Conceptus development in vivo, endometrial and conceptus protein release in vitro following blastocyst transfer to ewes induced to ovulate at 28 days post-partum [sheep]
1993
Wallace, J.M. | Aitken, R.P. | Cheyne, M.A. (Rowett Research Inst., Aberdeen, Scotland (United Kingdom))
Blastocyst transfer procedures were developed to test whether the post-partum uterus can support conceptus development during the period of rapid growth coincident with the maternal recognition of pregnancy. In Experiment 1, the efficiency of the blastocyst transfer procedure was determined using control ewes greater than 150 days post-partum. Eight of 9 recipient ewes established pregnancies and 75 percent of blastocysts survived to term. In Experiment 2, blastocysts were transferred to control or post-partum recipients that had been induced to ovulate 28 days after lambing during the breeding season. Conceptus development was assessed 96 h after blastocyst transfer on day 15 of the cycle. At this time, conceptus mass in the 7 post-partum ewes which remained pregnant was generally lower than in the 11 corresponding control ewes. Following 96 h culture in a post-partum uterus the conceptus retained its competence to synthesize and secrete ovine trophoblast protein 1 (oTP-1) in vitro. However, despite normal oTP-1 production the conceptus tissue failed to completely suppress endometrial oxytocin receptor binding. The negative correlation between p70 production and oxytocin receptor density implies a possible role for this protein in the suppression of oxytocin receptor synthesis required to prevent luteolysis in pregnant ewes.
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