东北七鳃鳗早期发育研究

通过开展东北七鳃鳗(Lampetra morii)胚胎、卵黄囊期仔鱼和幼鱼发育研究, 系统地描述东北七鳃鳗的早期发育形态特征和生长发育规律。研究结果表明: 东北七鳃鳗的卵裂为全裂类型, 在(18±1)℃水温下, 受精卵经卵裂期、囊胚期、原肠胚期、神经胚期、头凸期、孵出前期以及孵出期, 历时11—12d孵育出仔鱼。初孵仔鱼体重为(0.00032±0.00002) g, 全长为(0.29±0.02) cm。在卵黄囊期内, 仔鱼体重和全长随日龄的增加而增长, 吻长、眼径、眼鳃间距、口笠长、鳃前长、鳃长、头长、体长、尾长和泄殖孔长均存在异速生长现象。初孵仔鱼经过约15d(卵黄囊期)发育成幼鱼, 幼鱼卵黄囊完全吸收, 消化道贯通, 形成肠道, 开始摄食。在幼鱼期, 经5 个月的培育, 幼鱼体重和全长随月龄的增加而增长, 体色逐渐加深, 5月龄幼鱼的体重和全长分别为(0.07±0.01) g和(3.87±0.32) cm。东北七鳃鳗的早期发育研究为七鳃鳗发育生物学积累基础资料, 同时也为七鳃鳗的人工增养殖提供了科学依据, 推进七鳃鳗的模式化进程。

THE EARLY DEVELOPMENT OF LAMPETRA MORII

Lamprey is of considerable model organism to subject of vertebrate evolution and developmental biology. The current study investigated the morphological characteristics and the growth pattern of embryos, yolk-sac larva and ammocoate of Lampetra morii. The results indicated that the cleavage of lamprey zygote was holoblastic cleavage and the embryology had been subdivided into cleavage, blastula, gastrula, neural plate and groove, head protrusion, prehatching and hatching. The newly-hatched larva breaks through the fertilization membrane at 11—12 day-post-fertilization at water temperature of (18±1)℃. The newly-hatched larva had body weight with (0.00032±0.00002) g and total length with (0.29±0.02) cm. During yolk-sac stage, the body weight and total length of larva generally increased over time. The snout length, eye length, postocular length, disc length, prebranchial length, branchial length, head length, trunk length, tail length and cloacal slit length exhibited allometric growth. The ammocoete stage reached when yolk extruded from the anus and the digestive tract completed at 15 day-post-hatch. In 5 months after hatching, the body weight and total length of ammocoete generally increased over time. The melanophores were extensively distributed and increased in ammocoete. The 5-momth old ammocoete had body weight of (0.07±0.01) g and total length of (3.87±0.32) cm. The early development of L. morii is the basic data for artificial culture and developmental biology, which is the basis for the model organism.