Mechanisms of multiple spawning of teleosts

硬骨鱼类性腺成熟机制的许多信息已经收集使用单个产卵物种，如鲑鱼，作为一个模型。本研究以多产卵的红点？作为多产卵的模式鱼.短生殖周期中促性腺激素细胞精细结构的变化：短生殖周期分为三个阶段：排卵前、排卵和产卵后。只有一种类型的促性腺激素被观察到在垂体的近端远侧部。在整个周期中，小颗粒的大小和数量变化不明显，而大颗粒的大小变化很大，其直径在排卵前为13000-15000*，到产卵期增大到15000-28000*，到产卵后减小到7500 -12500*.短生殖周期卵巢体外类固醇激素分泌的研究：将卵黄积累的卵母细胞分为两组，排卵前大卵母细胞（LO，较长直径1.2-1.7 mm）和小卵母细胞（SO，0.6-1.1 mm）。LO或SO与或不与鲑鱼垂体提取物一起孵育（SPE ; 10或100 μ g/ml）或孕马血清促性腺激素（PMSG ; 10或100 IU/ml）。在产卵后的鱼中，LO和SO产生几乎相同量的雌二醇17 β（E2 ;卵黄产生刺激类固醇）和17，20 β-二羟基-4-生育烯-3-酮（17，20 β- P ;卵母细胞成熟诱导类固醇）根据外部促性腺激素的管理。而在排卵前，SO的E_2产生量远高于LO，而LO则在促性腺激素刺激下产生大量的17，2 O β-P。

Much information on the mechanisms of gonadal maturation in teleosts has been collected using single spawning species, such as salmonids, as a model. In this study the rose bitterling Rhodeus ocellatus ocellatus, a multiple spawning cyprinid was used as a model for multiple spawners.1. changes in fine structure of gonadotrophs during short reproductive cycle : Short reproductive cycle of the bitterling was divided into three phases ; pre-ovulation, ovulation, and post-spawning. Only one type of gonadotroph was observed in the proximal pars distalis of the pituitary. Throughout the cycle, the size and number of small granules did not change significantly.However, the size of large globules (LG) changed drastically ; the diameter of LG was 13000-15000* in the pre-ovulation phase, then it increased to 15000-28000* in the spawning phase, and decreased to7500-12500* in the post-spawning pahse.2. In vitro steroid production in the ovary during short reproducitve cycle : Yolk accumulated oocytes were divided into two groups ; pre-ovulating large oocytes (LO, longer diameter 1.2-1.7 mm) and small oocytes (SO, 0.6-1.1 mm) .LO or SO were incubated with or without salmon pituitary extract (SPE ; 10 or 100 mug/ml) or pregnant mare serum gonadotropin (PMSG ; 10 or 100 IU/ml) . In the post-spawning fish, both LO and SO produced almost the same amount of estradiol 17beta(E2 ; yolk production stimulating steroid) and 17, 20beta-dihydroxy-4-pregnen-3-one (17, 20fbeta- P ; oocyte maturation inducing steoid) in accordance with the administration of external gonadotropin. In the pre-ovulation fish, however, the production of E2 was much higher in SO than that in LO.In contrast, LO produced large amount of 17, 2Obeta-P compared to that produced by SO in response to gonadotropin administration.