Breast Anatomy & Histology Flashcards
Where does the breast tissue lie?
Anterior to the deep fascia and pectoralis muscle
Subcutaneous tissue
Describe the structure of the breast
Lobulated lobes which drain through a duct system to the lactiferous duct and then nipple
What non-secretory tissue is found in the breast?
Adipose, fibrocollagenous tissue, suspensory pigments
Name the structure that allow movement of the breast
Retromammary space
Name the basic secretory unit of the breast
Terminal Duct Lobular Unit
Describe the structure of the duct system
Lactiferous duct drains into lobule via interlobular collecting duct which ends in terminal ductules
What is another name for terminal ductules?
Acini
What is the name of the tissue surrounding the duct system?
Interlobular stroma
What is the lactiferous sinus?
Expansion of lactiferous duct just before the nipple
Name the components of the lobule
Extralobular and interlobular ducts
Rudimentary secretory acini
Dense fibrocollagenous connective tissue surrounding the lobule
Looser connective tissue surrounding the acini
Adipose between lobules
What type of cells line the acini?
Cuboidal and columnar
What is the secretory epithelium surrounded by?
Myoepithelial - epithelial with contractile properties
What type of cell lines the lactiferous duct?
Stratified squamous epithelium
Where does the breast originate?
Modified sweat gland - apocrine
Describe the histology of the nipple
Wrinkled surface covered by a thin, highly pigmented keratinised stratified squamous epithelium - core of dense irregular connective tissue mixed with bundles of smooth muscle
As the lactiferous ducts get deeper what type of cell line them?
Stratified cuboidal epithelium
Name the type of gland found in the breast
Sebaceous gland
What happens to the breast during the menstrual cycle?
Luteal phase - epithelial cell height increases, the duct lumina enlarges and small secretions appear in the ducts
Describe the breast changes in the first trimester
Elongation and branching of smaller ducts combined with proliferation of epithelial cells, glands and my-epithelial cells
Describe the breast changes in the second trimester
Glandular tissue continues to develop with differentiation of secretory alveoli - plasma cells and lymphocytes infiltrate connective tissue
Describe the breast changes in third trimester
Maturation of secretory alveoli and development of rER
Which tissues reduce in pregnancy?
Adipose and connective tissue
State the components of human milk
Water Protein - casein and lactalbumin Carbohydrate - lactose Lipid Small amounts of vitamins and IgA
Name the two methods by which milk is secreted
Apocrine secretion Merocrine secretion (exocytosis)
Describe apocrine secretion
Lipid droplets are secreted by a surrounding membrane and small amount of cytoplasm within it
Describe merocrine secretion
Proteins in milk are made in the rER, packaged in the golgi and secreted via vesicles which merge with the apical membrane to release their contents into the ducts
What happens to the breast during menopause?
The secretory cells of the TDLUs degenerate leaving only ducts and connective tissue. There are fewer fibroblasts, reduced collagen and elastic fibres
What is the arterial supply to the breasts?
Lateral mammary branches - from lateral thoracic which originates from axillary/subclavian
Medial mammary branches from internal thoracic
What is the venous drainage of the breasts?
Medial mammary veins - internal thoracic vein
Lateral mammary veins - lateral thoracic vein
Describe the lymphatic drainage of the breasts
Subareolar lymphatic plexus
- axillary nodes
- parasternal nodes
- abdominal nodes
