负子蝽的胚胎发育

THE EMBRYONIC DEVELOPMENT OFSPHAERODEMA RUSTICUS

负于蝽Ｓｐｈａｅｒｏｄｅｍａ ｒｕｓｔｉｃｕｓ Ｆａｂｒ．的胚胎发育，早期胚带面积大，呈多叶状，明显区分头、颚、胸、腹叶。发育过程需经历胚带陷入、胚带隆起和胚胎反转三个明显的运动过程。中肠后原基先于前原基形成，并且前、后原基伸展方式不同，使中肠形成不同形态的前、后两部分，两部分的细胞分化亦有差异。神经系统在发育过程中神经节趋于较大程度愈台，腹部的神经节最终愈合为１个复合腹神经节，胸部的神经节也愈合为１个复合胸神经节。本文还总结了胚胎发育时期与卵粒大小的关系，讨论了负于蝽背器官解体的作用。

microscopic investigation on the embryonic development of Spherodema rusticus was conducted and the result indicates that the germ band occupies a large areaon the surface of the yolk in the egg and is polylobed in shape. It is divided intothe cephalic, gnathal, thoracic and abdomenal lobes. In additionic anatrepsis, whichcaused the germ band partly immersing into the yolk, and katatrepsis, the germband from the head to the end of the abdomen had on arched movement just afteranatrepsis, which resulted in the rising back of germ band to the dorsal surface ofyolk and segmentation of the abdomen lobe. In the formation of the midgut, thepost-rudiment was formed prior to the fore-rudiment, and they showed some difference in mode of extension, so that the midgut was differentiated into two parts morphologically-the tubular posterior portion and the elongated ovoid anterior portion.During the development of the nervous system, the ganglia tended to fuse and theabdominal ganglia finally fused into a compound ganglion and so did the thoracicganglia. The relationship between the developmental stage of the embryo and thesize of the egg was noticed and the function of the disintegrating dorsal organ dis-cussed.