Thyroxine Administration and Reproduction in Rats

Abstract

Appropriate dosages of thyroxine increased uterine metabolism at the proestrus stage of the cycle in female rats with ovaries intact, but decreased the uterine metabolism induced by estradiol administration in spayed females. Thirty micrograms l-thyroxine administered daily for 6 days prior to breeding and discontinued at the time of breeding increased ovulation rate, implantation rate and litter size.