Identification of a Gonadotropin Releasing Hormone-Like Factor in the Rabbit Placenta (Pregnancy, Corpus Luteum, Fetus)
First objective was to determine day at which maternal recognition of pregnancy occurs in the doe. We examined the effect of embryo removal on progesterone (P(,4)) and luteinizing hormone (LH) levels in pregnant does. We found that P(,4) and LH profiles of pregnant does that had embryos removed prior to day 7 were not different from those of pseudopregnant controls. Next we determined the effect of conceptus (fetus and fetal placenta) removal at days 11, 12 and 18 on maternal serum P(,4) and LH levels. Serum P(,4) and LH profiles of does whose conceptuses were removed on d 11 were identical to pseudopregnant controls. Conceptus removal on d 12 or 18 caused a precipitous decline in P(,4) levels within 48 h. These data demonstrate that maternal recognition of pregnancy occurs by d 12 of gestation.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign