Abstract
Abstract: It was recently reported that oocytes have no cortical crypts even in the pre-maturation and mature stages in the small penaeid shrimp Metapenaeopsis dalei. To determine whether this is a general feature in the oogenesis of the species of Metapenaeopsis, the morphologies of the oocytes of M. aegyptia, M. barbata, and M. sinica were observed histologically in the present study. Fairly developed yolk-granule stage and pre-maturation stage oocytes(Stages V and VI)were observed from early summer to autumn when the gonad somatic index was high, but mature oocytes were never observed throughout the year. No cortical crypts were observed in the late phase of the pre-maturation stage oocytes(Stage VI). Oocytes at the yolk-granule stage and the early phase of the pre-maturation Stage V were simultaneously observed with Stage VI oocytes in the same histological sections. These results seem to indicate the absence of cortical crypts through oogenesis and the occurrence of multiple spawning at short intervals in all three species, similarly to M. dalei. Such features might thus be general for the genus Metapenaeopsis.
