Overripe caviar are caused by a long delay in the female's cavity due to the lack of necessary environmental conditions during the breeding season, characterized by low fertilization, the appearance of a large number of deformities, a large waste during incubation.

With postovular overripeness, large yolk granules move into the animal part of the oocyte and coalesce into large clumps with the cytoplasm between them. The cortical alveoli flatten and become elongated parallel to the oocyte shell on sections. The ultrastructure of oocytes is significantly disturbed - the clarity of membrane structures is lost, mitochondria acquire greater density, crystals in them become less pronounced or indistinct. Vesicles of the endoplasmic reticulum and mitochondria lose their clear contours and their membranes become more tortuous. In some areas of the cytoplasm, organelle membranes and organelles themselves may disappear. The structure of the shell also changes significantly. If the eggs in the follicle are overripe, the destructive changes in the egg that is still capable of ovulation are close to those observed in post-ovulatory overripening.