裸体方格星虫消化道组织学研究

Histological study of the digestive tract in Sipunculus nudus Linnaeus,1766

报道了裸体方格星虫(Sipunculus nudus Linnaeus,1766)消化道各部的形态、组织学结构。结果表明:裸体方格星虫消化道分为口、咽、食道、肠、盲肠、直肠和肛门。肠是消化道的主体,约为躯干长的4倍,通过固肠肌与体壁相连。肠由两个长短不一的肠环组成,肠环下降支和上升支相互盘绕,使肠呈双螺旋状。消化道管壁由黏膜、黏膜下层、肌层和外膜组成,消化道黏膜上皮主要由柱状细胞组成,但消化道的不同部位,柱状细胞的类型和分布不同。除盲肠外,黏膜均向腔面褶成皱襞。肠的各段中均有"V"字型纤毛沟的存在。此外,皱襞的形态、黏膜下层和肌层的厚度等在消化道各部也存在差异。研究表明裸体方格星虫消化道结构与其食性是相适应的。

The form, gross structure and microstructure of the digestive tract in Sipunculus nudus were studied in this paper. The digestive tracts were divided into mouth, pharynx, esophagus, intestine, caecum, rectum and anus. As the most important portion, the intestine was 4 times as long as trunk and was attached to the body wall by fixing muscles. The intestine was composed of two coiled loops, the downward and upward sections of which were coiled around each other, forming a double helix. The wall of digestive tract was consisted of mucosa, submucosa, tunica muscularis and tunica adventitias. The epithelium of the mucosa membrane was mainly composed of columnar cells, whose types and distribution were different at different portions. There was a v-shaped ciliated groove running through the intestine. Meanwhile, the mucosal plica （except for caecum）, submucosa and the thickness of tunica muscularis were different at different parts. These studies showed that the structure of the digestive tract of S. nudus was adapted to its feeding habits.