HISTOLOGICAL STUDIES ON THE DEVELOPMENT OF OVARY OF COLOSSOMA BRACHYPOMUM

The development of the ovary and the electronic microscopy of the structure ofmature ovum of the fish, Colossoma brachypomum Cuvier were studied. The ovary in those fish under two-year old remains at Stage I, and at Stage II for those fish between 2 and 3 years old. The female fish reaches sexual maturity above three years old, During Stages IV, V, VI, the oocytes are mainly in phases 4 and 5 with a few in phases 2 and 3. It is evident that the oocyte development of the fish is continuous and the repreduction of the females may be manipulated artificially many times within a year. The changes in the structure of oocytes during the development were also examined. It is further suggested that C. brachypomum belongs to the type of poly-spawning fish.