| Abstract: | The effect of estradiol-17beta on the length of the various phases of the cell cycle was studied in the neonatal mouse uterine, and cervical epithelium. A double labelling method was used, and in addition labelled mitoses were counted. In the uterus proper, estradiol shortens the length of the total cell cycle. TC, from 17-9 hr to 15-7 hr, and the duration of S phase, Ts from 6-7 to 5-1 hr 6 hr after estradiol treatment. 12 hr after estradiol treatment, TC is shortened to 7-4 hr and Ts to 4-5 hr. The shortening of TC at 12 hr is manily due to an effect on TG1, which is shortened from 8-55 hr in untreated animals to 1-8 hr in estradiol treated animals. The TC of cervix epithelium cells in untreated animals was found to be 21-8 hr. After treating the mice for 6 hr with estradiol the tc was now increased to 47 hr and further to 61-2 hr following 12 hr treatment with the hormone. Ts increases from 8-3 hr to 15-2 hr following 6 hr estradiol treatment, and to 15-4 hr after 12 hr treatment. The effect is most pronounced in TG1, which is lengthened from 10-95 hr in untreated animals to 28-1 hr and 43 hr, respectively, in animals treated for either 6 or 12 hr with estradiol. |
