Histology-Study of tissue
types
Chap 4
Main tissue types
•
•
•
•
Epithelial
Connective
Nervous
Muscle tissue
Epithelial Tissue
• Coverings and boundries
• Functions:
– Protection
– Absorption
– Filtration
– Excretion
– Secretion
– Sensory reception
Epithelial Tissue Characteristics
• Cellularity- cells packed close together
• Specialized contacts- communication and
attachment between cells
– Tight Junctions
– Desmosomes
• Polarity- have a top and bottom
– Apical surface
– Basal surface
Epithelial Tissue Characteristics
• Supported by connective tissue
– Basement membrane
• Avascular but innervated- few blood
vessels, has nerve fibers
• Regenerative- can repair “easily”
Simple vs Stratified epithelium cells
Squamous
• Simple - adapted for filtration and reducing
friction (aveoli, body cavities, kidney-loop
of Henle)
• Multilayered structure of stratified adapted for surfaces exposed to wear and
tear (skin, mouth, esophagus)
Cuboidal
• Simple (almost all)- secretion or
absorption (pancreas, salivary glands
Thyroid hormones)
• Stratified (rare) – (along ducts of sweat
glands)
Columnar
• Simple- Secretion, absorption, protection
from chemical stress (small intestine,
stomach)
• Psudostratified – typically have cilia (nasal
cavity, trachea, male reproductive tract)
• Stratified (rare) – (small areas of pharynx,
epiglottis, anus, mammary gland, urethra)
Glandular Epithelia
• Contain gland cells specialized for
secretion
– Endocrine glands-hormones
• Pancreas, thyroid , thymus, pituitary
– Exocrine glands – have tubular ducts to the
surface
• Perspiration, tears, milk, mucus
Goblet Cell
Figure 4.3b
For your pictures
1.
2.
3.
4.
5.
6.
7.
Simple Squamous- (lung)
Stratified Squamous
Simple cuboidal
Simple columnar (cilliated)- (trachea)
Pseudostratified columnar
Transitional epithelial
EC- Stratified Columnar
Connective Tissue
• Found throughout the body; most abundant
and widely distributed in primary tissues
– Connective tissue proper
– Cartilage
– Bone
– Blood
Functions of Connective
Tissue
• Binding and support
• Protection
• Insulation
• Transportation
Characteristics of
Connective Tissue
• Connective tissues have:
– Mesenchyme as their common tissue of origin
– Varying degrees of vascularity
– Nonliving extracellular matrix, consisting of
ground substance and fibers
Pg 121
Connective Tissue Proper
Loose Connective tissues
– Areolar – gel-like: cushions
– Adipose – fatty: fuel reserve, insulation
– Reticular – fiborous: internal, cell support
Connective Tissue Proper
Dense Connective tissue – collagen fibers,
elastin fibers (fibroblast cells)
– Regular – attach muscle to bone, muscle to
muscle, bone to bone (Ligaments and
tendons)
– Irregular – structural strength (Dermis of skin,
submucosa of digestive tract)
Cartilage
Solid matrix of Colloagen fibers
(condrocytes- mature condroblasts)avascular
-
Hyaline – very hard and solid – connected to
bone
Elastic – more flexible (ears, epiglottis)
Fibrocarilage – in between flex – absorbs
shock (between vertebra)
Bone
-calcified matrix w/ collagen fibers –
ostoblast cells mineralize and become
ostecytes in lacunae (cavities) vascularized
Blood
red and white bc
For your pictures:
1. Embryonic- (fetal)
2. Areolar-loose
3. Adipose-loose
4. Reticular- loose (only 2 slides – silver stained)
5. Dense regular- (collagenous fibers- regular)
6. Dense irregular-(collagenous fibers- irregular)
7. Hyaline cartilage
Same slide
8. Elastic Cartilage
9. Fibrocartilage (fiberous)
10. Bone
11. Blood
Nerve Tissue
• Function: Respond to stimuli and transmit impulses.
