Histochemical loacalization and analysis of the cholinergic and nitrergic neurons in the chicken ileum were investigated by staining with acetylcholine esterases (AChE) and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d), respectively. AChE and NADPH-d activity was demonstrated in neuronal cell bodies and nerve fibres in the chicken ileum. The positive neurons showed irregular or polygonal shape and were mainly present sporadic or clumped in the myenteric and submucosal plexus. The positive nerve fibres frequently surrounded the ileac blood vessels. They were abundantly present in myenteric and submucosal plexus of the ileum forming a network. Some positive nerve fibres traversed the submucosa into the lamina propria mucosae. Fine nerve fibres were found to penetrate into intestinal villi underneath the epithelium. Extensive networks of more intensely staining AChE positive nerve fibers were present in the mucosa as compared to that of NADPH-d positive fibers. Ganglia density of submucosal plexus was markly biger than that of myenteric plexus, whereas neurons per ganglion and the number of neurons per mm² and the size of neurons of submucosal plexus were shorter than that of myenteric plexus. In addition, the number of AChE positive neurons and nerve fibres was more than that of NADPH-d positive neurons and nerve fibres. We concluded that the chicken ileum is characterized by abundance of nerve structures which may play a significant functional role in ileum of the chicken.

Key words: AChE, Chicken, Ileum, NADPH-d, Neurons