Abstract
Summary
Mature mice, ovariectomized for 7 to 10 days, were administered 0.1 μg EB for 3 days as a pretreatment followed by graded levels of P alone for 9 days. On day 5, the right uterine horn was traumatized by a sharp needle throughout its length. On day 4 post-trauma, the right and left horns were separated and compared in weight. The placentomata reaction increased as P was increased to 1.0 mg/day, then decreased with levels of 2 to 10 mg/day. Relaxin alone as a substitute for P had no effect. During pretreatment on reduced levels of EB, relaxin showed a slight response and during the post-trauma period with P a marked response was observed. When EB was administered with P during post-trauma period, the reaction was reduced. This observation suggests that mice secrete little or no estrogen during the first half of pregnancy.
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