[Localization of calcium in the secretory cells of the mammary glands in response to oxytocin].

Distribution of Ca2+ ions, precipitated by means of pyroantimonate potassium, has been investigated electron microscopically in secretory cells of the mammary gland of lactating white mice. In the glandular cells, that are at the state of inhibition of secretory activity, the cytochemical reaction product is localized on the internal side of the basal, lateral and apical parts of the plasmolemma, in mitochondrial matrix, in cisterns and in the Golgi complex vesicles, in the nuclear areas, occupied by euchromatin. Oxytocin effect produces a certain complex of ultrastructural changes in the cell accompanied by redistribution of Ca2+ ions. Amount of precipitate in mitochondria decreases. It is revealed in the lumen of dilated canals of the granular endoplasmic reticulum, in the zone of decondensated nuclear chromatin, in the Golgi complex vesicles. The vesicles become larger and fuse with each other. The changes mentioned demonstrate increased synthetic and transport processes, occurring in the glandular epithelium of the mammary gland after oxytocin effect.