Anatomy and Histology of the Breast Flashcards
What kind of gland is the breast?
Subcutaneous gland
What is the secretory tissue of the breast made up of?
15-25 lobes = each consist of a compound tubulo-acinar gland
What drains the tubulo-acinar gland of the breast lobes?
Drains via a series of ducts leading to the nipple
What is adjacent to the secretory lobes of the breast?
Dense fibrous tissue = this is in turn surrounded by adipose tissue
What are the suspensory ligaments?
Larger condensations among fibrous connective tissue
Where do the suspensory ligaments extend?
From dermis to deep fascia overlying muscle of anterior chest wall
Where are the suspensory ligaments most pronounced?
In the upper breast = thought to support breast tissue
What is the basic functional secretory unit of the breast?
Terminal duct lobular unit
How is the duct system organised in the non-lactating breast?
Terminal ductules lead into an intralobular collecting duct which leads into lactiferous duct for that lobe
Where does the lactiferous duct lead?
To the nipple = passes through an expanded duct region near the nipple called the lactiferous sinus
What kind of ducts exist in the lobule of the breast?
Both intralobular and extralobular ducts
What surrounds the lobule of the breast?
Dense fibrocollagenous tissue
What are some features of the lobule?
Adipose tissue between lobules
Rudimentary secretory acini
What surrounds the acini in each lobule?
Looser connective tissue = allows rapid expansion during pregnancy
What cell type line the acini of the lobule?
Secretory epithelial cells = vary from cuboidal to columnar
What surrounds the secretory cells of the acini?
Myoepithelial cells = contractile epithelial cells which are in turn surrounded by basal lamina
What lines larger ducts?
Epithelium = varies from thin stratified squamous to stratified cuboidal
What does red staining of the duct represent?
Usually represents coagulated proteinaceous material
What is the surface of the nipple like?
Wrinkled surface and is covered by a thin highly pigmented keratinised stratified squamous epithelium
What does the core of the nipple consist of?
Dense irregular connective tissue mixed with bundles of smooth muscle
How many lobes of the breast does each lactiferous duct serve?
One duct serves each lobe
What cell types line the lactiferous duct?
Near surface = stratified epithelium
Deeper from skin = stratified cuboidal epithelium
How thick can lactiferous ducts be deeper beneath the skin?
May only be one cell thick
What glands are present in the nipple?
Sebaceous glands = end directly on the surface of the skin
What changes occur in mammary glands during the luteal phase of the menstrual cycle?
Epithelial cells increase in height
Lumina of the duct enlarges
Small amounts of secretions appear in ducts
Can changes occur in the mammary gland during the menstrual cycle even in the absence of pregnancy?
Yes
What changes occur in the mammary glands during the first trimester?
Elongation and branching of smaller ducts
Proliferation of epithelial cells of glands and myoepithelial cells
What changes occur in the mammary glands during the second trimester?
Glandular tissue continues to develop with differentiation of secretory alveoli
Plasma cells and lymphocytes infiltrate nearby connective tissue
What changes occur in the mammary glands during the third trimester?
Secretory alveoli continue to mature with development of extensive rER
What are the changes that occur in the mammary gland during pregnancy accompanied by?
A reduction in the amount of connective and adipose tissue present
What hormones stimulate proliferation of secretory cells in the mammary glands during pregnancy?
Oestrogen and progesterone
What is the composition of milk produced by the humans?
88% water 15% protein = mainly lactalbumin and casein 7% carbohydrate = mainly lactose 3.5% lipid Small amounts of ions, vitamins and IgA
Are all compositions of milk secreted by the same mechanism?
No = two methods are apocrine and merocrine (exocytosis) secretion
What occurs in apocrine secretion?
Lipid droplets are secreted surrounded by membrane and carrying a small amount of cytoplasm
What occurs in merocrine secretion?
Proteins in milk are secreted via vesicles which may merge with apical membranes to release only their contents into the duct system
What happens to the proteins in milk before they are released via merocrine secretion?
Made in the rER and packaged in the Golgi apparatus
What changes occur in the breast during menopause?
Secretory cells of terminal lobular unit degenerate leaving only ducts
What happens to the connective tissue of the breast during menopause?
There are fewer fibroblasts and reduced collagen and elastic fibres
What occurs in ductal carcinomas?
Normal breast stroma has been invaded by malignant epithelial cells = ducts may be filled and expanded by cancerous growth
