日本七鳃鳗消化系统显微与超微结构

采用光镜和电镜技术研究日本七鳃鳗(Lampetra japonica)消化系统的组织结构。结果显示,日本七鳃鳗食道褶皱处黏膜上皮为复层立方上皮,褶皱基部为变移上皮。由于生活方式的特化,其胃退化。前肠、中肠和后肠黏膜上皮均为单层柱状上皮,其中并未发现杯状细胞,有肠腺,肠上皮有密集的纤毛,上皮细胞内各种细胞器均较丰富,肌纤维斜行。肝小叶界限不清,肝内无胆管。内分泌性胰由若干个大小不等和形状不定的细胞团组成。口腔腺上皮细胞高柱状,游离端充满酶原颗粒和微管泡系,细胞间有分泌小管。日本七鳃鳗消化器官的组织结构特点与其特殊的取食方式和进化地位密切相关。

Microstructure and Ultrastructure of the Digestive System in Lamprey Lampetra japonica

The histological structure of digestive tract of Lampetra japonica was studied by light and electronic microscopy.Stratified cuboidal epithelium in the fold of oesophagus mucosa and transitional epithelium in the bottom of the fold were observed.Because of the life style specialization L.japonica lost its stomach.The fore-,mid-and hind-intestines were characterized by single-layered columnar epithelium,and there were numerous dense cilia and abundant cell organelles in the epithelial cells.The muscle bifers distributed obliquely.The lobules were not distinctly observed and there was no bile duct in the liver.The endocrine pancreas consisted of cell mass in different sizes and various shapes.The secretory epithelium of the buccal glands consisted of high columnar cells which contained numerous granules and tubular vesicles,some of which were zymogen-like.There were many tubular vesicular systems among these cells.In summary,there is a close correlation between the histology structure characteristic of digestive system and particular feeding behavior in this species.