Cystic rete testis in a central bearded dragon (Pogona vitticeps)

Abstract

The rete testis forms from the mesonephric tubules in a series of interconnected channels in which spermatozoa travel in a high volume of fluid between the seminiferous tubules and efferent ductules. Cystic rete testis can be identified by uni- or multilocular cysts with a wall lined by low cuboidal epithelial cells and a dense fibrous stroma. An 11-year-old male central bearded dragon (Pogona vitticeps) was evaluated for a coelomic mass. The animal had no other clinical signs apart from coelomic mass effect. Exploratory surgery revealed a mass in the region of the right testis that was excised and submitted for histology. The central bearded dragon had no post-operative clinical abnormalities. Grossly, the 6-cm diameter, smooth, yellow mass was composed of numerous, 0.5–3.0-cm diameter cysts filled with yellow fluid. Histologically, the cysts were lined by simple cuboidal to flattened epithelial cells that rarely formed small tufts or papillary projections. Cyst lumina occasionally connected with seminiferous tubules, approximately 10 % of which were dilated and all of which had normal spermatogenesis. Epithelial cells had a small amount of eosinophilic, slightly vacuolated cytoplasm, rare apical cilia and basilar, round nuclei with coarse chromatin and small, distinct nucleoli. This is the first description of a cystic rete testis in a reptile or any non-mammalian species. Cystic rete testis can be primary or secondary to obstruction of the efferent ductules or epididymis. The lack of inflammation and absence of diffuse dilation of the seminiferous tubules suggest that spermatozoa were able to escape, consistent with primary cystic rete testis.