The urinogenital organs of Wallago attu

Sinha, B. M.

The paired kidneys are indistinguishably fused. Each consists of a head kidney in front of the air bladder and a posterior kidney behind it, which are connected by strands of nephrogenous tissue. The head kidney is non-excretory and is without urinary tubules, while the posterior kidney is excretory and contains the urinary tubules and malpighian capsules. The ureters are pronephric ducts, which get secondarily connected with the kidneys. They fuse before opening into the urinary bladder. The paired gonads lie below the posterior kidneys. The testis is strap-shaped and divided into lobes produced towards the outer side into processes. The lobules are lined with germinal epithelium the cells of which proliferate and undergo spermatogenesis. The ovary is a sac of connective tissue produced into folds towards the cavity of the sac, which run in parallel rings. The folds contain mature ova towards the center and young ones on the periphery. The genital ducts are the continuation of the peritoneum covering the gonads. A single oviduct is present in the female, while there is a pair of vasa deferentia in the male. A pseudocopulatory papilla is present behind the anus. The papilla is traversed by the urinogenital duct separated into a dorsal urinary and a ventral genital passage. The urinary passage is involuted and is lined with columnar cells, while the genital passage is smooth and is lined with flat cells. The urinary and genital passages open independently in female and by a common aperture in male. The sexes are separate and sexual dimorphism exists to some extent. The spine of the pectoral fin is more strongly developed and more deeply indented in the male than in the female. The pseudocopulatory papilla is slender and pointed in the male, while it is broadly built and truncated at the apex in the female.