Attainment of spermatogenesis in Swedish cross-bred boars.

Twenty peripubertal Swedish cross-bred boars were used to study the testicular differentiation and the maturation of spermatozoa (epididymal) between 100 and 180 days of age. In all animals the sex cords were small and solid at 100 days of age. Spermatogenesis started at approximately 115 days of age and was completed, i.e. the cellular organization of the seminiferous tubules indicated a sexually mature testis with normal spermatogenesis, at 180 days of age. By 125 days of age only a few spermatozoa were found in the cauda epididymidis Furthermore, a high frequency of sperm morphological alterations were seen. The sperm concentration in the cauda increased with increasing age, and simultaneously the frequency of abnormal spermatozoa decreased. However, not all boars had a 'mature' semen picture in the cauda epididymis at 180 days of age.