PERMEABILITY OF STERLET SPERM MEMBRANES (ACIPENSER RUTHENUS L., 1758) FOR WATER MOLECULES

Purpose. The literature analysis of the results cryopreservation of different fish species highlights a variation of many parameters, in particular the sperm survival rate during the freezing and unfreezing process. The survival capability of spermatozoa may be called the main parameter, which indentifies the efficiency of the entire process of low temperature freezing of reproductive products. Therefore, the goal of this work was to investigate and find the causes of different degrees of fish sperm cryoimmunity, in particular that of starlet, which is a valuable of sturgeon (Acipenser) species. We also studies the possibility to find the optimum ways to improve the efficiency of the survival rate of the defrosted spermatozoa of different fish species for their further use to produce viable offspring. Methodology. The determination of sterlet sperm membrane permeability was performed after carrying out all necessary manipulations with brood males which included: prespawning incubation, hormonal stimulation, determination of sperm maturity degree, obtaining the sperm by stripping. The measurement of sperm membrane permeability for water molecules was performed based on the technique, which had been used earlier to measure carp sperm permeability, but taking account the specific peculiarities inherent to sterlet sperm. Findings. Based on the performed measurements, we determined the sterlet sperm membrane permeability for water molecules with the use of photometric method. The received experimental data show the highest degree of sterlet sperm membrane permeability for water molecules as compared to carp sperm membrane permeability. Originality. As a result of this experiment, we determined for the first time the absolute value of sterlet sperm membrane permeability for water molecules with the use of photometric method as well as compared the results with those obtained during our work with the carp sperm. Practical value. The data obtained during the experimental studies can be used in the practice of sperm cryopreservation for improving the efficiency of the sperm different of fish species during the process of low temperature freezing especially for such commercially valuable fish species as sturgens.