Epithelial tissue and the Mammary Gland Flashcards
3 ways epithelial tissue differs from other basic tissues
- Closely adhering with little ECM
- Avascular
- High mitotic index
4 functions of epithelial tissue
Protection
Transport
Absorption
Synthesis and secretion
2 criteria to classify epithelia
How many layers of cells?
What is the shape of the cell on the apical surface?
Where do you find simple
- squamous
- cuboidal
- columnar
- blood vessels and body cavities
- collecting ducts of kidneys
- gallbladder
Where do you find stratified
- squamous non-keratinized
- squamous keratinized
- cuboidal
- columnar
- upper and lower GI (ex: epiglottis)
- thin and thick skin
- large ducts (sweat and esophageal glands)
- points of transition (epiglottis, recto-anal junction)
Pseudostratified epithelium
Single layer with nuclei at different heights
Upper respiratory tract (like auditory tube)
Transitional epithelium
Multilayered
Appearance changes with physiological state
Bladder
When empty (contracted), there are 5-7 layers, round umbrella cells
When full (distended) there are 2-3 layers, flat umbrella cells
What does the basement membrane stain best with?
Periodic acid-Schiff stain
4 groups of proteins in the basement membrane
Glycoproteins
Linker proteins
Collagens
Proteoglycans
Basement membrane vs basal lamina
BM: what you see under light microscope
BL: what you see under EM
3 functions of basement membrane
Attach epithelium to CT
Selective barrier
Controls epithelial cell differentiation in growth and tissue repair
2 types of tissues in glands
Parenchyma (epithelial tissue that forms the functional unit of glands - secretory cells and ducts)
Stroma (CT that forms the supportive unit of glands)
Fetal stage in mammary gland development
Milk line develops from axilla to groin, followed by regression except in pectoral region
15-25 cords invade stroma
Rudimentary duct system present at birth
Puberty stage in mammary gland development
Period of rapid growth
Due to establishment of ovarian cycle and increased level of estrogen and progesterone
Main ducts elongate, branch and end in terminal end buds
Gland size increases largely due to deposition of adipose tissue
Adult/resting stage in mammary gland development
Compounding development occurs with each ovarian cycle until about 35 yo
Ducts elongate and branch with 2 layers of cells
Terminal ducts form clusters called lobules
2 layers of cells in the terminal end buds
Cuboidal epithelial inner layer
Myoepithelial outer layer
Pregnancy/lactation stage in mammary gland development
Estrogen/progesterone/prolactin transform breast into mature organ with further ductal branching and alveolar morphogenesis
2 cell types
Lactation begins 48-72 hours after birth due to decrease in progesterone and increase in prolactin
Post lactational involution
Weaning stimulates alveolar apoptosis and involution back to resting state
Post menopausal involution
Cessation of ovarian cycle leads to a further drop in ovarian hormones, a greater loss of glandular tissue, and an increase in adipose tissue
Carcinoma
Cancer of the epithelium
Metaplasia
Replacement of one epithelium with another that is normal in appearance
Cells can reverse to other type with the removal of the stress
Dysplasia
Same epithelium but cells look different and epithelium is disorderly
3 cell types in respiratory epithelium
Stem cells
Goblet cells
Tall columnar ciliated cells
How do you describe the shape of ducts in glands?
Simple (no branches)
Compound (branched)
