Abstract
The morphology and histology of the catfish (Parasilurus aristotelis) testes were studied during the spawning period (March to August). Unlike other typical catfish, the testes of P. aristotelis are devoid of seminal vesicles. Both the cranial and caudal regions have a similar structure, with spermatogenic rather than secretory function. The main sperm duct of each unpaired testes is unusual in being divided into two parts: an upper one lined with germinal epithelium; and a short lower section lined with cuboidal epithelium. The seasonal reproductivity in this catfish is less pronounced than in other species. Its breeding season is protracted with continuous, asynchronous spermiogenesis. The testes histological structure resembles that of other teleosts. Observations revealed highly significant correlations (p<0 .01;p<0.001) between: male body length and quantity of seminiferous tubules in a unit area of sectional surface; diameter of seminiferous tubules and their quantity; weight of testes and diameter of seminiferous tubules; and total number of seminiferous tubules vs. sperm-laden tubules.
