Mammary Gland Histology - Shaw Flashcards
About how many lobes make up the mammary gland?
15-25 lobes
***Each lobe is an independent gland
What is the sequence of ducts from the alveoli => outward in the mammary gland?
Intralobular ducts => Interlobular ducts => Lactiferous duct => Lactiferous sinus => Lactiferous duct => Nipple
The TDLU (Terminal Duct Lobular Unit) consists of what three things?
extralobular terminal duct
intralobular terminal duct
lobule (functional unit of the breast)
What kind of epithelium is located in the nipple?
Stratified squamous keratinized epithelium
No sweat glands or hair follicles!
What is the smooth muscle arrangement of the nipple?
Circumferential (lateral to ducts)
Longitudinal (nearer to ducts)
When does Melanin increase in the nipple?
during pregnancy
What glands are present in the Areola?
Areolar glands of Montgomery:
Intermediate in structure between sweat gland and true mammary gland
Sweat & sebaceous glands present
Produces oily secretions that keep the areola and nipple lubricated and protected
Tubercles (glands) increase in size during pregnancy
What nerve endings are in the nipples?
Tall connective tissue papillae with numerous Meissner’s corpuscles
When/Where are Alveoli present in the mammary gland?
Mature (lactating) gland:
Secretory units
Distal ends of intralobular ducts
Cuboidal to squamous epithelium
What are the two secretory processes that are utilized to produce milk?
- lipid (apocrine) => secretory granules
2. protein (merocrine/eccrine) => exocytosis of particles
What cells infiltrate the mammary gland during pregnancy?
Plasma cell infiltration => IgA from plasma cells gives passive immunity to infant
(Colostrum production: protein-rich; vitamin A; sodium; chloride; lactalbumin (“whey” protein); IgA)
What causes the milk to advance from the alveoli into the ducts?
Myoepithelial cells => Oxytocin from pituitary induces myoepithelium contraction during nursing
What is the difference between milk at the beginning of a feeding versus the endo of a feeding?
Beginning of Feeding => white (protein-rich)
End of Feeding => white/yellow (lipid-rich)
What changes in the mammary gland occur during weaning and involution?
Secretory products resorbed
Alveolar size decreases
Alveolar degeneration
Connective tissue increases
What are the postmenopausal changes in the mammary gland?
Atrophy of gland and stroma
A few ducts may persist
Cyst formation is common
Connective tissue becomes more dense
