OOGENESIS OF TILAPIA MOSSAMBIQUE. IV. YOLK FORMATION
D. A. Chmilevsky, T. O. Kameneva
Biological Research Institute, St. Petersburg State University, and Institute of Cytology RAS, St. Petersburg;
e-mail: ichtyoll943@mail.ru
Yolk globules in developing oocytes of Tilapia mossambique arc formed by wo processes: 1) biosyn-thetical
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. The latter originate by incorporating the former. The fast growth of the late
vitellogenic stage oocytes occurs as a result of active migratior of primary yolk globules into the central part of
the oocyte and as their association with the secondary yolk globules. In vitellogenic oocytes of T.
mossambique no yolk vesicles (cortical granules), were found by any existing methods.
Key words: vitellogenic oocytes, Tilapia mossambique, oogenesis, yolk globules
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