Ontogenesis of the myenteric plexus in the cat gastro-intestinal sphincters. I. Development of the neuronal perikarya and dendrites.
The pre- and postnatal development of the myenteric nerve perikarya and processes in gastro-intestinal sphincters was studied by means of light and electron microscopes. In the early fetal period, when migrate neuroblats were still seen, the myenteric ganglia were not formed. A peculiarity of each period of development was the presence of relative proportions of immature, transitional and mature nerve cells. With the progress of development the number of the immature neurons decreased, although single undifferentiated neurons were observed in adult cats. Multi-, bi- and pseudounipolar cells were distinguished in the late fetal period. On the electron microscope different myenteric neuronal types were differentiated in this period too. At birth and during the first postnatal weeks the impregnation showed an intensive dendritic branching and the Dogiel nerve types were well distinguished. To that corresponded a great variety in the fine structure of the dendrites. The nerve perikarya displayed a larger size and a richer content of organelles. Special attention was directed to the differences in the impregnation and fine structural features of the myenteric perikarya and dendrites the sphincters studied during the development.
D000375:Aging; D000818:Animals; D002415:Cats; D003712:Dendrites / Q000502:physiology* / Q000648:ultrastructure; D004064:Digestive System / Q000294:innervation*; D005260:Female; D005865:Gestational Age; D009197:Myenteric Plexus / Q000166:cytology / Q000196:embryology / Q000254:growth & development*; D009474:Neurons / Q000502:physiology*; D011247:Pregnancy