Development and anatomy of the breast Flashcards
Normal Breast anatomy
A modified sweat gland –> 6-10 large ducts–>segmental ducts–> subsegmental ducts–> lobules (a cluster of ductules/acini)
Intralobular stroma is loose connective tissue while interlobular stroma is dense, fibrous and fatty
At menache
Distal ducts proliferate to form acini –> leading to breast growth
Changes with the menstrual cycle
Changes with menstrual cycle–> cells proliferate after ovulation leading to stromal oedema
Apoptosis and regression at menstruation
Changes with Pregnancy
greatly increased number of Acini–> in 3rd trimester epithelial cells contain lipid secretory vacuoles ready to secrete milk immediately after birth. colostrum accumulates in alveoli. When lactation stops there is regression and atrophy. Lobules atrophy with increased age–> increased fat in the stroma
Glandular elements of the breast
Extralobular ducts
Terminal duct lobular unit (TDLU)
Both contain outer myoepithelial layers and inner epithelial layer
Axillary tail of spence
extension of normal breast tissue towards the axilla
Effects of HRT on breast tissue
stimulates residual elements and parenchyma can become denser on mammogram
Developmental abnormalities of the breast
Polymastia–> accessory tissue due to incomplete involution of the mammary ridge. Polythelia–> accessory nipples. Amastia–> absence of breast develop. Congenital inversion of the nipple. Poland syndrome–> unilateral hypoplasia of breast, hemithorax & pectoral muscles
Terminal duct lobular unit (TDLU)
Most invasive cancers originate here
Calcifications often form within the terminal ducts
Gynaecomastia
20% of teenage boys experience a degree of breast development, usually transient
In adulthood it may be–> medication related, liver cirrosis, hyperthyroidism, testicular Ca, obseity
