Grober M S, Jackson I M, Bass A H
Section of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853.
J Neurobiol. 1991 Oct;22(7):734-41. doi: 10.1002/neu.480220708.
In diandric sex-reversing fishes, sexually active males and females (primary phase) regularly transform into an alternative reproductive morph, terminal-phase males, that are morphologically and behaviorally distinct. The transformation from primary to terminal phase is associated with a twofold increase in the number of luteinizing hormone-releasing hormone (LHRH) immunopositive cells in the forebrain preoptic area, a region involved in both the initial development and daily control of reproductive physiology and behavior. We now show that implants of 11-ketotestosterone induce increases in LHRH cell number in both primary phase sexes to the level observed in field-collected terminal phase males. Conversely, gonadal steroids had no effect on the number of LHRH preoptic cells in terminal phase males, suggesting that this is indeed a terminal stage in the development of this species. These results demonstrate that transition to the terminal phase by both sexes involves a parallel and convergent change in LHRH cell number, which utilizes an evolutionarily conserved mechanism of sexual differentiation: the inductive effects of gonadal steroid hormones.
在具有双性性逆转的鱼类中，性活跃的雄性和雌性（初级阶段）会定期转变为另一种生殖形态，即终期雄性，其在形态和行为上都有所不同。从初级阶段到终期阶段的转变与前脑视前区中促黄体生成素释放激素（LHRH）免疫阳性细胞数量增加两倍有关，该区域参与生殖生理和行为的初始发育及日常控制。我们现在表明，植入11-酮睾酮会使初级阶段两性的LHRH细胞数量增加到在野外采集的终期雄性中观察到的水平。相反，性腺类固醇对终期雄性视前区LHRH细胞数量没有影响，这表明这确实是该物种发育的一个终期阶段。这些结果表明，两性向终期阶段的转变涉及LHRH细胞数量的平行且趋同的变化，这利用了一种进化上保守的性分化机制：性腺类固醇激素的诱导作用。
