Histology: Epithelium and Glands

types of epithelia

simple

stratified

pseudostratified

types of glands

unicellular, multicellular, simple, compound, exocrine, endocrine

types of secretion

serous

mucous

mechanisms of secretion

merocrine

apocrine

holocrine

2 general classes of epithelia

lining or glandular

polarized

free apical surface, basal surface attached to basal lamina

epithelia are all

avascular

epithelial function

protection, surface transport, absorption, secretion, trans-epithelial transport, reproductive, special sensory, contraction

keratinization cell turnover timeline

3 weeks-1 month

example of apical to basal trans-epithelial transport

kidney tubules transport nutrients from the lumen to basal connective tissue

example of basal to apical trans-epithelial transport

lymph resorption into lymphatics

Epithelial type is determined by _____ and _______

number of layers (simple/stratified)

cell shape at the free surface

what’s an example of reproductive epithelial function?

seminiferous tubule generates sperm

what’s an example of special sensory epithelial function?

tast buds, hair cells in cochlea

what’s an example of contraction epithelial function?

myoepithelium

For most organs, if you know the function of the _______, you
know the function of the organ

epithelium

simple (and types)

one cell thick (squamous, cuboidal, columnar)

simple squamus epithelium

simple cuboidal epithelium

simple cuboidal epithelium

simple columnar epithelium

simple columnar epithelium

stratified columnar epithelium

stratified squamous keratinizing epithelium (SSKE)

stratified squamous non-keratinizing epithelium (SSNKE)

stratified squamous epithelium

stratified (and types)

multi-cell layered (columnar, squamous)

name determined by shape of cell layer at free surface

stratified columnar epithelium

pseudostratified

All cells contact basal lamina, not all reach free surface

____________ has dead layer on top

Keratinizing epithelium

pseudostratified epithelial

pseudostratified epithelial

transitional epithelium (unique to urinary system)

transitional

large surface cells, often binucleate (unique to urinary system aka urothelium)

wandering lymphocytes are

specialized white blood cells for immune surveillance

what is the oral cavity epithelium characterized by

mostly stratified squamous (inner cheek, hard and soft palate, lip, gingiva)

which regions of the oral cavity epithelium are partly keratinized?

lip and gingiva

basal lamina is comprised primarily of

type IV collagen

laminin

(both form “chicken wire” networks

the ______ is the most surface level of skin (dead skin) during keratinization

corneum

cornuem cells have _______ but no _______

cell membrane; nucleus/organelles

what is the “dark layer” right beneath corneum

stratum granulosum (has lots of protein)

in para-keratinization, there is no “dark layer” aka no

no stratum granulosum

in between the stratum corneum cells, there is

lipid (water proofs skin and keeps fluid in!!)

you can develop para-keratinization via

diet

keratinization occurs on surfaces that need extra

protection (hard palate for example)

surface cells in para-keratinization are

living (have nuclei)

all glands begin as

epithelial ingrowth from surface

all epithelia rest upon a

basal lamina

basal lamina function

support for epithelia

development, differentiation, morphogenesis

cell migration

filtration barrier

many non-epithelial cells have an

external lamina (these non-polarized cells have no basal surface)

what are some non-epithelial cells

adipocytes, muscle cells, Schwann cell

what cell is this and what is the arrow pointing to

Schwann cell

pointing to external lamina

what cell is this and what is the arrow pointing to

smooth muscle cell

pointing to external lamina

types of epithelial glands

unicellular

multicellular, simple (unbranched)

multicellular, compound (branched)

what are the arrows pointing to

goblet cells

all glands begin as

an epithelial ingrowth from the surface

modes of gland secretion

exocrine (merocrine, apocrine, holocrine, mixed)

endocrine

types of exocrine secretion

merocrine

apocrine

holcrine

mixed (merocrine/apocrine)

all exocrine secretion secretes into

lumen via ducts

endocrine secretion secretes into

connective tissues/capillaries (interstitial space)

exocrine glands ________ contact with surface epithelium

maintain

endocrine glands ________ contact with surface epithelium

lose

merocrine

secretion by exocytosis (only produce is released)

example of merocrine secretion

pancreas

example of endocrine glands

thyroid

what are some typical secretions from merocrine glands?

-zymogens
-sweat
-mucus
-lysozyme

what is this gland?

salivary gland

apocrine

(aka decapitation secretion)

a portion of the apical membrane & cytoplasm is released along with the product

what gland is this

mammary gland

holocrine

the entire cell and its contents (sebum) become the secretory product

what are examples of holocrine secretion

Fordyce spots

sebaceous gland

nature of secreted products (2 types)

serous

mucous

serous secretion

-watery secretion
-abundant RER
-round nucleus
-cells well stained

mucous secretion

-thick secretion
-clear cytoplasm
-flat nucleus (artifact of preparation)
-cells poorly stained

_____________ cells (derived from epithelium) help to expel the secretory products

myoepithelial