Enteric plexus and interstitial cells of Cajal: interrelationship in the stomach of Podarcis hispanica (Reptilia). An ultrastructural study.

The ultrastructure organization of the stomach enteric plexus was examined in the lizard Podarcis hispanica. The ganglions of the myenteric plexus present a low number of nerve cell bodies with a peculiar nucleus, which occasionally establish direct contacts with cells of the circular muscle layer. Glial cells are smaller than the neurones, and their nucleus is very electron-dense. They surround the axons that constitute the fibres of the myenteric plexus. Four main types of axon profile are described in a morphological consideration of the vesicle population. In the interstice of the circular muscle layer we describe two types of interstitial cells that, due to their ultrastructural characteristics, may be equivalent to the interstitial cells of Cajal which have been described in mammalians. These cells shows parallel distribution to the stomach nerve plexuses, establishing close contacts with them through their long cytoplasmic prolongations. By means of small gap-like unions, they contact both each other and the smooth muscle cells near them. We describe a submucous plexus, where neuronal bodies are scattered among bundles of nervous fibres, some of which are myelinated. A mucous plexus with isolated neurones is located in the lamina propria. Axonal varicosities containing vesicles contact with the cells of the mucous. Interconnected interstitial cells may also be found in this plexus.