[Involution of rat mammae after abortion, cessation of lactation and vitamin A exposure].

Structural changes in the mammary gland cells have been studied in rats electron microscopically during pregnancy and involution process after cessation of lactation, as well as at initiation processes by means of abortion at various time of pregnancy (on the 8th, 13th, 20th days). The involutional processes are demonstrated to depend on differentiation degree of the mammary gland cells: intensity of autolytic processes is essentially higher at abortion performed at late stages and at cessation of lactation. Stages of physiological death of the cells are followed. Vitamin A effect on the processes of differentiation and involution is investigated.