caudal
fin and other locations.
References
Grizzle M. J., Rogers A.W., 1976. Department of Fisheries and Allied
Aquacultures: Rouse D.R., director, Anatomy and Histology of the Channel
Catfish. Copyright 1976 by Auburn University Agricultural Experiment Station.
Auburn Printing, Inc. Auburn, Alabama, pp 5-85.
Genten F., Terwinghe E., Danguy A., 2009. Department of Histology
and Biopathology of Fish Fauna Laboratory of Functionnal Morphology: Atlas
of Fish Histology. Published by Science Publishers, Enfield, NH, USA. An
imprint of Edenbridge LTd., printed in India, pp 1-145.
2 A3
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Histology of Different Fish
Species
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Guppy, poecillia reticulate
11
Mouth
Spiny, Soft
11Dorsal Fin
Caudal Fin
(Tail)
Operculum
11(gill cover)
11Pelvic Fins
Pectoral
11Fins
11
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Fish origin: South America: Venezuela, Barbados, Trinidad, northern Brazil
and the Guyanas. Widely introduced and established elsewhere.
Climate: Tropical; 18°C - 28°C
Environment: non-migratory; freshwater; brackish water; water pH range: 7.0
- 8.0; wide salinity range.
Fish Characteristics: Occurs in warm springs, weed ditches
and canals. Found in various habitats, ranging from highly
turbid water in ponds, canals and ditches at low elevations to
pristine mountain streams at high elevations. Feeds on
zooplankton, small insects and detritus.
Guppy are live bearers. Males sexually mature around the age of 2 months
and females at round 3 months of age. Females can reach 5 cm in length but
males stay smaller.
A very popular and widely available species in the aquarium trade and many
standardized varieties are established. This species is used in genetics
research.
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11Histology of the different systems:
Circulatory system:
Blood cells:
a
b
11R
N
P
11R
E
Figure 1: Blood cells from a blood smear (Dip quick). a) red blood cells (R), white blood
cell-Neutrophil (arrow-N) and Platelets (P); Bar= 10µm. b) red blood cells (R), Immature
erythrocyte (arrow-E); Bar= 10µm.
Hart:
11
11
11
11
11
11
11
11
11
11V
11
11
11
11
11
Figure 2: Heart parenchyma showing arrangement of cardiac muscles; (V) ventricle and;
Bar= 10µm.
11
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11Spleen:
P
L
11
11w
11R
11
11
Figure 3: spleen with red (R) and white (W) pulp. Bar=50µm.
11
Digestive system:
Stomach:
11
11
11
11
11
11
11
11
11
11
11
11
11
11
L
11
11
11Figure 4: (S) stomach featuring short microvilli (arrow), (L) liver; Bar=50µm.
11
11
11
11
11
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Intestine:
11
11 a
11
11
11
11
11
11
11
11
11
11
11
11
11b
I
I
I
11F
11F
11M
11E
Figure 5: a) (I) Small intestine - transverse section; Abdominal adipose (fatty; F)
tissue in the body cavity, surrounding the intestine; b) The mucosa can be seen,
including microvilli (arrows), columnar epithelium (E) and muscularis mucosa (M); a)
Bar=50 µm. b) Bar=10 µm.
Rectum:
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
Ad
11R
M
Figure 6: Rectum showing rectal foldes (R), rectal orifice-Anus (arow), muscle (M)
and adipose tissue (Ad); Bar=50µm.
11
11
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Oral cavity:
11
T
E
OG
Figure 7: Oral cavity showing teeth (T), oral glands (OG) and eousophagus
11(E);Bar=50µm.
11
11
11
11
Liver:
11
11
a
11
b
11
11
11
11
11
H
11
H
11
H
11
11
11
11
11
11
11
Figure 8: Liver tissue composed of hepatocytes (H); blood vessels (arrow), a)Bar=50µm,
b)Bar=20µm.
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11
11
Pancreas:
11
11111111111111
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11
11
11
11
11
11
11
11
11I
11P
11P
11F
11P
Figure 9: pancriatic tissue cells (P) serrawnded by adipos fat (F); blood vessels
(arrow), and Intestinal tissue (I); Bar=10µm.
111
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1
11
11
11
11Swim bladder:
11
11
11
11
11
11
11
11
11
11
11
11
11Figure 10: Abdominal cavity showing inflated swim bladder (arrows), Bar=50 µm.
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Endocrine system and excretory system:
Kidney:
11
b
a
11HT
G
11HT
G
Figure 11: a) Head kidney showing renal tubules (arrows), hematopoetic tissue (HT)
and renal corpuscle with its glomeruli (G); Bar=10 µm. b) Trunk kidney showing more
renal tubules (arrows) and little amount of hematopoietic tissue (HT); Bar=200 µm.
11
11
Urinary blabber:
11
1
11
1
11
11
11
Figure 12: Distended urinary bladder showing very few mucosal folds (short arrow) and a
longitudinal section of one of the urethras (long arrow); Bar=10µm.
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Respiratory system:
Gills:
b
a
11
11
GO
11
Figure 13: Gills, showing:gill operculum (GO); gill filaments (short arrow); gill lamellae (long
arrow); a) Bar= 20 µm. b) Bar= 5 µm.
