Histology
What to look for
Histology review
Histology Practical = 50 pts
• Some slides set up on scopes (~10)
• Some Powerpoint pictures on the projector
Questions I will ask:
• What kind of tissue?
• General function? (e.g. absorption, protection)
• What cells, fibers, ground?
• An example of where would you find it?
Slides
• Epithelial tissues (7 types, could be ANY
of the examples provides)
• Connective tissues (11 types, ANY
example that we looked at)
• Muscles (3 types) or neruons
• Integument and accessory structures
Epithelial tissue
Cell types
“Layers” (or not)
Simple cuboidal epithelium
• Lining kidney tubule
• Large, spherical, usually central nucleus
Another example - kidney
Simple squamous
Simple squamous
• Really flat cell layer.
• Cytoplasm very thin, visible only at point of
central nucleus
Kidney
Superficial view
(squamous)
Simple columnar
Intestinal lining
Oblong nuclei which may be much
closer to one side than the other
Simple columnar
Pseudostratified
Columnar Epithelium
• Trachea
• Look like multiple layers
• ciliated
Figure 4–5b
Another example
Transitional Epithelium
• Urinary bladder
• Looks stratified, with no coherent layers
and dome shaped cells at the top
Figure 4–4c
Transitional
Stratified Squamous Epithelium
• Skin
• Many layers thick, flat cells at top
Figure 4–3b
Stratified squamous
Stratified squamous
Stratified Cuboidal Epithelium
• Sweat gland ducts
• Two layers with large spherical nuclei
Figure 4–4b
Stratified Columnar Epithelium
• Salivary gland duct
• Only top layer lining lumen looks columnar
Figure 4–5c
Connective tissue
Dense, Loose, Proper
Irregular, Fluid, Cartilage,
Regular, Bone
Connective tissues
Connective tissue proper
• Loose connective tissue
– Areolar
– Adipose
– Reticular
• Dense connective tissue
– Dense regular
– Dense irregular
– Elastic tissue
Fluid CT
–Blood
Supporting CTs
•Cartilage
–Hyaline cartilage
–Elastic cartilage
–Fibrocartilage
• Bone
Areolar tissue
• A loose CTP
Areolar
Areolar: what to look for
•
•
•
•
Fibroblasts
Collagen fibers
Elastic fibers
Mast cells and macrophages
• Found? Throughout body, under dermis,
divides skin from underlying tissues
Adipose tissue
• Another lose CTP (note nucleus)
Adipose: what to look for
• Lots of cytoplasm
• Slim nuclei pushed off the side
• Found? You know where
Reticular tissue
• The third type of loose CTP
Reticular: what to look for
• Reticular fibers (network)
• Found? Internal framework in many sort
organs (liver, spleen) supporting the
parenchyma
Dense regular
Dense regular: what to look for
•
•
•
•
Thick parallel bundles of collagen
Thick fibers
Little space in between fibers
Small fibroblast nuclei in between bundles
• Found? Tendons, ligaments, deep fascia.
Dense irregular
More dense irregular
Dense irregular: what to look for
• Mesh of collagen fibers (irregular looking)
• Interspersed fibroblasts
• Found? Dermis of skin, periosteum,
perichondrium
Elastic tissue
Elastic tissue
Elastic tissue: what to look for
• Elastic fibers (instead of collagen fibers) in
large bundles
• Smaller width fibers
• More space in between fibers
• Fibroblast nuclei (sometimes visible)
• Found? Between vertebrae, in blood
vessel walls (underneath endothelium)
Fluid CT
• Blood
Blood: what to look for
• RBCs
• White blood cells (darker): monocytes,
lymphocytes, granulocytes
• Platelets
Supportive CT
• Cartilage – gelatinous, padding
– Hyaline cartilage
– Elastic cartilage
– Fibrocartilage
Hyaline cartilage
• Glasslike because fibers not visible
More hyaline
• There are collagenous and elastic fibers
lying in the cartilage matrix but they are
invisible because their “refractive index” is
the same as that of the matrix (like cornea)
Hyaline cartilage
Hyaline
• Hyaline cartilage (lavender matrix), with
perichondrium (pink) outside it. The latter
is a dense regular collagenous CT.
