A preliminary study on process of sex reversal in Eleutheronema tetradactylum

In this study, we studied the morphological and sex ratio statistics of artificially cultured Eleutheronema tetradactylum, and observed their gonads by morphological and histological methods. The results show that when the salinity was 10.8–13.0 and the water temperature was 28.0–30.7 ℃, male, female and hermaphrodite accounted for 85.53%, 5.70% and 8.77%, respectively in the 228 samples at age of 7 months. Besides, there was no significant difference in the body mass, total length, body length and body height among the three individuals. Anatomic observation shows that the two dorsolateral sides of androgynous gonads were white testis, and the two ventrolateral sides were ovaries which were yellowish and reddish. Histology shows that the mature sperm formed on the testis side, which is Stage IV or V feature of typical testis, and the ovary side had an ovarian cavity, mainly oocytes and early phase II oocytes, which were typical phase II characteristics of ovary. Thus, it can be concluded that E. tetradactylum is a protandrous hermaphrodite. The process of sex reversal can be divided into three stages: early, middle and late. The ovary structure gradually formed and developed into Stage II ovary, which is the main feature of tissue structure change. However, the testis structure gradually degenerated and disappeared. The apoptotic cell signal of the testis has been detected during the whole sex reversal process.