11
11
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Nervous system:
Brain:
a
b
11
Cer
Cr
Cr
OpL
Cer
OL
OL
M
11
11
Figure 14: Brain showing olfactory lobe (OL); optic lob (OpL); cerebellum (Cer);
cerebrum (Cr); Medula oblongata (M). a) Bar=10 µm; b) Bar= 500µm.
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Spinal Cord:
11V
G
11N
11
W
11A
11N
11VC
Figure 15: spinal cord showing: Grey matter (G); White matter (W); vertebra (V);
Notochord (N); Large vacuolated cells filling the center core of the notochord
providing the notochored its flexibility (VC); Axons of Mauthner neurons (bifurcated
arrows); Dorsal artery (A). a) Bar= 1002m; b) Bar=502m.
Sense Organs:
Eye:
AC
11
11
11
11
11
11
11
11
11
11
L
AC
R
O
Figure 16: Eye showing: lens (L), retina (R), aqueous cavity (AC); iris (short arrow);
cornea (long arrow); and optic nerve (O); Bar= 50µm.
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Ear:
11O
11
11
11
11
O
11
11Figure 17: Inner ear showing otolith chambers (O) area; Bar= 100µm.
Reproductive system:
11111
Female reproductive system:
11
11
11
11
11
11
11
11
O2
11
11
11
11
11
11
O2
O3
Figure 18: female gonads showing oocytes in different stages of development (O2stage IV, O3- stage V); Bar=50µm.
11
11
3
8B
Fetus:
11
11
B
11
E
11
K
11
11I
11
I L
11
Y
11
11
11
11
V
11
11
Figure 19: Guppy's Fetus showing: yolk sac (Y); vertebral column (V- short arrows);
intestine (I); kidney (K); liver (L); spinal cord (arrow); brain (B); eye (E); Bar= 50 µm.
Integument:
Skin:
11
11
11
M
11ED
11D
11
11
11
11
11
Figure 20: skin showing: skeletal muscle tissue (M); dermis (D); Epidermis(ED);
11Bar=200 µm.
11
3
82
Molly, Poecilia velifera.
1
1
Spiny, Soft
Dorsal Fine
11Mouth
Caudal
Fin (Tail)
11Lateral line
Operculum
11(gill cover)
11Pectoral Fins
11Pelvic Fins
Fish origin: central America- Yucatan, Mexico
Climate: Tropical, 25-28°c
Environment: Water pH range- 7.5-8.5, Fresh water and brackish water.
Fish Characteristics: Adult size can reach 10-15cm, usually much smaller. It
is a peaceful fish, omnivore and algae eater. Molly is a live bearing fish which
are hared to breed.
3
84
Histology of the different systems:
Circulatory system:
Hart:
11b
a
A
V
Figure 1: Heart tissue: a) Heart parenchyma - arrangement of cardiac muscles. b)
Cardiac valve (arrow) separating between the atrium (A) and ventricle (V); Bar= 0.05µm.
P
L
Spleen:
11R
W
3
85
Figure 2: spleen with red (R) and white (W) pulp. Bar=0.05µm.
Thymus:
b
a
T
T
11M
Figure 3: Thymus (T). a) blood vessele (arrow), Bar= 0.1µm. b) Muscels tissue (M) surrounding
the thymus; Bar= 0.05µm.
Digestive system:
Intestine:
11a
E
11M
3
86
Figure 4: Small intestine ( transverse section). The mucosa can be seen, including
microvilli (arrow), columnar epithelium (E) and muscularis mucosa (M); Bar=0.02µm
Oral cavity:
11T
11OG
11OG
11T
1Figure 5: Oral cavity showing teeth (T) and oral glands (OG),Bar=0.05µm.111 111111
Liver and Pancreas:
b
a
11H
11P
11H
11P
11P
Figure 6: Liver tissue composed of hepatocytes (H); a) blood vessels (arrows),
Bar=0.05µm; b) pancriatic tissue (hepatopancreas; P ), Bar=0.1µm. 1
3
87
Endocrine system and excretory system:
Kidney:
Head kidney:
HT
Figure 7: a) Head kidney showing renal tubules (arrows) and hematopoetic tissue (HT);
Bar=0.02µm.
Trunk kidney:
HT
3
A9
Figure 9: Trunk kidney showing renal tubules (arrows) and hematopoietic area (HT);
Bar= 0.05µm.
Respiratory system:
Gills:
a
11
b
11
11
11
A
Figure 9: Gills, showing a) gill arch (A); filaments (arrow heades); b) gill lamellae (short
arrow), blood vessals (long arrow). A,b) Bar=0.05µm. 11
111
Nervous system:
Brain:
11
11OL
11ON
OpL
Cer.
3
A1
Figure 10:Brain showing olfactory lobe (OL); optic lob (OpL); cerebellum (Cer); optic
nurve(ON) Bar=0.05µm.
Sense Organs:
Eye:
a
b
11L
11AC
11L
11CA
11R
Figure 11: Eye shoeing: lens (L), lens capsule (LC; arrow), retina (R), aqueous cavity (AC)
a) Bar=0.2µm; b) Bar= 0.05µm.
Reproductive system:
Male reproductive system:
11a
b
11TL
11TL
F
3
A8
Figure 12: mail gonades: testis lobes (TL-arrows), fat tissue (F); a) Bar=0.05µm b)
Bar=0.02µm.
