杂交鲆(牙鲆♀×夏鲆♂)胚胎发育的初步观察

Preliminary observation on the embryonic development of hybrid flounder(Paralichthys olivaceus ♀×Paralichthys dentatus ♂)

通过人工调控促使亲本牙鲆（Paralichthys olivaceus）♀×夏鲆（Paralichthys dentatus）舍的性腺发育，人工干法授精获得杂交受精卵。杂交受精卵在温度为16．5～17．5℃，光照为100-400lx，微充气条件下孵化。对杂交鲆胚胎发育全过程进行连续观察并与牙鲆度夏鲆的胚胎发育进行比较。结果表明：杂交鲆卵裂方式与其他大部分硬骨鱼类一样，属于盘状卵裂。受精后经过2h30min进入2细胞期，7h45min进入囊胚期，15h10min进入原肠胚阶段，25h30min进入神经胚期，49h左右进入尾芽期。授精后63h左右发现初孵仔鱼，68h左右50％的仔鱼孵出。在杂交鲆的胚胎发育中，主要有2个发育特征与母本类似而与父本不同：视囊的出现要早于体节的分化；孵化前，仔鱼在卵膜内环绕卵黄囊不到1周。但是在其孵化时间上却与父本相似。

The gonadal development and maturation of the broodstock Japanese flounder （Paralichthys olivaceus） and summer flounder （Paralichthys dentatus ） were induced by environmental manipulation. The fertilized eggs of hybridisation were acquired by artificial dry fertilization and hatched on the condition of water temperature ：16. 5-17. 5℃, intensity of illumination： 100-400 lx, and subtle aeration. The fertilized eggs are transparent and buoyant. The results show that the embryos of hybrid flounder belong to telolecithal egg and discoidal cleavage. The blastodisc appeared in 1.5 hours after fertilization. Eggs came into the cleavage stage in 2.5 hours, blastula stage in 7.75 hours, gastrula stage in 15, 17 hours, neural plate stage in 25. 5 hours and organogenesis stage in 28.5 hours after fertilization. At the time of 68 hours after that of fertilization, fifty percent of embryos hatched. There were two major developmental characteristics similar to that of the female parent other than that of the male parent： optic vesicle stage prior to the formation of the somites; the larval wraped the yolk sac within one perimeter before hatching. Interestingly, the incubating period of the eggs was similar to that of the male parent, and different from that of the hybrid eggs of other fish species whose incubating period was similar to that of the female parent.