State of steroid secretory cells and concentration of gonadal steroid hormones in the blood plasma of Siberian sturgeon Acipenser baerii and sterlet A. ruthenus (Acipenseridae) during sex differentiation

Results of studying steroid secretory cells in gonads and the level of estradiol-17β and testosterone in the blood plasma of young Siberian sturgeon Acipenser baerii and sterlet A. ruthenus, aged 8.5 and 9.5 months, respectively, is studied. During sex differentiation, the steroid secretory activity in females is intensified first in the stroma of gonads and then, after the formation of oocytes during the previtellogenesis period, it is shifted to the follicle theca. The development of oocytes is accompanied by a decrease in the concentration of testosterone and an increase in the concentration of estradiol-17β. In males, the intensification of the activity of steroid secretory cells, which was indirectly determined by the state of organoids, is accompanied by an increase in the concentration of testosterone in blood plasma.