Female reproductive system:
11a
b
O2
O1
1
O1
1
O3
11O1
11c
O3
O3
O3
Figure 13: female gonads showing oocytes in different stages of development (O1-stage III,
O2- stage IV, O3- stage V). a) Bar=0.05 µm b) Bar= 0.05 µm c) Bar=0.05 µm.
3
AA
Freshwater angelfish, Pterophyllum scalare
Spiny, Dorsal
Fine
Caudal
Fin (Tail)
11Mouth
Operculum
11(gill cover)
Branched Ray
11Fins
11Pectoral Fins
Spiny, Anal
11Fins
Fish origin: South America: Amazon River basin, in Peru, Colombia, and Brazil,
along the Ucayali, Solimões and Amazon rivers; rivers of Amapá (Brazil), Rio
Oyapock in French Guiana; Essequibo River in Guyana.
Climate: Tropical; 24°C - 30°C.
Environment: freshwater; pH range: 6.0 - 8.0.
Fish characteristics: Body compressed and disc-shaped; dorsal and anal spiny rays
increasing in length from anterior to posterior part of the fin; first branched rays also
very long. It inhabits swamps or flooded grounds where the aquatic and riverine
vegetation are dense (stream banks and next to the springs) and the water is either
clear or silty. The fish color is deeper in clear water. Its maximum length is 15 cm.
1112
Histology of the different systems:
Circulatory system:
Heart:
b
a
11V
V
11P
11G
11A
SV
A
Figure 1: Heart parenchyma showing (V) ventricle and (A) atrium, Pericardium (arrow),
pericardial cavity(P) and sinus venosus (SV); gills (G); a) Bar= 20µm b) Bar=200 µm.
Spleen:
W
W
R
R
Figure 2: spleen with red (R) and white (W) pulp; Fibrous capsule (arrow); a) Bar=100 µm
b) Bar=50µm.
1113
Digestive system:
Oral cavity:
E
M
T
Figure 3: Oral cavity showing teeth (T), eosophagus (E), mucosal epithelial cells (M);
Bar=50µm.
Stomach and Intestine:
SI
LI
S
Figure 4: (S) stomach featuring short microvilli, (SI) small intestine and (LI) large intestine;
Bar=200 µm.
1114
Liver and Pancreas:
b
a
H
L
L
P
P
Figure 5: Liver lobes(L) composed of hepatocytes (H), blood vessels (arrows) and
hepatopancreas, surroundeing the blood vesselcells (P); a) Bar=100 µm b) Bar=200 µm.
Swim bladder:
11TK
I
Figure 6: Abdominal cavity showing inflated swim bladder (arrows), Intestine (I) and Trunk
kidny (TK); Bar=50 µm.
1115
Excretory system:
Kidney:
V
TK
I
L
HK
I
Figure 7: Abdominal cavity featuring (HK) Head kidney, (TK) Trunk kidney, (I) Intestine, (V)
vertebra Colum and (L) liver; Bar= 200 µm.
.
Head kidney:
HT
Figure 8: Head kidney showing hematopoetic tissue (HT) and renal tubules (arrow);
Bar=500 µm.
1116
Trunk kidney:
T
G
T
T
HT
HT
T
T
T
T
T
T
Figure 9: Trunk kidney showing renal tubules (T), hematopoatic tissue (HT), renal glomeruli
(G) and Renal capsule (arrow); Bar=50 µm.
Note: the relatively little amount of hematopoietic tissue and abundance of renal tubules,
compared to the head kidney.
Gills:
b
a
BV
A
Figure 10: Gills, showing gill arch (A); gill filaments (long arrow); b) gill lamellae (short arrows);
blood vessals (BV). a) Bar=200 µm; b) Bar=100 µm.
1117
Nervous system:
Brain:
b
a
113
11OpL
111
Cer
11OpL
11Cer
11Cr
11OL
Sc
11M
H
11OpL
11H
2
Figure 11:Brain showing (1) Telencephalon: cerebrum (Cr); olfactory lobe (OL). (2)
Diencephalon: Hypothalamus (H); (3) Metencephalon: cerebellum (Cer); Optic lob (OpL). Spinal
cod(Sc); Medula oblongata (M). a) Longitudinal cut, Bar=500µm. b) Transverse cut, Bar=10 µm.
Spinal Cord:
b
a
N
A
V
W
SC
G
Figure 12: spinal cord showing: Grey matter (G); White matter (W); vertebra column (V);
Notochord (N); Spinal cord in the vertebral canal (SC); Axons of Mauthner neurons (bifurcated
arrows); Dorsal artery (A). a)Transverse cut, Bar= 100 1m; b)Longitudinal cut, Bar=500 1m.
1128
Sense Organs:
Eye:
a
b
O
L
AC
R
Figure 13: Eye showing: lens (L), retina (R), aqueous cavity (AC); iris (short arrow);Lens capsule
( arrow); Optic disc where the optic nerve leaves the retina ("blind spot") (circle) and optic nerve
(O); a) bar=100µm. b) Different layers of the Retina, choroid and sclera, bar=200 µm.
Ear:
a
b
O
O
O
O
C
O
C
O
Figure 14: Inner ear showing otolith chambers (O) area, sensory area (crista ampullaris) rising
from the wall of the ear canal (arrows) and Ear hyaline catilage (C); a) Bar=100 µm. b) Bar=100 µm.
