Comparative stages of atretic oocytes between Episesarma versicolor and E. singaporense from Thailand: Implication on the reproductive success

Abstract

Informative reviews on the oocyte atresia referring to degeneration and resorptive mechanism are warranted in common animals, but it is rarely still found in carbs. In this current study, we focused on characteristics and stage of the atretic oocyte from two important female sesarmid carbs (violet vinegar crab, Episesarma versicolor, and Singapore vinegar crab, E. singaporense) during ovarian maturation. A total of 30 female samples in each carb species were collected from the Palian mangrove area of Trang province, Thailand. The results shared among those carb samples that both primary growth (PGs) and secondary growth (SGs) phases underwent a degenerative process of atresia. The latter of atresia during SGs was also divided into five stages (I, II, III, IV, and V). The degeneration of follicular cell and yolk architecture identifying in the SGs were highlighted. The number of atresias was slightly compared between E. versicolor and E. singaporense; therefore, there were no significant differences. Our observation suggested that the low number of atresia might be associated with the increased reproductive success of two female sesarmid carb living in natural habitats.