Breast Anatomy and Lactation

Study Notes

The breast is a compound alveolar gland with an apocrine mode of secretion, where the apical part of the cells is lost during secretion.

Covered with thin skin and has a central pink area of skin called the areola.
The areola contains Montgomery glands that secrete oil to moisten the areola and nipple.
The nipple is the site of main mammary gland duct opening.

Inter-lobar septa divide the breast into 15-20 lobes.
The dense connective tissue forms suspensory ligaments of Cooper, extending from the dermis of the skin to the fascia over the pectoralis muscle to support and maintain the shape of the breast.
Inter-lobular septa divide the lobes into lobules.
Adipose connective tissue is loose and has CT cells and macrophages.

Proliferation of the parenchyma occurs at the expense of the stroma during pregnancy and lactation.
Secretory units are rudimentary and only contain duct systems with no secretory units.
Alveoli begin to appear at 6 months and are lined with columnar or cubical cells, surrounded by myoepithelial cells.
Components of the duct system include intralobular ducts, extralobular ducts, interlobular ducts, lactiferous ducts, lactiferous sinus, and collecting ducts.

The epithelial lining is bilayered, with inner cubical to columnar cells and outer myoepithelial cells.
The CT surrounding the alveoli contains many lymphocytes and plasma cells responsible for the secretion of IgA, which confers passive immunity on the newborn.