Anatomy of finfish and shellfish

Unit 8 - Urino-Genital System

8.4.4. Bony Fishes
In most of the bony fishes testis are whittish, lobulate organs, lying along the gas bladder, although in some groups such as Salmonids, the organs are smooth and entire without lobules. In most of the forms, there is no connection at all between the reproductive openings to the exterior for the two systems with the urinary pore posterior to the genital pore.
In some the sperm ducts connects with the urinary system in a urogenital sinus located at the posterior end of the body cavity. Ovaries of bony fishes are typically saccular and continue with the oviduct.
Interesting exceptions to this system involves the more primitive forms viz., Acipenser, Polydon and Amia all shed eggs from the incompletely covered ovaries into the body cavity. Eggs are caught by a coelomic funnel opening partially from the back of the ovary and conveyed through the oviduct.
Other exceptions are seen in the Smelts, Salmonids, Eels and few others, none of which have saccular (A hallow or bag or a pouch and a flexible structure in the body). Ovaries continue with oviducts. Smelts have coelomic oviduct with funnels opening behind the ovaries. Salmonids show incompletely enclosed ovaries and extrude eggs though a very short funnel leading to a pore just anterior to the urinary pore. Eels have no funnels; the eggs simply pass out through a pore. The ovaries of fishes are usually well separated, but fusion of the right and left organs can be seen in some Percoids (fishes of the family Parciformes). In large mouth bars, the ovaries join posteriorly to produce a “V” shaped structure. Ovaries of the yellow perch, Perca flavaseens are so completely fused so as to give the appearance of a single organ. This ovary is fused to the body wall just posterior to the anus and eggs are extruded when this area ruptures, so those oviducts are not functional. The rupture of the body wall heals soon after oviposition.