Comparison of NOS distribution in myenteric plexus of various segments of gastrointestinal tract of the mandarin vole,Microtus mandarinus

Objective: To interpret the adaptive regulating mechanism of the Microtus mandarinus digestive tract to its life history. Methods: The distribution of nitric oxide synthase (NOS)-containing neurons in the gastrointestinal tract of the Microtus mandarinus was studied with NADPH-diaphorase histochemistry. Results: 1) The shape and size of the NOS positive neurons were varied. 2) The ganglia and positive nerve fibers formed complex meshwork, and there existed beads-shaped and U-shaped structure. 3) There was a significant regional variation along the gastrointestinal axis in the density of NOS positive neurons: the highest was in the colon, the second was in the ileum, and the density in the stomach and the cecum was lower than that in the ileum, but higher than that in the duodenum and the jejunum. Conclusion: The feature of NOS positive neuron distribution in myenteric plexus of various segments of the Microtus mandarinus digestive tract probably adapts to its feeding habit and physiological function of digest.