Insulin participation in regulation of organism growth function was undoubtedly proven during the last several years. Many evidences suggest that its crucial role in development appear in very early stage of embryo maturity. Our works aim was to investigate the changes of the insulin receptor kinetics in rabbit fetus livers during the last week of gestation. Dissociation rates constants (KD) and binding capacities (Bmax) for insulin on the isolated liver membrane fractions were determined. The maximal specific binding was observed between the days 25 and 28 of gestation. HAIR’s maximal binding was observed in days 25–26 and 29–30 of pregnancy. Maximal binding of the LAIR occurred earlier-between the 23rd and 26th day. The obtained results show insulin receptor activity increase parallel to the embryo weight raising during the period of intensive cell proliferation.

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