REGULATION OF MEIOSIS IN THE MAMMALIAN OOCYTE CULTURE - THE ACTION OF HORMONES AND GROWTH-FACTORS

The role of some intraovarian regulators of the final stages of gametogenesis is analysed. It is shown that the epidermal growth factor (EGF) in concentration of 1 and 10 ng/ml is able to induce reinitiation of meiosis from dyctiotene stage during cultivation of the ovarian follicles of prepuberal mice in the serum-free medium after gonadotrophic stimulation. The pattern of maturation was analogous to that of maturation after HCG (LH) administration. Also, the EFG is able to stimulate meiosis reinitiation in the culture of cumulus-free oocytes blocked with cAMP at the stage of dyctiotene. At the same time fibroblast growth factors and insulin do not demonstrate such an activity. Taking into consideration a high sensibility of oocytes to the EGF action, and also the fact that the character of changes of steroid hormones secreted by the ovary in culture under the action of EGF is the same as that under the influence of LH it is suggested that, the EGF and EGF-like proteins secreted by somatic follicle cells are the paracrinic regulators of the mammalian oocyte maturation which modulate neuroendocrine factors of the oogenesis control.