利用组织学方法研究了瘤背石磺体重（2—28 g）与性腺发育、性腺指数与肝胰腺指数或卵黄腺指数间的关系，不同体重瘤背石磺性腺内各期生殖细胞的组成与比例以及瘤背石磺卵子和精子发生的规律。结果表明，（1）瘤背石磺的性腺指数有随体重增加而增加的特点：10 g以上个体性腺指数达到最高且基本无变化；不同体重瘤背石磺性腺指数与肝胰腺指数和卵黄腺指数有明显的正相关性（P<0.05）；（2）6 g以下组的瘤背石磺性腺滤泡管内未发现有雌性生殖细胞，6 g以上组的性腺滤泡管内雄性与雌性生殖细胞并存；（3）所有瘤背石磺个体性腺内均有精子分布，6 g以下个体雄性生殖细胞组成以次级精母细胞为主，而6 g以上个体则以精子为主；6 g以上组的雌性生殖细胞成熟程度随体重增加有明显增加，其中6—8 g以卵原细胞为主（57%），8—10 g开始出现外源性卵黄合成期的卵母细胞，10—14 g时的外源性卵黄合成期的卵母细胞约为69%，且开始出现成熟卵母细胞。（4）卵子发生共经历6期：分别为卵原细胞期、卵黄合成前卵母细胞期、内源性卵黄合成期、外源性卵黄合成期、近成熟期和成熟卵母细胞期，成熟卵母细胞直径约为(59.36±3.88)μm。精子发生经历精原细胞、初级精母细胞、次级精母细胞、精子细胞和精子共5个阶段，精子长约(52.44±20.65)μm。石磺体重与性腺发育程度密切相关，10 g以上的个体可做为亲本使用。
The relationship between body weight and gonad development of Onchidium struma was studied using a histology method. The relation between the gonadsomatic index (GSI) and hepatopancreas somatic index (HSI) or vitelline somatic index (VSI) were also studied. The composition of germ cells and the percentage difference of phases of germ cells in gonads were analyzed. Spermatogensis and oogenesis of O. struma were observed. The results showed: (1) The development of gonads in O. struma matured as body weight increased. The GSI and HIS or VSI had obvious pertinence respectively（P<0.05）. (2) The oocytes appeared in individuals whose body weight was above 6 g and from this time the oocytes and sperm cells coexisted in the gonads. (3) The spermatozoa were found in all individuals. The main germ cells were the secondary spermatocyte in individuals whose body weight fell under 6 g and those with body weights above 6 g had spermatozoa. The individuals who were above 6 g; the oocytes matured as body weight increased. The main elements of the germ cells were oogoia (57%), exogeous vitellogenic oocyte(69%) in the 6-8g individuals and 10-14 g individuals respectively. The mature oocytes were first found in the 10-14 g individuals. (4) The oogenesis can be divided into 6 stages: oogoia，previtellogeic oocyte，endogenous vitellogeic oocyte，exogeous vitellogenic oocyte，nearly-mature oocyte and mature oocyte (Φ=59.358±3.88 μm). The spermatogensis consisted of five stages: spermatogonia，primary spermatocyte，secondary spermatocyte and spermatozoa (52.44±20.65 μm). We can conclude our research in two points: (1)There is a relationship between body weight and development of gonads. (2) The individual with a body weight above 10 g can be a parent.