Abstract
Seasonal changes of the testis were studied in 30 specimens of the male raccoon dogs, Nyctereutes procyonoides, which were killed by a traffic accident in Kagawa Prefecture during 1996-2001. Ages of the animals were determined by cementum layer method. The length and the width of the testis were significantly correlated with the weight plotted in logarithm. The testis weight grew from July to October within one year old. The testis weight then became heaviest from January to April, when the epididymis contained sperms. And the testis weight decreased in May. Therefore, the male raccoon dogs attained its sexual maturity within one year old, and the maturation period was estimated from January to April. The maximum period of the testis weight accorded with the previous reports of the behavioral changes and coition observed in captivity.
