Effect of desiccation in shade on in vitro oocyte maturation and development of the sea cucumber Apostichopus japonicus (Echinodermata: Holothuroidea).

Techniques for in vitro oocyte maturation are important for studying maturation regulatory mechanisms, cell differentiation, and embryonic development. In this study, after Apostichopus japonicus gonads were dissected, oocytes, together with gonadal fluid extracted from gonads, were dried in shade. The effects of three temperatures (17, 21, and 25 °C) on oocyte maturation and following development were studied. The results showed that germinal vesicle breakdown (GVBD) of most oocytes occurred after desiccation, and those oocytes with GVBD could be fertilized and develop normally. There were no significant differences in the percentages of GVBD and individuals in blastula and gastrula stages between 17 and 21 °C (p >.05). The percentages of GVBD reached a maximum (17 °C: 98.6%, 21 °C: 97.1%) after 2 h of desiccation. The percentages of blastulae and gastrulae reached the maximum of more than 80% after 2.5–3.5 h of desiccation. At 25 °C, the percentages of GVBD, blastulae, and gastrulae reached a maximum of 76.7, 61.0, and 59.9% after 3.5 h of desiccation, respectively, and were significantly lower than that at 17 and 21 °C (p <.01). This study not only provided an effective and simple technique for in vitro induction of A. japonicus oocyte maturation, but also furthered understanding of gamete biology of this species. [ABSTRACT FROM AUTHOR]