EFFECT OF CONTINUOUS OESTROGEN ADMINISTRATION ON OESTRUS, OVULATION AND FERTILIZATION IN RATS AND MICE

Abstract

SUMMARY Stilboestrol was administered in the drinking water at several different concentrations to groups of normal adult rats and mice. Continuous vaginal cornification was obtained with the higher dose levels and both species showed a capacity for repeated coitus at intervals corresponding approximately to those separating oestrous periods in untreated animals. The response was much more uniform in the mice. Inhibition of ovulation required dose levels well above those that clearly influenced the nature of the vaginal smear. The great majority of ovulated eggs were found to undergo spermatozoon penetration, and supplementary spermatozoa were commonly seen. Results suggest that the frequency of spermatozoon penetration was increased by moderate oestrogen dosage. Fertilization appeared to be quite normal.