Studies on the intrinsic nervous system of the wild rodent Calomys callosus digestive tract. II: The submucous plexus

Abstract

The submucous plexus of the normal small and large intestine of Calomys callosus was studied by NADH and AChE histochemical techniques and by transmission and scanning electron microscopy.The plexus contains ( x _ ± SD) 7,488 ± 293 neurons/cm 2 in the duodenum, 5,611 ± 836 in the jejunum, 2,741 ± 360 in the ileum, 3,067 ± 179 in the cecum, and 3,817 ± 256 in the proximal colon. No ganglia or nerve cell bodies were seen in the esophagus, stomach, distal colon or rectum. The neurons are pear-shaped with a round or oval nucleus and the neuronal cell profile areas were larger in the large intestine than in the small intestine. Most of the neurons display intense AChE activity in the cytoplasm. AChE-positive nerve fibers are present in a primary meshwork of large nerve bundles and in a secondary meshwork of finer nerve bundles. At the ultrastructural level, the ganglia are irregular in shape and covered with fibroblastlike cells. The nucleoplasm of the neurons is finely granular with a few condensations of chromatin attached to the nuclear envelope. In the neuropil numerous varicosities filled with vesicles of different size and electron densities are seen. The pre-and post-synaptic membrane thickenings are asymmetric. Characteristic glial cells with oval nuclei and few organelles are numerous. These data provide a detailed description of this submucosal meshwork.

Organisation of Autonomic Nervous Structures in the Small Intestine of Chinchilla (Chinchilla laniger, Molina)

“…The 2nd‐ and 3rd‐order bundles of fibres formed connections with the internal submucosal plexus (Balemba et al., ). Morphological and quantitative analysis of neurones in the submucosal plexus carried out in Calomys callosus (Souza et al., ) showed that the average number of ganglion neurones varied in different sections of the intestine – 293/cm 2 in the duodenum, 836/cm 2 in the jejune and 2741/cm 2 in the ileum – and the cells exhibited AChE positive activity, which was also confirmed by the observations in chinchillas.…”

Organization of the innervation of the oesophagus and stomach in chinchilla (Chinchilla laniger, Molina)

“…Moreover, the adrenergic fibres came into contact with blood vessels and mucosal glands [6]. Striated muscles build the wall of the oesophagus in wild mouse (Calomys callosus) and hamster, and in these species only nerve fibres formed the submucosal plexus [17,22]. In cat, analysis of the density of ganglionic neurons in the submucosal plexus with mixed muscle type revealed the presence of only nerve fibres, and in opossum there was an increase in the number of neurons in the caudal direction [23].…”