Histo Flashcards
Step 1 of preparation of histologic sections
tissue collection
Step 2 of preparation of histologic sections
Fixation and trimming
in 10% formalin
step 3 of preparation of histologic sections
Dehydration
series of alcohols increasing to 100%
step 4 of preparation of histologic sections
Paraffin embedding
Step 5 of preparation of histologic sections
Sectioning with microtome
3-4 micrometers
step 6 of preparation of histologic sections
Straightening sections on water bath
step 7 of preparation of histologic sections
transferring sections to slide
step 8 of preparation of histologic sections
staining and coverslipping
Blue stain for mainy genetic materials (DNA and RNA)
Haematoxylin
Pink stains for mainly proteins
Eosin
Key Characteristics of the epithelium
6
- Covers all external and internal surfaces of the body
- Has polar orientation (One side faces lumen and other side is anchored to another tissue)
- Contains no blood vessels
- can have apical modifications
- minimal extracellular space between cells
- forms a basement membrane
how are epithelium described
2
- Morphology (shape and arrangement)
- Function (Glandular or non-glandular)
types of epithelia regarding structure
2
- Simple epithelium (single layers of cells)
- Stratified epithelium (Multiple layers of cells)
simple squamous characterisitcs
3
- One layer of flat and thin cells
- best suited for passive transport of substances across the cytoplasm
- provide very little protection and thus are not found on surfaces subject to high stress
alveoli, vessels, body cavities
Simple cuboidal epithelium
2
- one layer of thicker, deeper cells that look like squares
- usually associated with secretion and/or absorption
thyroid, kidney, lung, ovary, ducts and secretory portions of many gland
simple columnar epitheial
3
- one layer of tall, long and thin cells
markedly polarized - often have apical modifications (cilia, microvilli etc.)
- usually associated with secretion and/or absorption
intestine, female repro tract, many exocrine glands
Simple pseudostratified epitheial
4
- One layer, but due to the arrangement of the nuclei, appears to be multilayered
- all cells rest on the basement membrane
- secretion and movement of particles along the tubular organs
- also called respiratory epithelium
trachea, bronchi, epididymis, vas deferens
Stratified squamous epithelium
4
- multiple layers of thin, flat cells
- most common multilayered epithelia. cover most of the external and some internal bodyparts
- protect underlying tissues and prevent their desiccation
- some keratinise. In SA, only occurs on outside and not where where tissue remains moist, LA can occur in mouth, etc
stratified cuboidal epithelium
3
- multpile layers of cube like cells
- not abundant
- found covering areas of trasnition between simple and stratisifed epithelia
stratified columnar epitheial
3
- multiple layers of tall, thin cells
- not abundant
- found covering areas of transition between simple and stratisfied epithelia
transitional epithelium
5
- appearance changes from thick stratified columnar to thin stratisfied squamous
- some of the surface cells are binucleated
- often seen in urinary tract as they have to expand and contract to accomodate liquid contents of the bladder/ureters
- Only found in the urogenital system.
- subject to marked cariation of internal pressure (cell type depends on degree of distinction
AKA urothelium
how are epithelial glands classified
4
- method of secretion (endocrine vs. exocrine)
- type of secretion
- shape
- cell numbers
Endocrine glands
4
- ductless and have no connections to external or internal surfaces
- produce hormones
- near blood vessels
- high diversity in morphology
where do Exocrine glands secrete to
- secrete its product to a lumen or free surface
Types of secretory product consistency from exocrine glands
3
- serous (clear, watery fluid)
- mucous (more viscous fluid)
- mixed (mixture of above)
types of secretion of exocrine glands
3
- merocrine (exocytosis, cell membrane remains intact and fuses to expel contents)
- holocrine (cell membrane ruptures and “commits suicide”
- Apocrine (cell pinches off surface with secreted product)
Apical modifications
3
- cilia (actively motile, long cell processes)
- Microvilli (non-motile small projections specialised for abosrption. increase surface area)
- stereocilia (long microvilli)
what are the 3 types of Cell junctions
3
- adherent junctions (cells anchor together to insure tissue cohesion)
- tight junctions (control what eneters the body)
- gap junctions (for communication between cells)
Adherent junctions
linking of junctions provides stifness of tissue
- cell to cell: desmosomes
- cell to extracellular matrix: hemidesmosomes
tight junctions
3
- controll the entrance of compunds (nutrients etc.) to the blood vessels from the intestinal lumen.
- limit the paracellular movement of water and other molecules
- 2 pathways for compunds to transverse epithelial sheet: paracellular (between cells) and transcellular (across cells)
Gap junctions
1
- aqueous channels (pore like) that allow small molecules to pass between two adjacent cells
less than or equal to 1000Da in molecular weight
how are exocrine glands classified
classified regarding the number of cells (multi/unicellular)and shape, type of secretory product and type of secretion
