This semi-thin section (~1.0 µm thick) of a lactating mammary gland has excellent cellular definition of the milk-secreting alveolar cells. The milk is contains abundant proteins, lipids and lactulose. The large secretion granules are easily seen in the alveolar cells.
Lobes - 15 to 20 lobes separated by septae of connective tissue with adipose cells.
Lobules - enclosed by a thin layer of connective tissue.
Alveoli (#1 and #2) - grow and expand during pregnancy and lactation.
Simple Epithelium - cuboidal or columnar secretory cells that synthesis and secrete milk.
Secretion Granules - stain pink-red and are of varying number and size. They are released apocrine secretion.