Date of Graduation

1997

Document Type

Dissertation/Thesis

Abstract

Whether growth of large, ovulatory follicles differed after different modes of stimulation with FSH and whether growth was enhanced by exogenous LH were examined in prepubertal gilts. Gilts received either a single injection of 2 mg FSH at 0 h (SUPER-OV; AUSA International, Inc., Tyler, TX) or injections every 8 h (18 mg over 64 h) and either 10 {dollar}\\mu{dollar}g porcine LH (USDA-pLH-B2; Animal Hormone Program, Beltsville, MD.) with the first injection of FSH (n = 4 and 3, respectively) or no LH (n = 3 each). Number of follicles {dollar}\\geq{dollar}7 mm in diameter and ovarian weight did not differ among treatments at 72 h following the initial injection. In a second experiment, prepubertal gilts were injected with FSH (2 mg) and LH (10 {dollar}\\mu{dollar}g) to stimulate follicular development. Gilts then were injected with hCG (750 IU) after 72 h and either additional FSH (2mg n = 10) or no additional FSH (n = 9) to determine whether supplemental FSH, to simulate the preovulatory surge, increased ovulatory response. Gilts that received the second injection of FSH (with hCG) had a greater number of 3 to 6 mm follicles (87.2 {dollar}\\pm{dollar} 16.1 vs 40.6 {dollar}\\pm{dollar} 6.8; P {dollar}<{dollar}.05) than those treated with hCG alone, but fewer of those gilts ovulated (4/10 versus 9/9, respectively; {dollar}\\rm\\chi\\sp2=7.982,\\ P<.05),{dollar} and there were fewer ovulations per gilt compared to hCG alone (5 {dollar}\\pm{dollar} 1.9 versus 9.8 {dollar}\\pm{dollar} 1.2, respectively; P {dollar}<{dollar}.05). In conclusion, follicular growth after a single injection of FSH was similar to that after repeated injections, regardless of whether or not LH was given with the first injection of FSH. However, FSH reduced ovulation rate in prepubertal gilts in which follicular development had been induced with FSH and LH. Other studies utilizing histological and radio-immunological analyses indicated that neither histamine nor mast cells were not detected in follicles from PMSG/hCG-treated prepubertal gilts and mast cells were also not found in whole ovaries from PMSG/hCG-treated prepubertal gilts. Furthermore, in vitro culture of 6-8 mm follicles at 72 h following PMSG indicated that neither histamine nor pyrilamine influenced production of follicular tissue-type plasminogen activator.

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