Luteal function in the Hysterectomized Prepuberal Gilt1

Abstract

The effect of hysterectomy on maintenance of induced corpora lutea (CL) in prepuberal gilts, 130 to 140 days of age, was studied. Ovulation was induced with 750 IU PMSG followed 72 hr later with 500 IU HCG (Day following HCG = Day 0). Ten gilts were bilaterally hysterectomized on Day 6 to 10, while 10 gilts (controls) were artificially inseminated on Day 0 or 1 and sham operated on Day 6 to 10. Blood was collected from all gilts on Days 10, 14, 16, 20, 24 and 29 and plasma progestin concentrations determined by radioimmunoassay (RIA). On Day 30, uteri were examined for embryos and ovaries for CL. One gilt in each group failed to ovulate and was eliminated from the study. In addition, one control gilt had an abnormal number of CL (54 CL) and was eliminated. The average numbers of CL ± SE for the control and hysterectomized gilts were 6.4 ± 1.4 and 7.7 ± 1.5, respectively. The plasma progestin concentrations (ng/ml), adjusted for the number of CL, on Days 10, 14, 16, 20, 24 and 29 for the control and hysterectomized gilts were, respectively: 11.7, 9.5, 4.4, 1.3, 1.2, 1.3 and 11.3, 11.3, 8.7, 8.5, 7.1, 8.0. On Day 30, no embryos were present in the uteri and all CL had regressed in the control gilts, while the CL in all hysterectomized gilts were still present and secreting progesterone. These results demonstrate that luteotropic support is adequate to maintain functional CL when the luteolytic mechanism is removed by hysterectomy. Therefore, failure of the prepuberal gilt to maintain pregnancy may be due to an imbalance between the luteolytic and luteotropic mechanisms. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science