Histological and histochemical observation on ovary development in oriental river prawn Macrobrachium nipponense

In the study, histologic section and histochemical methods were used to research the organizational structure of female reproductive system and ovary development cycle in oriental river prawn Macrobrachium nipponense.The results show that the female reproductive system is composed of ovary and oviduct, and the ovary is covered with connective tissue capsule and reproductive epithelium. The ovarian development of oriental river prawn has significant changes in color and volume, therefore, according to the external shape and internal structure, ovarian development can be divided into five stages, including multiplication stage, minor growth stage, major growth stage, maturation stage and recovery stage. Oogenesis can be divided into four stages: oogonium stage, previtellogenesis stage, vitellogenesis stage, late vitellogenesis stage. The previtellogenesis oocytes is regarded as niche long-term primary oocyte, the cytoplasmic is filled with basophilic cells and no yolk granules. The vitellogenesis oocytes is the huge growing oocytes, the cytoplasmic is filled with eosinohilic cells, the early vitellogenesis oocytes contains yolk granules and blocks late into yolk, the nucleus is located in the central of oocytes. The period of the oocytes has been mature with great volume in the late vitellogenesis stage, nuclear moves to the surrounding of the oocyte, eventually the germinal vesicle breakdowns and the nuclear membrane disappeares, the egg around follicular cell layer becomes extremely thin, waiting for ovulation.