– Generate and conduct electrical impulses
– Regulate and control body functions
• Cells are called neurons
– Composed of cell body, axon and dendrites.
– Single cell may run up to several feet long.
• Supporting cells
– Support
– Insulation
– Protection
• (We’ll discuss in detail in Chap 11)
Muscle tissue
• Myofilaments for movement
– Actin
– Myocin
• Look for striations perpendicular to fibers
• Lots of mitochondria
Muscle tissue types
• Skeletal- very striated
– Voluntary Muscle
• Cardiac – more loose structure, striated
– Inertercolated discs (connection between
branching cells)
• Smooth – barely visible striations
– Involuntary Muscle
For your slides
• Nerve tissue
– Mammal Neuron motor nerve
• Muscle tissue
– Skeletal
– Cardiac
– smooth
Quiz yourself
• http://www.yvcc.edu/academics/biology
/seveyka/Histology%20Zoomer/histolog
y_zoomer_page.asp
• http://www.keele.ac.uk/depts/ms/resour
ces/anatomy/histologyimages/homepag
e.html
• Email me and I’ll send you the links
Tissue Repair
• 1. Inflammation
– Trauma causes damaged cells , macrophages
and mast cells to release inflammatory
chemicals
– Capillaries dilate, allow WBC, clotting proteins
and antibodies into damaged area
– Clots form to isolate area (hardening forms
scab)
Tissue Repair
• 2. Organization restore blood supply
– Granulation tissue
• Capillaries
• Fibroblasts
– growth factors
– Collagen fibers
Tissue Repair
• 3. Regeneration and fibrosis
– Epithelial cells regenerate
– Collagen (fibrous tissue) contracts to pull
edges together
• Some left behind to form scar tissue
Infections
• Simple
– Pimple or sore throat
– Regeneration only, no fibrosis
– No clotting
• Severe
– Destructive
– Scar tissue formed
• Scar tissue
– Mostly collagen fibers, shrink and compact
– Replaces original tissue type- does not function as
original tissue type
– Very strong, not very flexible
Cancer
• Tumor or neoplasm – loss of apoptosis
(programmed cell death)
– Benign- polyp - localized extra growth of cells,
encapsulated
– Malignant – Metastasis – spread to other
parts of the body, often “de”-differentiate
• Oncogenes – cancer causing genes
• Carcinogenic – cancer causing “chemical”
Types of Cancer
- Adenoma  adenocarcinoma – Epithelial glands
– Papilloma  carcinoma – epithelial squamous
– Nevus (mole) melanoma – melanocytes (pigmented
skin cells)
– Sarcoma – connective and muscle
– Lymphoma – lymphatic tissue
– Leukemia – blood
– Osteoma – bone
– Condroma – cartilage
– Lipoma – adipose
– Fibroma – fibrous connective tissue
Cancer treatment
• Surgery – can be effective for benign
tumors
• Systemic treatment
– Radiation Therapy
– Chemotherapy
– Kills ALL types of rapidly growing cells
– Unpleasant side effects
• Nausea/ vomiting
• Hair loss
USE OF HISTOCHEMISTRY TO DETECT INFECTIOUS
ORGANISMS
Gram’s stain to detect
bacteria in tissue (oil
immersion x1000)
Silver stain (GMS) to
detect presence of fungal
hyphae in tissue x200
MORE EXAMPLES OF HISTOCHEMISTRY
Luxol Fast Blue for myelin
Fontana-Masson for melanocytes
Review Assignment
• Read pg 142-143 (cancer)
• Scan Chap summary
– Pg 110-112 (cells)
– pg145-146 (histology)
• DO Review Questions
– Pg 112-113 (cells)
– Pg 147 (histology)
– Be sure to discuss all Crit think /Clinical App.
Questions w/ a partner! We will go over these in
class last ½ hr