Studies on the embryonic development of sterlet

The embryonic development characteristics of starlet(Acipenser ruthenus Linnaeus) were studied,under the water temperature 18±1℃.The results showed that the fully mature eggs were spherical,black,opacity,sticky,and 2.2～2.8 mm in diameter.it took 110 h from fertilization to hatching-out with the average acumulative temperature of 2023～2308 ℃·h.The cleavage pattern of starlet were peculiar radial holoblastic cleavage.The cells of animal pole had two-thirds covered the whole embryon at midgastrula stage.The heart were C type at stage of heart beating.The optic capsule had had pigment when the tail end approached heart.The embryonic development process could be divided into 7 stages,including fertilized egg stage,cell division stage,blastula stage,gastrula stage,neurula stage,organ formation stage and hatching stage.They contained thirty-four developing phases,whose characteristics were described in detail.In addition,the embryonic development characteristics of sterlet and other sturgeons were comparatively analysed in this paper.