光裸方格星虫消化道的形态和组织学观察

Morphological and histological observations on digestive tract of Sipunculus nudus

中文关键词: 光裸方格星虫  消化道  形态学  组织学

英文关键词: Sipunculus nudus  Digestive tract  Morphology  Histology

中文摘要:

      对光裸方格星虫Sipunculus nudus消化道各部分结构进行了形态学和组织学观察，表明消化道由口、咽、食道、肠、直肠和肛门组成。口四周着生有触手形成口盘，咽短与口分界不明显，食道随翻吻伸缩，肠道极长，通过3个回折及螺旋缠绕成肠索，直肠上附有直肠盲囊。消化道管壁由内向外分为黏膜层、黏膜下层和外膜，没有连续的肌肉层，只有数量不等的肌纤维在黏膜下层。黏膜上皮主要由柱状细胞组成。除肠外，消化道上皮细胞均有发达的纤毛。消化道各部位的褶皱形态、黏膜下层和肌纤维数量都具有差异。

英文摘要:

      Morphological and histological observations of the digestive tract in Sipunculus nudus were conducted with light microscopy. The digestive tract consists of mouth, pharynx, esophagus, intestine, rectum and anus. The mouth is surrounded by tentacles to form a mouth tray, and the pharynx is short and has no clear borderline with the mouth. The esophagus can draw back and forth. The intestine is very long and reverses three times to form a spiral. Caecum is attached to rectum. The wall of digestive tract is composed of mucosa, submucosa and adventitia, having no continuous muscle layer, only with numbers of muscle fibers in the submucosa. The epithelium of the mucosa membrane in digestive tract is mainly composed of columnar cells with developed microvilli except for intestine. The form of plica, the submucosa and the quantity of muscle fibers are also different among various parts of the digestive tract.