A.B. Burlakov - Dr. Sc. (Biol.), Professor, Leading Research Scientist, Department of Ichthyology, Lomonosov Moscow State University E-mail: burlakovao@mail.ru

The studies of the state central gonadotropocytes (GTZ) of the pituitary gland of females of silver carp Hypophthalmichthys molitrix with different fecundity from 33,000 to 1800000 oocytes, light and electron microscopic levels after stimulation of maturation of human chorionic gonadotropin. Showed that mature females in GTZ decreases the amount of secretory material. There is an intensive breeding as secretory granules and the contents of cisterns of granular endoplasmic reticulum. The formation of pituitary ovulatory waves of gonadotropin in females with different fecundity occurs varies due to the change in the ratio of processes, merocrine and holocrine secretion. From first maturing females of silver carp with fecundity less than 50,000 oocytes, the formation of the ovulatory wave of gonadotropins GTZ is only through merocrine (holocrine missing). Have re-maturing females in fertility 100000-500000 oocytes appears holocrine secretion in central GTZ (0.1% of the total number of cells in the smallest females to 1.2% in the larger). Have a 6-9 year old females in fecundity from 1000000 to 1800000 eggs in the formation of the ovulatory wave gonadotropin holocrine secretion undergo 6-9% central GTZ. Process merocrine secretion in GTZ fish with high fecundity is characterized by the appearance during the final stages of vitellogenesis giant elongated globules accumulate a huge amount of secretory material. Such globule formed by the fusion of smaller granules. During maturation of oocytes and preparation for ovulation giant globule moves to the shell of the cell, breaks through the shell and quickly displays its contents in the intercellular space "like a giant syringe". This leads to a very rapid flow of a large number of gonadotropin in the blood, allows to create a powerful ovulatory wave without involving the complete destruction of the GTZ (without holocrine secretion).

 

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