S100 Expression in the epididymis of dromedary camel during breeding and Non-Breeding seasons: immunohistochemical and molecular studies

The current study was undertaken to investigate the relationship between the expression of S100 gene in epididymal tissue and reproductive activity in dromedaries. Tissue specimens of both efferent ductules (ED) and of the three successive epididymal segments (caput, corpus and cauda epididymis) were obtained from 5 adult, clinically healthy dromedaries for each season (breeding and non-breeding). Specimens have been subjected to immunohistochemical and molecular investigations. The immunohistochemical findings showed that the S100-immunoreactivity (S100-IR) was the highest in the ciliated cells of ED and the principal cells in caput epididymis during breeding season. This S100-IR was reduced (ED) or even absent (caput epididymis) during non-breeding season. This reactivity was entirely absent from the epithelium lining the corpus and cauda regions (breeding season) or lining the whole length of the duct (non-breeding season). During breeding season, the peritubular smooth muscle cells (SMCs) exhibited weak (ED and corpus), moderate (caput) and strong (cauda) S100-IR. This reactivity was reduced (ED, caput and corpus) or even absent (cauda) during the non-breeding season. The blood vessels within the interstitium of the ED and the different regions of the epididymal duct failed to develop S100-IR throughout the year. The immunohistochemical findings were supported by the pattern of S100 mRNA expression, which was apparently higher in ED and caput epididymis obtained from camels in sexual activity compared to their counterparts from camels in non-breeding season. In conclusion, the seasonal variation in the gene expression in respect with the characteristic immunoreactivity and the sexual activity, proposes that S100 proteins could play a substantial role in regulation of the diverse epididymal functions in male dromedaries.