Seasonal Changes in Spermatogenesis and Immunolocalization of Inhibin/Activin Subunits in the Wild Male Ground Squirrel (Citellus dauricus Brandt)

Abstract

The objective of this study was to investigate the seasonal changes in spermatogenesis and the immunolocalization of the inhibin α and inhibin/activin (β_A and β_B) subunits during the breeding and non-breeding seasons in the wild male ground squirrel. The testicular weight and size and seminiferous tubule diameter were measured, and histological observations of testes were performed. The sections of the testes were immunostained by the avidin-biotin-peroxidase complex method (ABC) using polyclonal antisera raised against porcine inhibin α, inhibin/activin β_A and inhibin/activin β_B during the breeding and non-breeding seasons. There were marked variations in testicular weight and size and seminiferous tubule diameter between the breeding and non-breeding seasons, and all types of spermatogenic cells, including spermatozoa, were found in the breeding season. In addition, immunoreactivity was also detected for the inhibin α, β_A and β_B subunits in Sertoli and Leydig cells during the breeding season, but immunostaining was only present for the inhibin α and inhibin/activin β_B subunits in Sertoli cells during the non-breeding season. These results suggest that seasonal changes in testicular weight and size and seminiferous tubule diameter of wild ground squirrels are correlated with changes in spermatogenesis, and the cellular localization of the inhibin/activin subunits showed season related changes in the breeding and non-breeding seasons.