About resorption of previtellogenesis oocytes in cyclostomes and fish

The aim of work is to analyze the features of previtellogenic oocyte resorption in cyclostomes and fish. The method used is a generalization of our own and literature data. Novelty. For the first time, the data on the resorption of previtellogenic oocytes have been systematized. Results. According to the accumulated data, oocytes of this period are resistant to external influences and do not undergo resorption even before the immediate death of the experimental fish. At the same time, the facts of resorption of individual oocytes are well known and are associated with their initial non-viability. At the first stage of destruction, such cells are distinguished by an intense color — pycnomorphic cells, and at the final stage they disintegrate into separate fragments. External influence and the associated energy deficit only accelerates the destruction of such cells. When studying juveniles of salmonids of all species, numerous facts of loss of shape by previtellogenic oocyte were revealed. Since the destruction of such cells does not occur, and no further decrease in their number is observed, it can be assumed that such compression is an artifact of histological processing. At the same time, mass resorption of previtellogenic oocyte has been described and is the initial stage of either the formation of the value of absolute fecundity during the transition to another life form, or a reduction in the number of individuals in a species with cyclical population dynamics. Practical significance. The results of the analysis will give the authors a basis from different positions to consider the facts of changes in the shape of previtellogenic oocytes during both experimental and field studies. It can be assumed that external extreme, but relatively short-term impact on juvenile fish during previtellogenesis will not lead to a change in the value of absolute fecundity.