Breast Histology and Anatomy Flashcards
How would you generally describe the breast?
Subcutaneous gland
What is the secretory tissue of the breast made up of?
15-20 lobes
What does a lobe in the breast consist of?
Tubuloacinar gland which drains via series of ducts leading to nipple
What supports the breast tissue?
Suspensory ligaments which extend form dermis of skin to deep fascia overlying the muscle of anterior chest wall
Where would you find suspensory ligaments in the breast?
Amongst the fibrous tissue in breast
What does TDLU stand for?
Terminal duct lobular unit
What is a TDLU?
Basic functional secretory unit of the breast
What does TDLU lead to in the non-lactating breast?
Intralobular collecting duct which leads to lactiferous duct for that lobe
What duct leads to the nipple and what does it pass through to get there?
Lactiferous ducts lead to the nipple
-Pass through lactiferous sinus
What is lactiferous sinus?
Expanded duct region near nipple
What cells line acini within the lobule?
Secretory epithelial cells (vary from cuboidal to columnar)
What surrounds secretory cells of acinus?
Myoepithelial cells
What are myoepithelial cells?
Epithelial cells with contractile properties
-Thought to help push milk out of the ducts
Example of larger ducts in breast?
Lactiferous ducts
What are lactiferous ducts lined by?
Epithelium that varies form stratified squamous to stratified cuboidal
-Myoepithelial cells also can be present
What do many people believe mammary glands represent?
Modified sweat glands in particular apocrine glands
What is nipple covered by?
Highly pigmented keratinized stratified squamous epithelium
What is the core of the nipple made of?
Dense irregular connective tissue mixed with bundles of smooth muscle
Breast changes in luteal phase of menstrual cycle?
Epithelial cells increase in height
Lamina of ducts become enlarged
Small amounts of secretions appear in ducts
What happens to breast tissue following menopause?
- Secretory cells of TDLUs degenerate leaving only ducts
- In connective tissue there are fewer fibroblasts and reduced collagen and elastic fibres
Breast change in first trimester of pregnancy?
- Elongation and branching of the smaller ducts
- Proliferation of epithelial and myoepithelial cells of gland
Breast changes in 2nd trimester?
-Glandular tissues continue to develop with differentiation of secretory alveoli
Plasma cells and lymphocytes infiltrate connective tissue
Breast changes in 3rd pregnancy trimester?
Secretory alveoli continue to mature with development of extensive rER
What are all pregnancy breast changes accompanied by?
Reduction in the amount of connective tissue and adipose tissue present
Generally what happens to breasts in pregnancy?
Oestrogen and progesterone stimulate proliferation of secretory tissue and fibro-fatty tissue becomes sparse
What is apocrine secretion?
Lipid droplets are secreted surrounded by membrane and carrying small amount of cytoplasm with it
What is merocrine secretion?
Proteins in milk are made in rER, packaged in golgi apparatus and secreted via vesicles which merge with apical membrane to release only their contents into the duct system
Medial side of breast is supplied blood by?
Medial mammary arteries
-Branches of internal thoracic artery (branch of subclavian)
What are medial mammary arteries branches of?
Internal thoracic artery>branch of subclavian
Lateral side of the breast is supplied blood by?
Lateral mammary arteries
-Branches of lateral thoracic artery (branch of axillary artery)
What are branches of the lateral thoracic artery?
Lateral mammary arteries
What is the lateral thoracic artery a branch of?
Axillary artery
Venous drainage of breasts?
Medial and lateral mammary veins
Lymph drainage of breasts?
Most lymph drains to axillary nodes (>75%)
The rest drains to parasternal and some to abdominal nodes
