Seasonal histological effects on the Leydig and Sertoli cells in the testis of indigenous dogs (Canis Familiaris)

Abstract

This study was performed on twenty adult male dogs aged 2-3 years old. Samples of testis tissue were taken during the four seasons in 2016 in Iraq. Specimens were fixed in 10% formalin. Routine histological techniques were carried out for light microscopy. H&E and PAS stains were used. During active seasons (spring and autumn) the study revealed a significant increase in the number and diameter of Leydig and Sertoli cells compared to other inactive seasons (summer and winter). Cytological indications of mitotic events of Leydig cells were clearly observed, whereas, Sertoli cells never showed any mitotic divisions. The basement membrane of seminiferous tubules appears wavy with impacts of irregular gates of cellular penetrations. It was characterized by dynamic, flexible structure, and can respond easily to the cellular mechanical pressure. The new generation of Leydig cells was derived either from the differentiation of interstitial fibroblast-like cells or from the mitosis of Leydig cells themselves; whereas the new generation of Sertoli cells was provided only by the differentiation of interstitial fibroblast-like cells. The study suggested that, after stimulation, the compensatory fibroblast-like cells can penetrate the basement membrane and then differentiate to Sertoli cells, as the similarity between the two cells were very large. It was concluded firstly that the proliferation of Sertoli cells within the seminiferous tubules was done only by the penetration and differentiation of the interstitial fibroblast-like cells and not by mitosis of Sertoli cells themselves.