Aquaporin 9’s Cellular Distribution in the Testis and Epididymis of Camels (Camelus dromedarius) during and after Rutting Season

Numerous cell types of the male genital system involved in fluid transport have tiny intrinsic membrane proteins called aquaporins (AQPs). These proteins are necessary to create the ideal luminal environment for sperm formation, maturation, and preservation. Aquaporin 9 (AQP9) allows water to move quickly across the epithelium. The current work used immunohistochemistry to clarify the expression of AQP9 in the testis (cranial and caudal parts and rete testis) and epididymis (caput, corpus, and cauda parts) of dromedary camels in the rutting and non-rutting seasons throughout the year. The results demonstrate that testicular gonocytes, Leydig cells, and rete testis and also the epididymal epithelial cells often exhibit a moderate immunoreaction to AQP9 antibodies during the mid-rutting season. However, these cells also show much higher expression levels at the beginning and end of this season. Throughout the non-rutting season, these organs exhibit intense immunoreactive staining of the AQP9 protein. In conclusion, transmembrane water and neutral solute transport via AQP9 is an essential physiological route in the testis and epididymis of the dromedary camels for spermiogenesis.