[Submicroscopic changes in the mammary gland epithelium of white rats during chronic administration of high doses of estrogen].

Ultrastructural alterations of female albino rat mammary glands in normal estrous cycle as well as in lactation, postlactation involution caused by weaning of sucklings from the nursing dams, and after administration of estrogen (synestrol) in a daily dose of 0.1 mg per 100 g body weight were studied. Particular attention was given to histochemical and morphometrical analys is of the secretory and vacuolar apparatus of the epithelial cells. A significant increase in the number of secretory granules in estrus as compared to that in diestrus accompanied by the reverse relationships in primary lysosome (small coated vesicles) count was observed. Similar relationships between the above parameters were found when the mammary glands of the lactating animals and those from the dams with their sucklings weaned were compared. The abundant primary and secondary lysosomes, autophagosomes, and heterophagosomes as well as some Golgi lamellae and smooth cisternae of endoplasmic reticulum filled with acid phosphatase were often observed in the epithelial cells of the involutary mammary glands, indicating the activation of the vacuolar apparatus. In synestrol-treated animals a gradual decrease in both secretory and catabolic activities occurred after transient successive increase of these two activities. The possible role of the relationship between the secretory and catabolic activities of the epithelial cells during mammary gland tumorogenesis is considered.