1129
Australian Sea Bass, Lates calcarifer, Barramundi
Dorsal
11Fins
11Caudal
Fin (Tail)
11Mouth
Operculum
(Gill Cover)
Pectoral
11Fins
Pelvic
11Fins
Anal
11Fin
Fish origin: Indo-West Pacific: eastern edge of the Persian Gulf to China, Taiwan
and southern Japan, southward to southern Papua New Guinea and northern
Australia.
Climate: Tropical; 15°C - 28°C.
Environment: Freshwater; brackish; marine water; depth range 10 - 40 m.
Fish Characteristics: Length at first maturity: 29 - 60 cm. Max length: 200 cm.
male/unsexed: 150 cm, male/unsexed; max. published weight: 60.0 kg.
Body elongate, mouth large and slightly oblique and the upper jaw extends behind
the eye. Lower edge of preopercle serrated, with strong spine at its angle. The
opercula has a small spine and with a serrated flap above the origin of the lateral
line. Caudal fin is rounded.
Biology: Found in coastal waters, estuaries and lagoons, in clear to turbid water.
The fish inhabits rivers before returning to the estuaries to spawn. It is a
hermaphrodite fish, larvae and young juveniles live in brackish temporary swamps
112A
associated with estuaries and older juveniles inhabit the upper reaches of rivers.
This fish has preference for cover on undercut banks, submerged logs and
overhanging vegetation. Barramundi feeds on fishes and crustaceans. They can
reach 1500-3000 g in one year in ponds under optimum conditions. Juveniles also
eat insects, sold fresh and frozen; consumed steamed, pan-fried, broiled and
baked. It is a very popular and sought-after fish of very considerable economic
importance. Presently used for aquaculture in Thailand, Indonesia, Israel and
Australia. This is Australia's most important commercial fish and one of the most
popular angling species.
Histology of the different systems:
Circulatory system:
Heart:
11a
11F
11S
11b
11E
11M
1a
Figure 1: Heart parenchyma showing arrangement of cardiac muscles a) Bulbus arteriosus,
composed of a thick wall of fibrous connective tissue (F) and smooth muscle (S); place where the
ventricle leads into the bulbus arteriosus (arrow). b) Heart parenchyma showing arrangement of
cardiac muscles and blood cells scattered between the fibers (arrow); Edocardium (E);
Myocardium (M). a) Bar=50 µm; b) Bar=50 µm.
b) Bar=50 µm.
1121
Blood cells:
11b
a
11R
11
11E
c
111
Figure 2: Blood cells from a blood smear (Dip quick). a,c) Red blood cells (R),
Neutrophil (arrow). Bar=20µm. b) red blood cells (R), Immature erythrocyte (E);
Bar= 10µm.
1122
Spleen:
a
b
11W
R
R
W
B
Figure 3: a) spleen with red (R) and white pulp (W) -containing lymphoid cells, typically
surrounding blood vessels (B); darkly stained pigment-containing cells called
melanomacrophages centers (arrow). a) Bar=200µm. b) Bar=100 µm.
Digestive system:
Stomach:
233333*
233333*
M
S
1123
Figure 4: Stomach featuring folds (arrows), submucosa (S), epithelium (two headed
arrow), muscularis mucosa (M), gastric glands (*); Bar=50 µm.
Intestine:
11a
M
S
*
11b
*
V
11d
11c
V
V
11M
V
S
MM
M
S
11SM
Figure 5: a) Small intestine featuring intestinal villi (arrows), thin tunica muscularis (M),
sarosa (S). b) Villi (V) and microvilli (arrows) lined by columnar epithelium-enterocytes (*) and
goblet Cells (arrow heads); c) Large intestine featuring shorter intestinal villi (arrows) and
thicker tunica muscularis (M), serosa (S); d) villi of the large intestine (V), tunica muscularis
(M), submucosa (SM), muscularis mucosa (MM) Goblet cell (arrow); Bar= 200 µm.
1124
Liver:
a
b
H
*
11H
*
*
c
d
11H
c
11E
11V
11L
11M
11L
E
11V
p
11P
Figure 6: a,b) Liver tissue composed of hepatocyts (H), central vein (arrow), bile ducts (*).
c) three bile ducts (two small and one large) lined with columnar epithelium (E), connective
coat containing smooth muscle cells (M). Exocrine pancreas cells (P). The hepatocyes (H)
have high glycogen content (vacculated).d) Hepatic lobes can be seen (L), with a blood vein in
between lobes (V). a,b,c) Bar=200 µm. d) Bar=50 µm.
1125
3Pancreas:
11b
11a
11P
V
11P
11E
11H
Figure 7: Exocrinic Pancriatic cells (P)and Endocrinic pancriatic cells (E) surrawnded by
hepat cells (H); branch of portal vein (V). a ) Bar=100. b) Bar=50 µm.
33333333
Endocrine system and excretory system:
Kidney:
a
b
11H
11H
H
1126
c
Figure 8: a) Head kidney showing a few renal tubules (long arrows) and extensive area of
hematopoetic tissue (H), as in the spleen and liver the hematopoetic tissue of the kidney often
has some melanomacrophage centers (dark black areas). b) Trunk kidney showing renal
tubules (long arrows) surrounded by hematopoatic tissue (H). c) Trunk kidney shoeing renal
tubules (long short arrows), melanomacrophage centers (dark black patches) and glomeruli
(arrows); a) Bar=20 µm. b) Bar=200 µm. c) Bar=10 µm.3
Respiratory system:
Gills:
11a
P
P
11G
F
1127
Figure 9: Gills, showing: gill arch (G), gill filaments (F);Primery lamella (P) with arrey of
secondary lamellae (Long arroe), gill lamellae contain erythrocyts where gas
exchange with the water occures, (short arrows); a) Bar= 5 µm. b) Bar= 200 µm.
