Corpus Luteum Function following Subtotal Hysterectomy in the Prepuberal Gilt

Abstract

SUMMARY The effect of subtotal hysterectomy- on maintenance of induced corpora lutea (CL) in prepuberal gilts, 120 to 130 days of age, was studied. Ovulation was induced with 1,000 IU Pregnant Mare Serum Gonadotropin (PMSG) followed 72 hr later with 500 IU Human Chorionic Gonadotropin (HCG). Thirteen gilts (bred controls) were inseminated on Day 0 (Day following HCG=Day 0). Fifty gilts were laparotomized on Days 6 through 9, their CL marked with charcoal and the gilts subtotally hysterectomized so that the amount of cervix and uterus left intact was: group 1 (n=13), posterior half of cervix; group 2 (n=12), cervix and posterior half of the uterine body; group 3 (n=12), cervix and uterine body; group 4 (n=13), posterior half of cervix and anterior 15% of one uterine horn. At necropsy (Day 30), three bred control gilts were pregnant while the ovaries of the remaining controls had only corpora albicantia (CA) present. The percentage of CL maintained to Day 30 for groups 1 through 4 were, respectively; 85.7, 65.9, 37.1 and 31.2. Based on these results, we suggest that, unlike mature gilts in which at least 25% of one uterine horn must be present to cause luteal regression and in which the presence of only the uterine body fails to cause luteal regression, as little as 15% of one uterine horn or the uterine body left intact will cause regression in the prepuberal gilt.