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ARS Home » Research » Publications at this Location » Publication #68545
Title: TESTICULAR COMPOSITION, NUMBER OF A SPERMATOGONIA, GERM CELL RATIOS, AND NUMBER OF SPERMATIDS IN THREE DIFFERENT BREEDS OF BOARS

Author
item OKWUN, E - MAKURDI, NIGERIA
item IGBOELI, GAIUS - NIGERIA, NSUKKA
item LUNSTRA, DONALD
item FORD, JOHNY
item JOHNSON, LARRY - TEXAS A&M UNIVERSITY, TX

Submitted to: Journal of Andrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sperm production and fertility of boars used for mating are important factors influencing reproductive efficiency in the swine industry, and differences in testis size and structure may be important factors contributing to variation in sperm producing ability of boars. To better understand the genetic and biological mechanisms influencing testis function, differences in mature testicular structure were evaluated in three breeds of boars known to differ dramatically in number of spermatozoa per ejaculate. In reproductively mature boars evaluated at 5 to 7 months after achieving puberty, White crossbred (WC) boars had larger testes (498 +/- 35g) than did Meishan (M; 247 +/- 17g) and West African (WA; 133 +/- 10g) boars. While seminiferous tubules occupied a much greater percentage of the testes in WC (69 +/- 2%) and WA boars (60 +/- 1%) than in M boars (49 +/- 2%), all boars exhibited similar sperm production per gram of testis. Enumeration of germ cells throughout stages of spermatogenesis confirmed that the testis of M boars produced spermatozoa with a greater spermatogenic efficiency (150 to 180%) than did WC and WA boars. The greater efficiency of sperm production in M boars occurred because degeneration/loss of germ cells was lower in M boars. Further studies are necessary to elucidate the mechanisms by which M boars achieve this marked increase in efficiency of sperm production.

Technical Abstract: The objective was to characterize testicular structure in boars of three breeds known to differ in spermatozoan number in the ejaculate. Testes from mature Meishan (M, n=5; age 225 days), Whitecross (WC, n=5; age 346 days), and West African (WA, n=5; age 322 days) boars were fixed and evaluated stereologically for germ cells, Leydig cells, Sertoli cells, and other testicular structures. The mean paired parenchymal weight was highe (p<0.05) in the WC (498+/-35 g) than in the M (247+/-17 g) or WA (133+/-10 g). The testes of M boars had the smallest (p<0.05) volume percentage of seminiferous tubules and length of seminiferous tubules, but average nuclear diameters in Leydig cells and Sertoli cells were larger (p<0.05) in the M than in the WC or WA. The population sizes of all the intratubular components were positively correlated (p<0.05) with testicular size (weight). Despite large differences in testis size, the number of A spermatogonia/boar was similar for the M and WA. There was a trend for th number of round spermatids per type A spermatogonia to be greater for the M (31.69+/-4.80) than for the WC (17.61+/-3.91) or WA (21.22+/-3.05), and the M had less degeneration of germ cells between A spermatogonia and round spermatids. The larger population of A spermatogonia in the WC established the highest number of spermatids in that breed. The M partially overcame its low number of A spermatogonia by exhibiting less germ cell degeneration between A spermatogonia and spermatids. Thus, M boars exhibited a greater efficiency of spermatogenesis than did WC or WA boars.