33
Nervous system:
Brain:
11b
11a
11OpL
11Cer
11M
11Cer
11OpL
11M
11c
11Cr
Figure 10: (a,b) Brain Metencephalon : cerebellum (Cer); Optic lob (OpL); Medula
oblongata (M); c) cerebrum hemispere (Cr), meninx prinitiva (arrow) covers the brain and
spinal cord. a) Bar=50 µm. b) Bar=200 µm. c) Bar=200 µm.
1138
Spinal Cord:
b
a
11G
G
W
W
Figure 11: spinal cord showing: Grey matter (G); White matter (W); Axons of Mauthner
neurons (arrows); meninx prinitiva (arrow head). a) Bar= 20 1m; b) Bar=200 1m.
1139
Sense Organs:
Eye:
11b
11a
AC
I
R
AC
O
C
c
11V
11CH
1
2
3
Figure 12: (a,b,c)Eye showing: cornea (C); aqueous cavity (AC); iris (I); retina (R), Optic
disc where the optic nerve leaves the retina ("blind spot") (circle) and optic nerve (O);
a)Bar=200µm. b) Bar= 50 µm c) Different layers of the Retina 1-photoreceptor layer, 2plexiform layer, 3- nerve fiber layer, choroid (CH) and vitreous layer (V); Bar=200µm.
113A
Integument:
Skin:
a
11b
11ED
11D
11D
11S
11ED
Figure 20: skin showing: Dermis (D); Epidermis(ED), Scale (S); Chromatophores
(melanocytes) (arrow); a) Bar=100 µm. b) Bar=200 µm.
1131
1
11
11
11
11
11
11
11
11
11
11Histopathology
3
1
12
1
1
Infectious diseases
Parasitic Diseases
Tetrahymena- Phylum Ciliophora; family- Tetrahymenidae.
Tetrahymena is free living ciliated protozoa, but some species can be highly lethal
fish pathogens. It is pyriform in shape with evenly distributed cilia on the cell surface.
Tetrhymena reproduction is typically by binary fission.
This pathogen can damage skin and invade internal organs. The most susceptible
fish species is guppy; therefore the disease is called "guppy killer disease". This
parasite affects a wide range of fish species, including ornamental and food fish, but
except for platy (Xyphophorus maculates) susceptibility level to Tetrahymena
infection is lower in all other tested fish species (unpublished).
Clinical signs: White patches on skin up to deep ulcerative dermatitis. Affected fish
may be lethargic.
Figure 1: wet mount of Tetrahymena spp collected
from skin of bristle-nosed catfish, Ancystrus. Long
cilia covering the pyriform shape of the protozoan
body, cilia are evenly distributed. Size ranges
11between 17-60µm x 25-100µm. Bar=0.02mm.
3
1
11
a
1
11a
11b
11c
11d
Figure 2: Molly (Poecilia sphenops), infected with Tetrahymena by IP injection.
Teyrahymena is evident a) in the gills (arrow). Bar=0.05mm; b) kidney (arrow), associated
with tissue destruction and replacement by the parasite.. Bar 0.05mm; c) Invasion of
Tetrahymena in to the liver (arrow) the parasite is seen mainly around blood vessels with
local tissue destruction; Bar=0.1mm. d) Tetrahymena inside gill blood vessel (arrow),
apparently blocking the blood flow causing focal hyperemia and congestion of the vessel;
Bar=0.05mm. There is no evidence of inflammatory response to Tetrahymena.
3
1
14
1
a
b
112
11*
11*
112 112
c
Figure 3: Goldfish (Carassius auratus auratus), infected with Tetrahymena by IP injection. a)
Tetrahymena in intestinal sub-mucosa (short arrow) and around the intestine serosa (*). A mild to
moderate inflammatory response is evident (long arrow). Bar=10 µm; b) Invasion of Tetrahymena in to
skeletal muscles and skin (short arrows). A mild to moderate inflammatory reaction is associated with the
infection (long arrow) as well as muscle tissue destruction (*) .Bar=20 µm; c) Tetrahymena surrounding
and penetrating the ovarian tissue (arrows), an inflammatory reaction is associated. Bar=50 µm.
3
1
15
1
b
11a
b
11T
T
11T
c
c
T
11T
T
Figure 4: Koi (Cyprinus carpio carpio ), infected with Tetrahymena by IP injection. a) Invasion of
Tetrahymena into skeletal muscles (black arrow). There is a high inflammatory reaction surrounding
the invasion area (white arrows). b) Liver tissue surrounded by Tetrahymena (arrows) some tissue
brake-down can be seen (T). c) Hart tissue surrounded by Tetrahymena (T), with some pericardial
brake-down (arrows), some inflammatory reaction can be seen (white arrow). Bar=50 µm.
3
1
16
1
11a
c
11b
d
Figure 5: Angel fish (Pterophyllum scalare), infected with Tetrahymena by IP injection. a) Invasion
of Tetrahymena into the liver, localized tissue detachment of hepatocytes and a void formation is
evident (arrows). b) Tetrahymena (arrow) in the intestinal sub-mucosa; Bar=20µm. c) a single
Tetrahymena inside the swim bladder (arrow). d) Invasion of Tetrahymena into pancreatic tissue
(arrows). a, c, d, Bar= 0.05 mm. There is no evident inflammatory response to the parasite.
