SFP: breast anatomy and histology Flashcards
(32 cards)
Describe embryonal development of breast mammary glands
Downgrowth of surface ectoderm into the mesenchyme leads to development of the gland. This also allows the gland to remain connected to the surface.
What kind of gland is in the breast?
Compound tubuloacinar.
What breast features are present from embryo-birth?
Ducts and nipple.
What breast development occurs between birth and puberty?
Duct elongation and branching.
What is the mammary line?
Feature extending from axilla to groin that is an ectodermal thickening found around 4 week gestation.
When do we have mammary buds?
6 weeks.
Describe somites in relation to breast development.
Secrete FGF that activates WNT signaling to cause ectodermal thickening in the milk line.
What is a placode?
A breast bud.
What is polymastia?
Development of breast tissue anywhere along the milk line.
What is polythelia?
Nipple development anywhere along the milk line.
Supernumerary nipples are more common in…
Men; often just looks like a mole.
Describe breast development in the first trimester.
Epithelial cords grow into the mesenchyme and mammary pits form from surface epithelium (nipple doesn’t usually protrude out until later).
Describe breast development in the second trimester.
Epithelial cords develop lumens to become lactiferous ducts. Placental hormones and local induction will drive branching of the ducts. Mesenchyme will become fat, stroma, and smooth muscle of the nipple.
Each branch of ducts serves…
A lobe of the breast.
About how many lactiferous ducts are there in the breast?
9-10.
What happens regarding breast tissue with males following puberty?
Testosterone will involute the duct system.
What happens regarding breast tissue with females following puberty?
Duct elongation and branching accelerates, terminal end buds develop as a precursor for later lactation following pregnancy, connective tissue stroma will proliferate, differentiate, and remodel.
Describe duct structure in post-adolescent females.
Lactiferous ducts form primary (lobular) branches as well as intralobular secondary branches and terminal ducts with alveolar buds.
What are myoepithelial cells?
Contractile cells surrounding secretory units to help expel milk via oxytocin signaling.
During the menstrual cycle, what happens to the breast with the increase of estrogen and progesterone?
Increased mitosis, increased number of terminal ductule lobular units (secretory units), intralobular edema from vascular changes/leakiness.
During the menstrual cycle, what happens to the breast as progesterone decreases?
Apoptosis of terminal duct epithelium and proliferative cells to return to ‘normal’ baseline breast tissue.
How does composition of the breast change with lactation?
Parenchyma goes from occupying around 20% to 80% of the tissue!
Describe breast composition in post-menopausal women.
The breast is mostly stroma with very little or no parenchyma depending on age. Ducts may still be present, but no TDLU’s.
What are two big components of breast milk?
Casein and milk lipids.
