Testicular Morphology and Function in Boars Differing in Concentrations of Plasma Follicle-Stimulating Hormone1

Abstract

The objective of this study was to evaluate morphological characteristics and testicular function of boars with different endogenous concentrations of FSH. Boars were selected at 6 mo of age on the basis of mean FSH concentrations in plasma collected at 4, 5, and 6 mo of age. Boars were classified within half-sibling families based on whether they had high concentrations of FSH (HiFSH, > 500 ng/ml, n = 9) or low concentrations (LoFSH, < 500 ng/ml, n = 7). At 14.5 mo, testes were collected, fixed, sectioned at 1 microm, and evaluated for morphological characteristics. Boars with LoFSH had larger (p < 0.01) testicular and epididymal weights than boars with HiFSH, greater (p < 0.01) daily sperm production per gram of testis, and greater total daily sperm production per boar. Testes of boars with LoFSH had a greater (p < 0.03) volume percentage of seminiferous tubules, a lesser percentage (p < 0.03) of Leydig cells, and a somewhat lesser (p = 0.06) percentage of vascular structures than testes of boars with HiFSH. Testes of boars with LoFSH had greater (p < 0.01) total tubule volume and tubule length than testes of boars with HiFSH. There were no differences (p > 0.70) in volume, diameter, or total number of Leydig cells or in total interstitial volume in testes (p > 0.41) of these two groups. Production of testosterone in vitro per paired testis and per million Leydig cells was not different (p > 0.65) between boars with HiFSH or LoFSH. Greater concentrations of FSH in blood plasma were negatively associated with development of seminiferous tubules and spermatogenic efficiency, whereas Leydig cell development was not different in boars of these two groups.

Interrelationships of Porcine X and Y Chromosomes with Pituitary Gonadotropins and Testicular Size1

“…Breed of origin of the Y chromosome had no effect on any of the testicular traits investigated. Based on the findings of Zanella et al [13], MS ϫ WC crossbred boars with small testicles have a disproportionate reduction in volume of seminiferous tubules compared with boars with large testicles. This population of crossbred boars with an identifiable QTL for testicular size provides unique resources to investigate mechanisms that affect Sertoli cell proliferation and ultimate testicular development.…”

“…This issue plus additive effects of MS alleles for the X chromosome QTL with the MS Y chromosome must be examined in greater detail with frequent sampling. Boars selected for differences in pubertal FSH concentrations had significant differences in plasma LH and testosterone when blood was collected at 20-min intervals for 2 h [13].…”

“…An additional sample was collected on Day 58 from controls and boars assigned to the 56-day group plus a sample on Day 114 from controls and boars assigned to the 112-day group. Plasma was frozen and subsequently evaluated for concentrations of FSH, luteinizing hormone (LH), testosterone, and estrone by RIA as described previously [13,22,23]. For RIA of FSH, antiserum AFP-C5288113 was used in conjunction with iodinated ovine FSH and porcine USDA-B1 as the reference preparation.…”

“…The greatest compensatory response to unilateral castration transpires during this period [11]. In a line of boars produced by crossing Chinese Meishan (MS) and White composite (WC) breeds, considerable variation exists for testicular weight [12][13][14]. Previously, subpopulations of these MS ϫ WC crossbred boars were selected 1 Names are necessary to report factually on available data; however, the U.S. Department of Agriculture (USDA) neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.…”

“…Previously, subpopulations of these MS ϫ WC crossbred boars were selected 1 Names are necessary to report factually on available data; however, the U.S. Department of Agriculture (USDA) neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. 4-6 mo of age for maximal differences in plasma FSH concentration and then evaluated at a year of age [13]. Boars with high plasma FSH had much smaller testicles and greatly lower sperm production than boars with low FSH concentrations.…”