3
1
17
1
a
a
b
E
c
d
1
Figure 6: Guppy ( Poecilia reticulate) infected with Tetrahymena by IP injection. a)
Tetrahymena in gill lamella (arrow), parasite is feeding on erythrocytes; b) Tetrahymena
(arrows) around the eye (E); c) Invasion of Tetrahymena in the skin and skeletal muscle
(arrows) with local destruction of tissue; d) Invasion of Tetrahymena into a developing
embryo with (arrows); a-d) Bar=50 µm. There is no evident inflammatory response to the
parasite.
3
1
48
1
1
White spot diseases (Ichthyophthirius multifiliis)
White spot diseases is caused by the protozoan parasite Ichthyophthirius multifiliis
(Ich). It is one of the most common diseases of fresh water fish. All fresh water fish
are susceptible to infection; in some fish species like catfish it can cause 100%
mortality. It is also called "White spot disease". The Ich trophozoite (feeding stage)
feeds on gill and skin epithelium, after it feeds it breaks through the epithelium, falls
off the fish and forms an encapsulated dividing stage (tomont). The common
temperature for Ich infection is 15ºC - 25ºC. The parasite's life cycle is 3-6 days at
25ºC, 10 days at 15ºC. Ich cysts appear as small white nodules that protrude slightly
from the surface. The epithelial erosion and ulceration result mainly from the
parasite's exit from the host, which is probably as damaging as its feeding activity
while it is on the host. There may be a secondary microbial infection due to the
lesions produced by the parasite.
11b
11a
E
11B
11O
11G
E
3
1
49
1
1
11d
c
11L
11C
11N
Figure 7: Guppy (Poecilia reticulate) infected with Ichthyophthitius multifiliis. a,b) Histological
section of the head, ciliate (arrows) are found on skin near the eye (E), operculum (O),gills (G) and
the buccal cavity (B); Bar=0.1mm. c) Histological section through a trophont, showing the
parasite's C-shaped macronucleus (N), cytoplasm (C) and cilia (arrows) covering the holotrich
parasite; Bar= 20 µm. d) I. multifiliis (arrows) on the gills Bar=100 µm.
3
1
4A
1
1
Hexmita and spironucleus
Hexamita and Spironucleus have been associated with gastrointestinal infections in
fish. Predisposing stress appears to play an important role in the severity of this
disease. Hexamita, Spironucleus and similar flagellates often reside in
gastrointestinal tract of clinically normal fish (Brugerolle, 1980; Noble & Noble, 1966;
Lom & Dykova, 1992).
Infected fish may have abdominal distention caused by fluid accumulation in the gut,
fish may be emaciated and floating feces are characteristic. Low infection may have
no evident clinical signs. Histologically; gastrointestinal lesions may range from no
evident damage to severe enteritis.
a
EE
1
C
C
b1
b2
C
Figure 8: a, b1,b2) Hexamita / Spironucleus (arrows), in the intestine of angelfish, Pterophyllum
scalare. Parasite's size ranged between 5 to 11 µm, intestinal epithelium (E), gastro-intestinal
content (C); b1) Bar=20 µm.
b2) Bar=10 µm. 1
1
3
4B
1
1
Nematoda
There are about 650 species of nematodes that parasitize fish as adults and many
others that use fish as intermediate hosts. Nematodes are round worms, free living
and parasitic. They are parasites of marine and fresh water fish. Infected fish can
appear emaciated, lethargic and may show gradual weight loss. Nematodes are
elongated, unsegmented worms, ranging in size from minute to many cm, in length.
It has a fluid-filled body, no peritoneal lining and an outer cuticle.
1
23
21
25
116
114
26
117
117
Figure 9: a) Adult parasite (P) inside the intestine lumen of angelfish1(Pterophyllum
scalare). this parasite, suspected to be a nematode, as it was diagnosed by wet mount;
Bar=50µm. b) Nematode invading intestinal mucosa. Bar: 50µm. c) Rodlet cells (R) in
Angel fish intestinal mucosa which was invaded by nematods. These cells are found in
many species of fresh water fish. Rodlet cells are secretory cells, developed from cells
near the epithelial basement membranes and migrate "upward" to secrete their contents.
These cells origin is unknown and may be seen in many pathological and normal cases;
Bar=20µm.
3
1
42
1
2
Bacterial infection
Granulomas in clown fish
Granuloma is a chronic inflammation, with development of a proliferative lesions
progressing to fibrosis. Granulomas can be coursed by foreign bodies, bacteria, parasites
and certain fungi. After a short-lived acute inflammatory response, the chronic lesion
develops as a central necrotic zone containing cell material and the initiating agent, with
a surrounding layer of macrophages and other inflammatory cells. As the lesion matures,
the macrophages form layer around the irritant, resembling epithelium (also termed
epitheloid cells). Fibroblasts surround the epitheloid cells and actively lay down collagen
11b
11a
11E
1
N
c
Figure 10: Granulomas in Clown fish12Amphiprion1ocellaris) from an intensive aquaculture system.
a) A mass from the forehead of a clown fish with multifocal graulomas (arrows). Granulomatous
tissue does not penetrate into the orbit area; E, eye; Bar=500µm. b) Granuloma in liver tissue of a
Clown fish. The center of the granuloma appears necrotic (N). Macrophages are adjacent to the
granulomatous tissue (arrows); Bar= 100 µm. c) Acid Fast staining demonstrated positively stained
bacteria (arrows) inside the granuloma, which suggest Mycobacterium as the causative agent. PAS
41
and Grocott stains were negative, suggesting no presence of a fungal agent; Bar=10µm.
