隆线溞[Daphnia(Ctenodaphnia)carinata]卵鞍的超微结构

ULTRASTRUCTURAL STUDIES ON THE EPHIPPIUM OF DAPHNIA (CTENODAPHNIA) CARINATA (CRUSTACEA:CLADOCERA)

在不利的环境条件下,枝角类中有一部分种类可以形成卵鞍(ephippium),内含休眠卵。本文应用扫描电镜和透射电镜对隆线溞的卵鞍进行了超微结构的研究。研究表明:卵鞍外面大部分略呈浅的蜂窝状,内面则排布着多数卵石状小突起。卵鞍分为内外两层,两层的超微结构截然不同;各层又可分为三小层。

The ultrastructure of the ephippium of Daphnia (Ctenodaphnia) carinata was studied with scanning and transmission electron microscopy (SEM & TEM).The ephippium is composed of a external shell and a inner shell. There are two row; of small spines and an elastic rope in the dorsal margin of external shell which can close the ephippium. Outer surface of the external shell is covered by recesses, but near the dorsum it shows hexagonal scaly structure. The inner surface of the inner shell is covered by cobble-like tubercles. Inner surface of the external shell and outer surface of the inner shell consist of crust fibre in different arrangement. In ultrathin section, the walls of the ephippium are formed by several layers with varying thickness. The wall of the external shell consist of three layers. The exterior is the thin cuticle. The second layer, the fibre layer, is composed of longitudinal and transverse protein-chitin fibre. The inner layer is a matrix with a number of pore and irregular lattice region. The wall of the inner shell is also divided into an outer, fibre region, a middle material-dense layer and an inner cuticle layer. The cobble-like tubercles observed in SEM are commonly formed by parts of two innermost layers of the inner shell.