可口革囊星虫生殖周期的观察

Observation on the reproductive cycle of Phascolosoma esculenta

通过对可口革囊星虫体腔生殖细胞的发育和形态特征的周年观察,逐月统计体腔卵母细胞的数量,研究其变化趋势。结果表明,可口革囊星虫雌雄异体,性比为1∶1,无可见的生殖腺结构,原生殖细胞在体腔液中发育。体腔内全年都有生殖细胞存在,排卵期与产卵期出现重叠现象,卵母细胞分批成熟,分批产卵。根据卵母细胞的形态特点和存在方式可分为5个发育阶段：细胞增殖期、细胞质生长期、胶质膜形成期、成熟前期和成熟期。雄性生殖细胞在成熟之前,以细胞团的形式存在于体腔液中,其发生和产出过程,在时间上与卵母细胞同歩。成熟的生殖细胞经肾管排出、体外完成受精。宁德地区可口革囊星虫的生殖季节为5-9月,其中7-8月为繁殖盛期。体腔卵母细胞的长径与短径呈线性关系：Y=1.14X-0.7316（R2=0.9711）。

In this study the morphological features on the germ cells of peanut worms （ Phascolosoma esculenta） have been investigated by means of biological microscope for an annual period. A monthly calculation has been done to scrutinize the variation tendencies of number of oocytes of different developing stages. It has been clearly demonstrated that all individuals observed were dioecious, but they lacked permanent gonads, and the sex ratio was 1 ： 1. The formations of eggs and sperms were from the lining of the body cavity to the bottom part of the worm. The dissociated germ cells multiplied and developed in the coelomic cavity. The periods of ovulation and spawning overlapped. Oocytes developed into maturation by the time, and then spawned in batch. The development of oocyte could be divided into five stages： oocyte multiplication, plasmic growth, gelatinous membrane formation, pre-mature and mature stage. Sex cells in the male were present in the coelom in shape of a round lump before maturation, and the process of development from spermatogonia to specmatozoa was consistent with that of the oocytes. They broadcasted their gametes into the surrounding water, where fertilization occured. The spawning of this population in Ningde＇ s sea area took place several times from May to September each year and peaked from July to August. The linear relation between egg length and egg width is Y= 1.14X-0. 731 6（R^2 =0.9711）.