3
1
1
1
11Viral diseases
11Lymphocystis
A chronic (usually many weeks), self-limiting disease affecting cultured marine and
freshwater fish. Lymphocystis is a disease of higher teleosts, it is a common viral infection
caused by Iridovirus. Lymphocystis causes low mortality and disfiguration of fish which can
render them unsalable. The transmission probably occurs by rupture or sloughing of the
lesion. Many fish carry a latent infection, which may appear after shipping or other stress.
The virus infects the dermal fibroblasts, producing hypertrophic cells that are often visible to
the naked eye. Lesions are less common in internal organs or gills.
b
a
C
F
N
E
M
11E
c
11F
11F
11I
11S
Figure 11: clown fish (Amphiprion1ocellaris from an intensive aquaculture system with
lymphocystis lesions on the mouth and back. Masses are nodular and granular in
appearance. a) mass (arrow) originating from dermis layer of the mouth area (M); Bar=500
µm. b) lymphocystis lesion showing massively enlarged dermal fibroblasts (F) or
lymphocysts, some fibroblast have a capsule (C) surrounding them and an enlarged
displaced nucleus (N), epithelium (E); Bar=100µm. c) Close-up of a lymphocystis lesion that
show diagnostic features, infected fibroblasts (F) with irregular inclusions (I), epithelium (E) ,
scale (S); Bar=50 µm.
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1
11
Non infectious disease
Muscle dystrophy
Any degenerative muscular disorder, due to faulty of nutrition of the muscles.
Causes weakness of muscles and can cause atrophy. Muscular dystrophy is
caused by nutrition deficiency of selenium and/or vitamin E.
b
11a
S
11M
Figure 1: Guppy (Poecilia reticulate), showing high mortality and following change in the food
source a few weeks earlier. Histological analysis revealed chronic muscle (M) dystrophy A) high
cellularity (arrows) around the damaged muscle, suggesting inflammatory response; Bar= 50
µm; B) Muscle fibers dystrophy (long arrow), with an inflammatory response (short arrows) in
the area of muscle distraction; Bar 20µm
11
1
3
1
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1
1
11a
113
11
Figure 2: Guppies (Poecilia reticulate), showing high mortality and weakness. a,b) Histological
11 analysis revealed chronic muscle dystrophy (arrow). High cellularity is evident, suggesting an
inflammatory response. Macrophages are evident around the damaged muscle (short arrow),
appear to be phagocytosing the damaged muscle tissue; Bar=20µm.
1
3
1
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1
11
11Spondylopathy
Any disease of the vertebrae, associated with compression of the peripheral nerve root and
spinal cord. Spondylosis is a general term for degenerative changes in the spine.
1 11a
a
b
SC
S
11C
11C
C
11G
11W
11C
Figure 3: clown fish (Amphiprion1ocellaris), from an intensive aquaculture farm were presented
with a back deformity (spondylopathy). a,b) Enlarged spinal cartilage (C) and deformed spinal
vertebra (arrows). The spinal cord (SC) is compressed; the white (W) and gray matter (G) are
clearly seen. Fish did not exhibit any evident motorical or sensory problems; a) Bar=500 µm. b)
Bar= 100µm.
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1
2
11Liposarcoma and Lipoma
Lipomas: benign fatty tumors which are occasionally encountered and may cause
dermal ulceration. Lipomas may be single or multiple subcutaneous growths of
variable sizes and shapes.1Lipomas may contain fibrous connective tissue, necrosis,
or inflammation.1Histologically, lipomas may appear similar to lobules of normal
adipose tissue, lobules of well differentiated lipocytes that have delicate cellular
membranes; small, peripheral, indistinct nuclei and nonstaining cytoplasm.
Liposarcoma: Malignant fatty tumors,1originating from adipocytes (fat cells).1
Liposarcomas are soft tissue neoplasm because of their mesenchymal or
connective tissue cell origin. Liposarcomas may be aggressive, locally invasive, and
commonly metastasize to other organs. Histologically the majority of cells resemble
mature adipocytes with a single clear fat vacuole and a peripherally located nucleus.1
Other cells in the histological section often exhibit anisokaryosis (a significant
variation in nuclear size among cells of the same general type) and anisocytosis
(considerable variation in the size of cells that are normally uniform). The cytoplasm
is abundant and contains variably-sized, lipid filled vacuoles.
11a
B
I
S
Figure 4: Clown fish (Amphiprion1ocellaris) from the Arava region where presented to the
lab with an enlarged abdomen. a) On laparotomy a large white shinny mass (arrow)
appeared to fill up the entire abdominal cavity. b) The dissected mass, appearing to engulf
and invade the internal abdominal organs; Intestine (I) and spleen (S) can be seen
imbedded in the whit fatty mass.
