Morphology and immunolocalization of aquaporins 1 and 9 in the agouti (Dasyprocta azarae) testis excurrent ducts

Abstract

This study investigated the morphology and immunoexpression of aquaporins (AQPs) 1 and 9 in the rete testis, efferent ducts, epididymis, and vas deferens in the Azara's agouti (Dasyprocta azarae). For this purpose, ten adult sexually mature animals were used in histologic and immunohistochemical analyses. The Azara's agouti rete testis was labyrinthine and lined with simple cubic epithelium. Ciliated and non-ciliated cells were observed in the epithelium of the efferent ducts. The epididymal cellular population was composed of principal, basal, apical, clear, narrow, and halo cells. The epithelium lining of vas deferens was composed of the principal and basal cells. AQPs 1 and 9 were not expressed in the rete testis. Positive reaction to AQP1 was observed at the luminal border of non-ciliated cells of the efferent ducts, and in the peritubular stroma and blood vessels in the epididymis, and vas deferens. AQP9 was immunolocalized in the epithelial cells in the efferent ducts, epididymis and vas deferens. The morphology of Azara's agouti testis excurrent ducts is similar to that reported for other rodents such as Cuniculus paca. The immunolocalization results of the AQPs suggest that the expression of AQPs is species-specific due to differences in localization and expression when compared to studies in other mammals species. The knowledge about the expression of AQPs in Azara's agouti testis excurrent ducts is essential to support future reproductive studies on this animal, since previous studies show that AQPs may be biomarkers of male fertility and infertility.

Keywords: aquaporins; efferent ducts; epididymis; morphology; rodents.

Figure 1. Agouti testis excurrent ducts. Epithelial lining (arrow) of the rete testis (rt) (A,B). Ciliated cells (cc), non-ciliated cells (nc), and spermatozoa (s) in the efferent ducts (C,D). The transition between efferent ducts (ed), initial segment (is), and caput epididymis (ca) (E). The initial segment of the agouti epididymis showing principal (p) and narrows (n) cells, vacuoles (asterisks), and projections of the apical cytoplasm (arrowhead). Masson’s Trichrome (A,B,C,F). Hematoxylin and eosin stain (D,E).

Figure 2. Initial segment (A) of the epididymis, caput epididymis (B,C), corpus epididymis (D), cauda epididymis (E,F), and vas deferens (G,H) in the agouti. Principal (p), basal (b), apical (a), narrow (n), clear (c), and halo (h) cells appear in the epithelium lining, which lies on periductal stroma (st) in the agouti epididymis. The epithelium lining (e) of the agouti vas deferens was composed of principal (p) and basal (b) cells and lies on lamina propria (lp). The muscular coat consisted of an inner longitudinal coat (ic) and another circular one (oc). Note the microvilli (arrows), spermatozoa (s), vacuoles (asterisks), and projections of the apical cytoplasm (arrowhead). Hematoxylin and eosin stain (A,B,C,D,E,F,H). Masson’s Trichrome (G).

Figure 3. Aquaporin 1 (AQP1) immunohistochemistry in the agouti testis excurrent ducts. No reactivity in the rete testis epithelium (A). AQP1 immunoreactivity is evident in the luminal border of non-ciliated cells (black arrows) and is not detected in the ciliated cells (white arrows) of the efferent ducts (B,C). AQP1 was not immunolocalized in the epithelial cells of the initial segment of the epididymis (D), caput epididymis (E), corpus epididymis (F), cauda epididymis (G), and ductus deferens (H). Inset: adult rat kidney utilized as a positive control for AQP1 immunoreaction.

Figure 4. Aquaporin 9 (AQP9) immunohistochemistry in the agouti testis excurrent ducts. No reactivity in the rete testis epithelium (A). AQP9 immunoreactivity was observed in the epithelial cells of efferent ducts (B,C), the initial segment of epididymis (D), caput epididymis (E), corpus epididymis (F), cauda epididymis (G), and vas deferens (H). Inset: adult rat kidney utilized as a positive control for AQP9 immunoreaction.