CELL DIVISION IN THE MOUSE VAGINA DURING CONTINUOUS OESTROGEN STIMULATION

Previous work showed that during continuous oestrogen stimulation cell division in the luminal epithelium of the mouse uterus showed a distinct rhythm. A peak of cell division on days 2 and 3 was followed by a fall to control levels on day 4, with a second wave of activity beginning about day 9 (Lee, 1971). The same pattern occurred with both oestrone and oestradiol, whether given by injection or in the drinking water. The present report describes the effects of similar continuous oestrogen treat-ment on the vaginal epithelium. Cell division was estimated from colchicine-arrested mitoses, and DNA synthesis by means of [3H]thymidine labelling. Ovariectomized C 57 Black mice were given either oestradiol or oestrone (100 ng/ml) in drinking water for 14 days (Lee & Williams, 1964). Groups of 5 mice were killed each day from the beginning of treatment. Colchicine (50\g=m\g)was injected s.c. 2 h before death and 30\g=m\Ci[3H]methylthymidine (sp.act. 5\m=.\0Ci/mmol; Radiochemical Centre, Amersham) were injected i.p. 1 h before death. Autoradiographs were pre¬ pared of 5/¿m transverse vaginal sections, and in each mouse the numbers of mitoses and [3H]thymidine-labelled nuclei in approximately 400 cells of the basal layer of th