LM 10.1: Anatomy and Histology of Breast Flashcards
what kind of glands are the mammary glands?
apocrine sweat glands
they develop embryologically along two lines, the milk lines, extending from the axillae to the groin
supernumerary nipples and/or breast tissue may persist anywhere along these line
what are the components of a breast?
each breast consists of 15-25 independent units called breast lobes, each consisting of a compound tubulo-acinar gland
the bulk of the breast is made up of a few large lobes that connect to the surface
what is the path of milk to the nipple?
secretory lobe –> lactiferous duct –> lactiferous sinus –> nipple
on the sides of the lactiferous sinus in the areola are areolar sebaceous gland s that are not associated with hair follicles
what makes the nipple get hard?
the nipple contains bands of smooth muscle, orientated in parallel to the lactiferous ducts and circularly near the base
contraction of this muscle causes erection of the nipple
what types of cells line the breast ducts?
the breast ducts and acini are lined by two layers of cells:
- luminal layer of epithelial cells (tall columnar or cuboidal)
- basal layer of flattened myoepithelial cells
what happens to the breast tissue during pregnancy?
the terminal duct epithelium proliferates to form greatly increased numbers of secretory acini
the breast lobules enlarge greatly at the expense of the intralobular tissue and interlobar adipose tissue, although septa of interlobular tissue still remain
pregnancy progresses, the acini begin to secrete a protein-rich fluid called colostrum, the accumulation of which dilates the acinar and duct lumina
which hormones cause breast proliferation?
- estrogen
- progesterone
- prolactin
- human chorionic somatomammotropin
- thyroxine
- corticosteroids
what is colostrum?
the form of breast secretion available during the first few days after birth
it contains a laxative substance and maternal antibodies.
unlike milk, colostrum contains little lipid
what hormone controls breast secretion?
prolactin
during pregnancy, prolactin secretion progressively increases, but high levels of circulating estrogens and progesterone suppress its activity
after birth of the baby, estrogen and progesterone levels drop and milk can be secreted –> the lactating breast is composed almost entirely of acini distended with milk, the interlobular tissue now being reduced to thin septa between the lobules
which hormone is released when the nipples are suckled?
- prolactin:
nipple stimulation by suckling causes release of prolactin from the anterior pituitary
- oxytocin
oxytocin from the posterior pituitary causes contraction of the myoepithelial cells which embrace the secretory acini and ducts, thus propelling milk into the lactiferous sinuses (milk ‘let-down’)
