The distribution of different subpopulations of enteric neurons in the developing enteric nervous system has been extensively examined in various animals, but up to date, there is no reference found regarding with the normal cholinergic neuronal density and morphology in the submucosal plexus of the developing chicken. In the present study, the fresh specimens were collected at day old, 5, 10, 20, and 40 days chickens respectively, for the whole-mount preparations of the submucosal plexus of chicken ileum. Acetylcholinesterase (AChE) histochemistry was performed. The morphology of the network, cytoplasmic area, the density of the ganglia, and number of the ganglion cells per ganglia was measured. Our results reported that the positively stained neurons have various morphologies and staining intensity. They formed a clear network by ganglia and nerve fibers. The number of ganglia per unit area decreased with age, however the size of positive neurons increased, as the size, in 40 day old group was 3 times than that of the day old group. Change the number of positive neurons per ganglia was dynamic, but the tendency was increased from 10-days old to adult chickens. It was concluded that the significant developmental changes occur in postnatal life of chicken ileal submucosal plexus. The changes of the cholinergic neuronal subpopulation are similar than it has been found in the nitrergic subpopulation in different animal models.

Key words: Acetylcholinesterase (AChE) histochemistry, Chicken, Development, Enteric nervous system (ENS), Submucosal plexus