Cartilage cells = chondrocytes, and they
are lying in the lacunae.
Hyaline cart.: what to look for
• Perichondrium
• Chondroblasts (make the matrix fibers and
ground)
• Chondrocytes and lacunae
• Where? Most joints, nasal septum
Elastic cartilage
Elastic cartilage
Elastic cart: what to look for
• Many elastic fibers in matrix (or sometimes
to the sides)
• Chondrocytes in lacunae, often stacked up
like a totem pole
• Found? External ear
Fibrocartilage
Fibrocartilage: what to look for
• Irregular, wispy collagen fibers
• Chondrocytes in lacuna
• Found? Intervertabral discs of spine, pads
in knee joint
Supportive CT: Bone
Bone: what to look for
•
•
•
•
•
•
Osteon (whole circular structure)
Concentric lamellae (of matrix)
Central canal (at center of lamellae)
Osteoblasts
Osteocytes in lacunae
Canaliculi
Found? Bones!
Nervous Tissue
Figure 4.10
Nervous Tissue
Figure 4.10
Nervous tissue: what to look for
• Large, pyramidal cell bodies
• Long processes extending out
• Space (it’s a smear so cells don’t usually
take up the whole area)
• Found? Nerves, CNS
3 Types of Muscle Tissue
• Skeletal muscle:
– large body muscles responsible for movement
• Cardiac muscle:
– found only in the heart
• Smooth muscle:
– found in walls of hollow, contracting organs
(blood vessels; urinary bladder; respiratory,
digestive and reproductive tracts)
Muscle Tissue: Skeletal
Figure 4.11a
Muscle Tissue: Skeletal
Figure 4.11a
Skeletal Muscle: what to look for
• Long, cylindrical cells with obvious
striations (stripes)
• Multinucleate cells with the nuclei at the
periphery (not in the center)
Muscle Tissue: Cardiac
Figure 4.11b
Cardiac Muscle
Cardiac Muscle: what to look for
• Branching, striated cells interlocking at
intercalated discs
• Uninucleate cells
Muscle Tissue: Smooth
Figure 4.11c
Muscle Tissue: Smooth
Figure 4.11c
Muscle Tissue: Smooth
• Sheets of spindle-shaped cells with no
striations
• Central nuclei
Integument
Epidermis and dermis
Epidermis
What to look for:
• Usually darkest between stratum
germinativum and stratum granulosm
(granulosm often a dark meandering line)
• Keratinized cells often lift off the section
• Melanocytes just below basal lamina
Dermis: Papillary vs. Reticular layer
What to look for:
• Papillary layer
– has ridges
– is areolar
– Just under basal lamina
• Reticular layer
– much thicker
– Dense irregular CT
Again
Merocrine sweat gland
• What to look for:
– Found in most skin
– Coiled, tubular
– Small lumens in cross
section
– Have duct that goes all
the way to the
epidermal surface and
ends in sweat pore
– Smaller than apocrine,
don’t extend as deep
into dermis
Apocrine sweat gland
Apocrine sweat gland
What to look for:
• Associated with
hair follicle
• Only in nipples,
groin, armpit
• Large lumens
• Deeper in dermis
than merocrine
Hair with
sebaceous
glands and
arrector pilli
Hair
What to look for:
• Follicles are rarely complete
• Can often see root, papilla (at base, wher
hair grows)
• Arrector pilli muscle at an angle
• Associated glands (which are?)
Sebaceous
glands
Sebaceous glands
What to look for:
• Associated with hair follicle
• Found most everywhere hair follicles are
found in skin
• Look like cauliflower (maybe?)
Sebaceous follicle
Sebaceous follicle
What to look for:
• Also look like cauliflower
• Found on face and trunk only
• NOT associated with hair follicle
• Have duct that opens onto skin surface
Random Examples
Can you figure them out?