Spatial pattern analysis of nitrergic neurons in the developing myenteric plexus of the human fetal intestine

Enteric nervous system precursors derived from the neural crest migrate along defined pathways to colonize the bowel. The individual cells in different environments experience different growth, differentiation, and survival conditions. Hence, the spatial distribution of the neurons is determinant with regard to functional maturation. The question arises as to whether the distribution is random or nonrandom.

Nitrergic cells were visualized by means of nicotinamide adenine dinucleotide phosphate diaphorase histochemistry. Stained specimens were photographed, and the borders of the myenteric plexus and the nuclei of the nitrergic neurons were digitalized. Plexus Pattern Analysis software was used to count the nuclei of nitrergic neurons, calculate the proportions of the areas covered by the plexus and the gut wall, and perform randomization analyses.

The distribution pattern of the nitrergic neurons changed markedly between weeks 14 and 22 of gestation. The nitrergic neurons were randomly distributed at week 14 but were aggregated in the plexus and within the individual ganglia at week 19. The dynamics of these changes exhibited regional differences.

The results suggest that, in addition to the gut wall and the plexus, other intraganglionic constituents may contribute to the aggregation of nitrergic cells and such examinations should be extended to other cell types in the future.