Evidence for a systemic embryotoxic effect of early luteal regression in the ewe

Abstract

Evidence for a systemic embryotoxic effect of early luteal regression in the ewe. Beth A. Costine Experiments were performed to determine if a short-lived corpus luteum was embryotoxic in ewes given supplemental progesterone and the route of transfer of embryotoxic products. Mated ewes were lutectomized or sham lutectomized on day 4 after estrus. Following surgery, ewes received saline or PGF 2α through days 6 or 7. Pregnancy rate was reduced after treatment with PGF 2α (P < 0.001) compared to controls and was increased in PGF 2α-treated ewes by lutectomy (P < 0.05). Mated ewes with bilateral ovulations were unilaterally lutectomized, and each uterine horn was ligated to eliminate intercornual flow on day 4 after estrus. Treatment with PGF 2α on day 5 through 8 reduced pregnancy rates (P < 0.01), but embryonic survival did not differ in the uterine horns ipsilateral or contralateral to the regressing CL. The regressing CL is embryotoxic in progesterone-supplemented ewes, and embryotoxic luteal products have been shown to act by non-local pathways. iii ACKNOWLEDGEMENTS I would like to express my gratitude to my family for their involvement in my early animal husbandry aspirations, and for their continued encouragement and support. I would like to thank my mom for not letting my teachers at school be my only educators. Kindergarten through high school she was my private tutor and library. I would like to thank my dad for teaching me responsibility and for giving me biceps. Life would be dull without my brother who taught me how to have fun while doing anything. My "Grammie Costine" not only made my education financially possible, but also is an inspiration by being an educated woman-before it was hip. I am indebted to Dr. Greg Lewis and Dr. Meghan Wulster-Radcliffe for introducing me to research. Meghan spent a great deal of time teaching me the basics and gave me an excellent example to follow.