花背蟾蜍蝌蚪胃的发育形态学观察

应用大体解剖、组织切片和扫描电镜3种形态学方法对花背蟾蜍(Bufo raddei)蝌蚪在生长发育和变态过程中胃的形态结构变化进行了观察。结果显示,在蝌蚪发育24期(即G24)消化道呈简单的管状结构,胃与小肠等区分不明显,胃壁由内层矮柱状黏膜上皮细胞和其外的扁平上皮细胞层构成;直到26期胃略膨大,呈短粗管状,与小肠和食道可明显区分,胃壁内层的黏膜上皮细胞呈高柱状,上皮细胞间出现少量杯状细胞;36期的胃管明显膨大,其壁已具有胃的4层基本组织结构,杯状细胞数量增加,黏膜上皮细胞游离面有细长的微绒毛交织成网状覆盖;42期胃发育呈"C"字形,胃壁具备了消化道典型的4层结构,有胃腺芽出现,黏膜细胞的微绒毛短而直立,仅极少数细胞有长的微绒毛;蝌蚪发育到46期,肠道缩短,胃呈"J"字状,占消化道大部分,胃体中胃腺发达。在临近肝一侧,黏膜上皮细胞的微绒毛较短,胃腺少而小;而在相反一侧,微绒毛较长,胃腺多而大。基于上述结果说明,花背蟾蜍蝌蚪胃在36期已经基本完成了组织结构的分化,在变态发育期间结构和功能得到进一步完善,以适应变态后陆地生活的食性变化。

Developmental Morphology of the Stomach in Siberian Toad (Bufo raddei) Tadpoles

The structural development of stomach was observed in Bufo raddei tadpoles with morphological methods. The results showed that at the stage 24 of Bufo raddei tadpole development, the digestive tract differentiated into simple tubular structure without a distinguished stomach, the wall of stomach was composed of an inner layer of mucosal epithelial cells and an outer layer of squamous epithelium cell. While at stage 26, the stomach was appeared as a fatter and shortter tube compared to other parts of the digestive tract. The stomach wall kept the two layer structure and the mucosal epithelial cells became highly columnar in shape and few goblet-like cells among the epithelial cells. At stage 36, the stomach was obviously swollen. The stomach developed into the general structures with four layers of tissue compounds. Goblet cells appeared in a large number. The free surface of mucosal epithelial cells covered with slender microvilli interwoven into the mesh. At stage 42, the stomach was became to a C-like shape, typical four-layer structure of the stomach was formed