不同发育期的牛蛙蝌蚪消化道组织学观察

取不同发育期牛蛙蝌蚪通过解剖和切片观察可以看出，牛蛙蝌蚪消化道组织由不发达慢慢发育完全，表现为浆膜层逐渐明显，肌肉层由不成层平滑肌细胞逐渐发育成层、增厚；粘膜层、食道粘膜上皮由单层柱状上皮向复层扁平上皮演变，固有层在后期出现食道腺，胃肠道粘膜上皮为单层柱状上皮，各级消化道结构在变态时变化最大。

Observation of Digestive Tract Histology of Bullfrog Tadpole at Different Development Stages

Bullfrog(Rana catusbeiana )tadpoles at different development stages were observed through dissection and slice.The results indicated that the digestive tract structure of the bullfrog tadpoles developed slowly from hypoplasia.The serosa gradually became clearer.Muscle layer gradually developed into membrane and thickened from unmembrane smooth muscle cells.The upper epidermis of the esophagus mucosa developed into complex membrane flat upper epidermis from single membrane columnar epidermis.The intrinsic membrane appeared esophagus line during later stages.Upper epidermis of stomach and intestines mucosa were single membrane and columnar.The structure change of different sections of the digestive tract was maximum during metamorphosis.