Differentiation of cholinergic cells in the rat gut during pre- and postnatal life.

In the present work we studied the distribution and number of cholinergic neurons in the rat stomach, ileum and colon starting from prenatal life up to the adult animal. Cryo-cut sections of the three regions were incubated in the presence of the primary choline acetyltransferase (ChAT)-antibody and the immunoreaction was observed under an epifluorescence microscope and photographed. Our results demonstrate that cholinergic neurons are already present during prenatal life in the stomach and ileum, that several steps characterize cholinergic cell differentiation during postnatal life with a consistent delay in the appearance of ChAT-immunoreactivity (IR) in the submucous plexus compared to the myenteric plexus, and that the complete development is accomplished with weaning. In the colon the total number of ChAT-IR cells does not change from the suckling period to adulthood; a significantly larger number of ChAT-IR cells is found in the ileum of 5-day-old rats than in that of adult rats.