To the question of variability of number of micropyles in oocytes of ship sturgeon (Acipenser nudiventris)

The paper considers the characteristics of the gametes, habitats and spawning conditions of sturgeon, which are important for improving the biotechnology of their artificial reproduction. Based on the native data and literature, there have been analyzed the limits of variation of micropyle of ship sturgeon (Acipenser nudiventris Lovetsky, 1828) and some other species, as well as the features of the micropylar complex. The material for the study conducted in 2018-2019 served the ovulated eggs and caviar from the broodstock of the second-third generation of ship sturgeon, which contained in the conditions of the State Regional Centre for Sturgeon Gene Pool Conservation “Kubanbioresursi”. Ship sturgeon has been found to have the largest average number of micropyles among low-chromosomal species. In the main sample, the number of micropyles varied from 2 to 41, with an average value of 11.09 ± 0.24 and a concentration of indicators from 2 to 19 (94%). The location peculiarity and a slight variation in the number of micropyles in one female species of ship sturgeon have been revealed, as well as the different shape of a micropylar complex, as opposed to the similar shapes in other sturgeon species: ship sturgeon has not the funnel-shaped micropylar complex, but the bowl-shaped one. The ship sturgeon spawns under conditions of high water speed and a micropylar bowl, the diameter of which exceeds 2-3 times the diameter of the funnel and increases the collection area of the highly diluted seminal fluid. From a practical point of view, studying these features is important for improving the biotechnology of artificial insemination of roe of rare species in conditions of almost complete absence of natural reproduction in natural conditions.