The leukocytes comprise the vast majority of the somatic cells in the milk. Of course, this also allows other extracellular components like salts to diffuse into the lumen and milk components to diffuse out of the lumen into the extracellular fluid. More Mammary Cell Ultrastructure Synthetic Activity in Mammary Cells Cells within an alveolus appear to be synchronized in synthetic activity. In some alveoli the cells are all full of lipid droplets and secretory vesicles,while in other alveoli the cells are all devoid of those structures. Progressive distention of alveolar cells.
Cells are tall, columnar.
Release of products into the lumen. Cells become more cuboidal, lumen fills with milk. Intracellular synthesis may decrease during this time. If you incubate mammary tissue in the presence of radiolabeled amino acids, the radioactive trace moves through the cell as a pulse. Appears in the Golgi within 15-30 min.