Movements and their control mechanism in the alimentary canal of amphibian tadpoles

从比较生理学的角度研究了两栖动物蝌蚪消化道的运动和神经支配。通过透明的腹壁直接观察一些物种的肠道，如装饰蛙，表明在中肠出现下行收缩波，在结肠有节奏地纵向缩短。甲基蓝活体染色显示迷走神经、内脏神经和坐骨尾骨神经丛的一个分支支配着消化道，与青蛙的基本相同。消化道内存在包括vip和NO神经纤维在内的固有神经丛。VIP和5 -羟色胺分别作用于离体的中肠，抑制其节律性收缩。乙酰胆碱增强了它们。这说明蝌蚪肠道的胃肠运动是受自主神经系统控制的。平滑肌细胞免疫组化染色显示，肠壁内的肌肉组织由两层组成，即消化道内任何部位的内圆形和外纵层。中肠纵肌层肌细胞排列不紧密。结肠内圆周层和纵向层的肌肉细胞的排列方式可能导致吸口搅动。

Movements and innervation of the alimentary canal of amphibians tadpoles were studied from the standpoint of comparative physiology.Direct observation of the gut through the transparent abdominal wall in some species such as Rana ornativentris indicated that there occurred descending contraction waves in the midgut and haustral churning plus rhythmic longitudinal shortening in the colon. Vital staining with methyline blue showed that the vagus nerve, splanchnic nerve and a branch of the ischiococcygeal plexus innervated the alimentary canal, which was basically the same as that of frogs. There exists an intrinsic nerve plexus including VIP-and NO nerve fibers in the alimentary canal. VIP and serotonin administered to the isolated midgut of Rana catesbeiana inhibited its rhythmic contractions. Acetylcholine augmented them. These imply that the gastrointestinal movements of the tadpole gut are under the control of autonomic nervous system. Immunohistochemical staining of smooth muscle cells showed that the musculature in the gut wall consisted of two layers : inner circular and outer longitudinal layers in any part of the alimentary canal. Arrangement of the muscle cells in the longitudinal muscle layer of the midgut is not tight. Muscle cells of both circular and longitudinal layers in the colon are arranged in the manner that may cause haustral churning.