A Scanning Electron Microscopic Study of Mammary Myoepithelial Cells, with Special Reference to Their Role in the Ejection of Milk

摘要

Connective tissue components around alveoli were removed with a HCl-collagenase digestion method. Myoepithelial cells (MECs) of the mammary glands in lactating rats under mormal and experimental conditions were observed by scanning electron microscopy (SEM). MECs with elongated cell bodies and long, bifurcating processes formed a delicate network around the alveolus. The basal surface of MEC was generally flat. In rats injected with oxytocin, the mammary glands were markedly different in morphology. Most of the alveoli were rugged in basal aspect and were smaller in volume. MECs had prominent folds indicating squeezing of the alveolus occurred probably due to the contraction of MECs. Therefore, it was concluded that MECs in the mammary gland play an important contractile role in milk ejection.