瘤背石磺产卵前后生殖系统的组织学变化

瘤背石磺(Onchidium struma)是雌雄同体、异体交配的腹足纲贝类,其生殖系统较为复杂,通过解剖学和组织切片技术对成体瘤背石磺的生殖系统及产卵前后的组织学变化进行了系统的研究.结果表明:(1)雄性生殖系统主要南阴茎囊、阴茎、雄性附性腺、两性腺(早期主要产生精于)和储精囊等部分组成,而雌性生殖系统则由两性腺(后期主要产生卵子)、生殖细胞输送管、蛋白腺、黏液腺、受精囊和阴道等组成;(2)雄性生殖系统的组织学结构在产卵前后变化较小,但两性腺、卵蛋白腺和黏液腺的组织学在产卵前后变化显著;(3)产卵后的两性腺由于成熟卵子的排放,整体结构松散,部分腺泡中有少量未排出的成熟卵细胞和卵黄合成早期的卵母细胞;(4)产卵前的卵蛋白腺中含有许多强嗜碱性的小颗粒(组织学结构类似于卵鞘中的胚胎外周蛋白),产卵后腺体中的颗粒相对较大,且呈嗜酸性;(5)产卵前的黏液腺中存在嗜碱性区、嗜酸性区和混杂区三种区域,但是产卵前黏液腺以嗜酸性细胞为主,而产卵后的黏液腺中以嗜碱性细胞区域为主,且分泌管道中有一些嗜碱性物质.由此可见,卵蛋白腺的主要功能是分泌卵蛋白包裹受精卵形成卵外周蛋白层,而黏液腺则在产卵过程中分泌黏液物质形成卵鞘结构及链状的卵带.

The histological changes of reproductive system between pre- and post spawning Onchidium struma

Onchidium struma is a very important mollusk with high nutritional and pharmic value, which distribute on the mudflats of the intertidal zone of China, especially in Jiangsu, Shanghai and Zhejiang Province. Although there is an increasing demand for the aquaculture of this species, the reliable hatchery technology has not been established in China because of its complicated reproductive system and unclear early life history. Therefore, it is very urgent to understand its reproductive system and spawning process, unfortunately, only two available studies have been conducted to study the composition of its reproductive system, and no publication could be found on the histological changes of reproductive system during the spawning process of O. struma. So, the present experiments were conducted to investigate the histological changes of reproductive system between pre- and post spawning O. struma. After that, the composition and function of reproduction system (gonads and accessory sex organs) were further discussed in this paper, which should provide valuable information to understand reproductive process and improve hatchery technology of O. struma. The results indicated that: (1) The male reproductive system included penis, penial sac, male prostate, digenetic gonad (mainly produce sperm in early stage of gonad development) and sperm bursa, while female reproductive system was consisted of digenetic gonad (mainly produce mature oocytes in late stage of gonad development), gametal transportation tract, egg albumen gland, mucous gland, fertilization chamber and vagina; (2) Although there was no significant difference of male reproductive system between pre- and post spawning O. struma, the significant differences could be found on the digenetic gland, egg albumen gland and mucous gland; (3) After spawning, the digenetic gland became loose while the un-spawned mature oocyte and the early previtellogeic oocyte were found in some follicles; (4) Before spawning, the egg albumen gland consisted of many small basophilic granules which structure was very similar to the outer albumen of the embryo of O. struma. However, after spawning, the egg albumen gland contained bigger acidophilic granules than those before spawning; (5) Before spawning, there were acidophilic, basophilic and mixed area in the histological section of mucous gland while the basophilic area were dominant in the post-spawning mucous gland and the basophilic substance could be found in its secretion tube. In conclusion, these results suggested that the egg albumen gland could secrete protein to pack fertilization egg, and then to form egg albumen while the mucous gland generated mucus to encapsule and link embryo.