Aquaporin 9 (AQP9) Localization in the Adult Dog Testis Excurrent Ducts by Immunohistochemistry

Abstract

Aquaporins (AQPs) are small, intrinsic membrane proteins that are present in many cell types involved in fluid transport. AQP9 is a major apical water channel that is expressed throughout the efferent ducts, epididymis, and vas deferens, as well as in other regions of the human and rodent male reproductive tract. The target of this study was to examine the expression of AQP9 in epithelial cells in the adult dog efferent ducts, epididymis, and vas deferens. Samples of dog male reproductive tract comprising fragments of the testis; initial segment, caput, corpus, and cauda of the epididymis; and vas deferens were obtained from eight adult mongrel dogs. Immunohistochemistry and Western blotting procedures were used to show AQP9 localization and distribution. AQP9 expression was not detected either in dog seminiferous tubules or rete testis. However, apical labeling for AQP9 was detected in the different regions of epididymis and vas deferens, with the reaction being less intense in the caput epididymis. Thus, AQP9 is abundantly expressed in dog male reproductive tract, in which it is an important apical pathway for transmembrane flow of water and neutral solutes. Anat Rec, 290:1519Rec, 290: -1525Rec, 290: , 2007Rec, 290: . 2007 Wiley-Liss, Inc.

Microarray profiling of microRNAs expressed in testis tissues of developing primates

“…AQP9 is strongly expressed in the plasma membranes of Leydig cells in rat testis and adult dog testis. Studies showed that AQP9 may be involved in the early stages of spermatogenesis and in the secretion of tubule liquid [32,33]. RNF6 (ring finger protein 6) is predicted by hsa-miR-181d and show increased expression during meiosis.…”

Review Structure, function, and localization of aquaporins: their possible implications on gamete cryopreservation

“…Subsequent studies have identified more than 10 different types of AQPs in mammals, found in several organs of different species, such as human kidney (Deen et al, 1994), rat epithelial tissue (Lindsay and Murphy, 2007), human blood vessels (Agre and Kozono, 2003), reproductive system of rodents (McConnell et al, 2002), dogs (Domeniconi et al, 2007), and pigs (Skowronski et al, 2009). The studies with AQP1 demonstrated that these proteins are small and integral membrane protein types, crossing the membrane from side to side, and containing two semipores that together form a water channel (Verkman and Mitra, 2000), assisting the transport of solutes (Thoroddsen et al, 2011).…”

“…This same protein was expressed in the endolymphatic sac in the ear in humans, suggesting an active role in the homeostasis of the endolymph (Ishibashi, 2009). AQP2 was also found in the rete testis, efferent ducts, and epididymis of dogs, although its functional role in the reproductive tract is still unknown (Domeniconi et al, 2007).…”

“…AQPs are found in the intra-and extratesticular spermatic pathways (Domeniconi et al, 2007). In the male reproductive system, several AQPs have been expressed in different locations, such as the testes (AQP0, AQP1, AQP7, AQP8, and AQP9), efferent ducts (AQP1, AQP9, and AQP10), epididymis (AQP1, AQP3, AQP9, and AQP10), vas deferens (AQP1, AQP2, and AQP9), and accessory glands (AQP1 and AQP9) of adult mammals .…”

“…In rats and mice, AQP9 was expressed in immature germ cells (Tsukaguchi et al, 1998), efferent ducts, and over the epididymis and vas deferens of dogs, showing that this protein is abundantly expressed in the testis (Domeniconi et al, 2007). In the epididymal cells, AQP9 was expressed in greater quantities in the initial and caudal segments of the epididymis (Badran and Hermo, 2002).…”