Morphological changes of the myenteric plexus neurons in the bullfrog (Rana catesbeiana) duodenum during metamorphosis.
Myenteric plexus neurons of the duodenum in the bullfrog Rana catesbeiana were examined during metamorphosis by the Gros-Bielschowsky silver impregnation method and electron microscopy. Larval type neurons with slender and curved cell soma were recognized in the duodenum of the premetamorphic tadpole. They degenerate and decrease in number during early metamorphic climax through shrinkage of the cell soma and autolysis of the cytoplasm. These larval type neurons reduce to debris and then disappear. Two new cell types (adult type neurons) subsequently appear. These new neurons develop and increase in number during late climax and after metamorphosis. Those that appear first are large type A neurons each with a prominent axon and they stain darkly with silver. They enlarge during late stages. Subsequently small type B neurons appear which stain weakly with silver. They increase the number of their dendrites, change their shape, but enlarge only slightly during late development. In summary, therefore, it is concluded that during metamorphosis, the larval myenteric plexus neurons in the bullfrog duodenum are replaced by two new populations of adult neurons.
Torihashi
S
S
Department of Anatomy, Yamanashi Medical College, Japan.
D000818:Animals; D002452:Cell Count; D004386:Duodenum / Q000254:growth & development / Q000294:innervation*; D008675:Metamorphosis, Biological / Q000502:physiology*; D008854:Microscopy, Electron; D009197:Myenteric Plexus / Q000254:growth & development*; D009410:Nerve Degeneration / Q000502:physiology; D009474:Neurons / Q000648:ultrastructure*; D011892:Rana catesbeiana / Q000254:growth & development*; D012834:Silver
D012834:Silver