Gestational changes in hamster adrenal cortex. II. Proliferative activity of adrenocortical cells in the course of...

Proliferative activity of adrenocortical cells was determined in the course of hamster gestation. The highest adrenal gland weight was noted at day 5 of pregnancy, followed by a gradual decrease towards the end of gestation. As revealed by stereology, total number of adrenocortical cells increased notably at days 5 and 10 of pregnancy and was followed by a prompt drop to the value observed in the control group. In vitro 3H-thymidine incorporation per pair of adrenals increased slightly at days 5 and 10 of pregnancy and decreased at day 15. The highest DNA content was found in adrenals taken at day 10 of gestation. The number of mitoses per adrenal section also increased at days 5 and 10 and reached the control value at day 15 of pregnancy. After vincristine administration, mitoses were predominantly seen in glomerulosa and outer fasciculata zones. Thus in the course of hamster pregnancy, a marked increase in proliferative activity of adrenocortical cells occurs up to day 10 of gestation and is followed by a significant drop in proliferative activity in the final days of pregnancy.