[Effect of low temperature on 3H-uridine incorporation in oocytes of tilapia mossambique].

Using 3H-uridine dynamics of RNA synthesis in oocytes of tilapia which grow at different temperatures was studied. Intact fishes were cultivated at the temperature 25-26 degrees C, experimental ones -- 19-21 degrees C. Before 3H-uridine injection, experimental fishes were cultivated at low temperature for 5 days, then both intact and experimental fishes were injected by 3H-uridine and experiment was continued for 5 days.

[Oogenesis of Mozambique tilapia. IV. Yolk formation].

Yolk globules in developing oocytes of Tilapia mosambique are formed by two processes: 1) biosynthetical activity of oocyte organoides; 2) vitellogenin migration by micropinocytosis and its further transformation. Undoubtedly, yolk globules of endogenic and exogenic origin are fused. The primary yolk globules are spherical, and the secondary ones are lobular.

[Oogenesis of Tilapia mossambica. III. The cytoplasm of previtellogenic oocytes].

Using methods of light and electron microscopy and of autoradiography, the morphology of cytoplasm in previtellogenic oocytes of tilapia mossambique was studied. Similar to other bony fishes, mitochondria at the early previtellogenic oocytes are mostly located in the perinuclear cytoplasm to be later distributed over the whole volume of growing oocytes. The Golgi complex is poorly developed.

[Oogenesis of Mozambique tilapia. II. Synthesis of RNA and development of the nucleoli].

Using methods of light and electron microscopy and authoradiography, morphology and biosynthetic activity of nucleoli and RNA synthesis in developing oocytes of Tilapia mossambique were studied. In previtellogenic oocytes nucleoli are mostly composed of fibrils, while the granular component is poorly developed. 3H-uridine is poorly incorporated in their peripheral parts.

[Oogenesis of Tilapia mossambica. I. Oogonia and meiotic prophase oocytes].

Using light and electron microscopy and autoradiography, the morphology and synthesis of DNA, RNA and proteins in oogonia and early meiotic prophase oocytes in Tilaria mossabique were studied. According to dimensions and morphological features observed it is possible to distinguish between two groups of oogonia: large oogonia corresponding to type A spermatogonia of mammals, and small actively dividing oogonia, located in groups and identical to type B spermatogonia. The morphology of oogonia and of the early meiotic prophase oocytes well compares with the pattern described for other species of bony fishes.