INTRATESTICULAR RETENTION OF SPERM AND PREMATURE DECLINE IN FERTILITYIN THE DOMESTIC ROOSTER, GALLUS-DOMESTICUS

In domestic roosters, which were originally seasonal breeders and that are now kept under unnatural and unchanging conditions throughout the year, fertility peaks at 32 weeks of age (96%) but it subsequently de clines rapidly to only 5% at 110 weeks despite the fact that roosters can live for about 10 years. Roosters exhibiting this low-fertility sy ndrome have reduced levels of spermatozoa in the ejaculate. Concomitan tly, however, superabundant but apparently normal spermatozoa are foun d attached to Sertoli cells and, in addition, the seminiferous epithel ium fails to show evidence of the regression or atrophy that character izes both aging non-seasonal breeders and true seasonal. breeders duri ng non-reproductive periods. This syndrome of premature low fertility appears to stem from impaired spermiation with resultant retention of spermatozoa by Sertoli cells. To examine this problem, we compared int ratesticular incorporation of H-3-thymidine between high-fertility (32 -week-old) and low-fertility (82-week-old) roosters. Radioactivity ass ociated with spermatozoa, 33 days post-injection, was almost 50% highe r in the low-fertility roosters than in the high-fertility ones. By co ntrast, both groups showed similar characteristics with respect to a) intratesticular incorporation of H-3-thymidine, b) dynamics of spermat ogenesis, c) intratesticular level of radioactivity just before the in itiation of spermiation, and d) the duration of both spermatogenesis a nd the time required for sperm to pass through the genital tract. Our results confirm that intratesticular retention of sperm occurs in roos ters with premature low-fertility syndrome and suggest new possibiliti es for the study of the complex relationship between Sertoli cells and spermatozoa and the effects of this relationship on fertility. (C) 19 95 Wiley-Liss, Inc.