Testicular development, sexual maturation, and seasonal variation in spermatogenesis of Raccoons in Wakayama Prefecture.

This study investigated the timing of puberty and seasonal changes in spermatogenesis in raccoons (n=156) from Wakayama Prefecture. In the 0-year class, testis size, weight, and seminiferous tubule diameter increased in winter, although only a few raccoons were sexually mature. Most raccoons in the 1-year class attained sexual maturity by autumn-winter of their second year. In the ≥2-year class, testicular activity regressed during summer. Spermatogenesis scores were used to assess age-dependent spermatogenic development. Logistic regression indicated that testes with epididymides ≥19.1 mm in size and ≥9.6 g in weight corresponded to a 50% predicted probability of the presence of morphologically mature spermatozoa. These findings provide region-specific indices of male reproductive cycles in raccoons.