光裸方格星虫(Sipunculus nudus L.)生殖细胞及胚胎发育

Development of Genital Cells and Embryo of Sipunculus nudus L.

关键词:  光裸方格星虫  生殖细胞  繁殖期  胚胎发育

Key words:  Sipunculus nudus  genital cell  breeding period  embryonic development

摘要:

1990年3月至1991年2月,每月采样1~2次,每次取30条个体,在显微镜下观察雌雄生殖细胞的发育和形态特征。计数雌性个体体腔卵细胞。1990年6月~7月取体重≥13 g的个体,解剖取肾管中的精卵进行人工授精,观察胚胎发育进程。取部分担轮幼虫于10 L容器中(水温27.5℃~29℃,海水比重1.017~1.019)培养,观察早期个体发育。结果表明,光裸方格星虫雄性生殖细胞以细胞团形式存在,卵细胞以单个游离存在。卵细胞分5个发育期。各期卵细胞相对含量的周年变化表明光裸方格星虫属分批产卵类型,产卵期为4月~9月。光裸方格星虫的精卵只有经肾管收集后才具受精能力。受精卵约经3 h发育为担轮幼虫,经24 h左右发育为海球幼虫。担轮幼虫为卵黄营养型。海球幼虫为浮游生物营养型,摄取单细胞藻类或有机碎屑为食,浮游生活2~3周后变态为稚星虫。

Abstract:

Sipunculus nudus was sampled one or two times each month from March 1990 to February 1991.Thirty individuals each time were dissected to observe the development of male and female genital cells by microscope. Oocytes of female coelom were counted.The sperm and oocyte in nephridioduct were took out from the samples (weight ≥ 13 g) to observe the embryonic development in June and July 1990. Part of pelagosphere was cultured in 10 L container at water temperature 27.5℃ to 29℃,water specific gravity 1.017 to 1.019 to observe the early individual development.The results were as follows.The male genital cells were group and egg cell was single.The egg cells had five stages.S. nudus spawned in patches according to the annual fluctuations of relative content of oocytes in different stages.The breeding period is April to September.The genital didn't have fertilization until being collected by nephridioduct.The zygote grew up to trochosphere after 3 h and to pelagosphere after 24 h.The trochospere relyed on yolk sac, while the pelagosphere relyed on plankton and became naiad with intake of microalgae and organic about 2 or 3 weeks.