[Histophysiological analysis of adaptation of ecologically different species of sturgeons to hypertonic medium]

In saplings of Acipensar güldenstädti Brandt while adapting to sea water with salinity of 12.5%, the main functional changes in the chloride cells of the branchiae, the thyroid gland and interrenal tissue occur within the first 12 hours. During this period, concentration of osmotically active substances in blood serum increases (the first stage). Adaptive decrease of this concentration (the second stage) takes place after activation of the endocrine glands and transition of the chloride cells into excretory state that stipulates, in fact, the change of osmoregulatory type in fish for the transition from fresh water into hypertonic medium. After activation, the endocrine glands return to moderately active state. Adaptation of Acipenser baeri stenorrhynchus var. baicalensis to sea water with salinity of 12.1% produces isoosmotic changes in blood serum to the external medium.