| Abstract: | The history of the germ cells is traced from the time of hatching. The germ cells are larger in size and have faintly staining cytoplasm, clear cell outline and a distinct nucleus. They migrate by ameboid movement to reach the genital ridge and aggregate to lie against the gonadal epithelium prior to the formation of gonads. The germ cells are distributed along the gonad primordia. The period of sex differentiation occurs between the 5.4 mm to 12 mm stage. The testis formation is recognized by the presence of germ cell nests and the sperm duct cord. The formation of the ovary is noted by the enlargement of the germ cells of uniform size and the development of the ovarian cavity. The ovaries are described in four stages ranging from 21 mm to 135 mm fish. At 21 mm stage the ovarian cavity is continuous but is obliterated at 35 mm stage due to the projection of the ovigerous lamellae. The common opening for both the ovaries develops at 35 mm stage. The testes are described in four stages ranging from 23 mm to 135 mm fish. They differentiate more slowly and the first maturation division is seen at 90 mm stage. |