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1
11C
111
113
11C
11A
11B
11C
11C
d
c
28
E
119
11f
11K
11K
3
1
59
1
h
D
j
i
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11
k
11
11
11
11
11P
11
11
11
11
11
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5A
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1
Figure 5: liposarcoma in Clowen fish, Amphiprion1ocellaris:
a) Histological section showing the intensity of the invasivness of the liposarcoma (arrows)
penetratig the kidny (K), serounding the spinal cord (S) invading the muscle (M) and other
tissues; Bar=500µm.
b) Invasion of melignant lipocyts into muscle fibers (M). lipocytes appear mature with
retained thick fibrous septa (arrow); Bar=100 µm.
c) A white mass was present on a fish forhead, disected and processed for histology.
Histological section showed liposarcoma (arrow) penetrating to the eye (E) orbit (MO-10-11)
Bar=100 µm.
d) Invasion of atypical lipocytes (arrow) in to intestinal mucosa (I), there is a massive
prolifiration of the lipocytes all arround the abdominal cavity (arrow); Bar=100µm.
e) Malignant lipocyts replacing normal kidny tissue (arrows); Bar=100 µm.
f) Invasion and distruction of kidny tissue (K) by malignant lipocytes. Lipoblasts are evident,
characterised by multiple fat vacuole, which compress the nucleus (short arrow); Bar=100
µm.
g) Spleen invaded by liposarcoma cells, associated with Malenomacrophage centers
(arrows); Bar=100µm.
Histological section of the liposarcoma in the abdominal cavity:
h) Histological section of a liposarcoma. Malignant lipocytes exhibit anisokaryosis, and
contain variably sized lipid-filled vacuoles. Cells of variable morphology can be seen with
hyperchromatic lipocyte nucleus; Bar= 50 µm.
i) Monovacuolated (long arrows) and multivacuolated (short arrows) lipoblasts with a
hyperchromatic enlarged lipocyte nucleus which is compress by the vacuole; Bar=20 µm.
j) In the liposarcoma mass some mitotic figures can be seen (arrows); Bar=10µm.
k) Mature lipocytes with a single clear fat vacuole and an enlarged peripherally located
nucleus (long arrows). Immature lipoblasts (short arrows) with a central nucleus. Lipoblasts
are one of the key featurs of liposarcoma. The liposarcoma invaded pancriatic tissu, some
exocrine pancriatic cells can be seen within the mass (P); Bar=50 µm.
3
1
5B
1
References:
Berger G.B, Latimer S.K, LeRov E.B and Bain J.P, Liposarcoma in Dog and Cat;
Veterinary Clinical Pathology Clerkship Program, College of Veterinary Medicine,
The university of Georgia, Athens, GA :
http://www.vet.uga.edu/VPP/clerk/berger/index.php
Choi Y.Y, Kim J.Y and Jin Y.S; Primary liposarcoma of the ascendung colon: a rare
case of mixed type presenting as hemoperitoneum combined with other type of
retroperitoneal liposarcoma; BMC Cancer 2010, 10:239
Craig D.W, Fanburg-smuth C.J, Henry R.L , Guerrero R and Barton H.J, FatContaining Lesions of the Retroperitoneum: Radiologic-pathologic Correlation;
RadioGraphic 2009, 29: 261-290
Genton Y.C and Maroni S.E, Vulval Liposarcoma (case report); Archives of
Gynecology 1987, 240:63-66
http://www.pathology.cn/BBS/forum.php?mod=viewthread&tid=15103
http://www.sciencesway.com/vb/t9961-2
Pathology Department, Tulane University,
http://tulane.edu/som/departments/pathology/training/neoplasia_image_30.cfm
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11Squamous cell carcinoma- SCC
Unusual proliferative basal epithelium with loss of basal lamina and invasion of basal cells
down in to the underlying dermis and muscle and up into overlying epidermis. In most
cases, these arose from co-existing papilomas.
11
11b
11a
B
B
11
E
1
11
B
M
11
11
11
11c
11d
M
11
11
B
M
11
11
11
11
Figure 6: Molly fish (Poecilia sphenops) with a large mass on the back behind the head. a)
There is an overlying epidermis (E) and below the neoplastic basl cells (B); Bar= 50µm.
b,c,d) Invasion of basal (B) cells (black arrow) in to the dermis and muscle (M). Migration of
malignant epidermal cells through the limiting basement membran (white arrow), cells
showing hyperchromatic nuclei (small arrows); b,c) Bar= 100 µm. d) Bar=50 µm.
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1
1
Liver apoptosis
Apoptosis is the process of programmed cell death. Biochemical events lead to
characteristic cell changes (morphology) and death. These changes include
blabbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and
chromosomal DNA fragmentation. Unlike necrosis, apoptosis produces cell
fragments called apoptotic bodies that phagocytic cells are able to engulf and
quickly remove before the contents of the cell can spill out onto surrounding cells
and cause damage (from Wikipedia).
Processes include coagulative necrosis and shrinkage. It affects individual cells
surrounded by normal tissue. Cells undergoing apoptosis develop a very dark and
condensed chromatin and shrinkage of the overall volume of the cell.
a
b
1
Figure 7: a,b) Hepatic tissue of Clown fish 2Amphiprion1ocellaris) from an intensive
aquaculture farm, with apoptotic hepatocytes (arrows). Apoptotic cells showing
eosinophilic cytoplasm and a peripheral, condensed, darkly basophilic nucleus; a,b)
Bar= 10µm.
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