The innervation of the gastrointestinal tract of a chelonian reptile, Pseudemys scripta elegans. I. Structure and topography of the enteric nerve plexuses using neuron-specific enolase immunohistochemistry.

The general morphological features of the intramural enteric nervous system of a chelonian species, i.e. the red-eared turtle, Pseudemys scripta elegans, has been studied in whole-mounts and cryosections by means of neuron-specific enolase immunohistochemistry. A clear visualization of both neuronal cell bodies and nerve fibres allows the recognition of a myenteric plexus as well as a submucous plexus in several gut regions, namely the stomach, midgut and hindgut. The highest innervation density was found in the midgut portion. In contrast to other lower vertebrates, such as amphibians and other reptilian groups, the present study clearly demonstrates the occurrence of neuronal cell bodies in the submucous plexus of all regions investigated. The neurons stained for neuron-specific enolase harboured smooth-contoured perikarya from which one or more processes emerge, as demonstrated for the mammalian enteric nervous system.