Aquaporins in bovine male reproductive tract: From calves to reproductive bulls.

The role of aquaporins (AQPs) in the male reproductive system of cattle, particularly in relation to spermatogenesis, remains incompletely understood. Therefore, the aim of this study was to analyze the developmental changes in AQP8 and AQP11 expression in the bovine (Bos taurus) male reproductive tract. Tissue samples were collected from three age groups of animals: calves aged 5-6 weeks (n = 10), young bulls aged 15-25 weeks (n = 10) and reproductive bulls aged 2-6 years (n = 11). The expression of the studied AQPs was analyzed using immunohistochemistry (IHC). The identification of AQP8 and AQP11 in specific sections of the reproductive organs was verified in the oldest group of animals using PCR. The key achievements of this study include the localization of AQP8 in gonocytes, Sertoli cells, and Leydig cells. AQP8 and AQP11 were observed in the epithelium lining the rete testis, efferent ducts, successive segments of the epididymis, and vas deferens, with expression and distribution patterns changing with animal growth and development. The present results were complemented and discussed in the context of observations from our previous works. It was demonstrated that AQP expression patterns change during animal growth and development, with the frequently diffused and heterogeneous location observed in the reproductive organs of sexually immature animals, transitioning to defined and consistent patterns in mature males.