IDENTIFICATION OF NEURONS THAT EXPRESS STEM-CELL FACTOR IN THE MOUSE SMALL-INTESTINE

Background & Aims: Enteric neurons in the murine intestine express ste m cell factor (SCF), which may provide an important signal in the deve lopment of the interstitial cells of Cajal (ICC). Our aim was to ident ify the subpopulation(s) of myenteric neurons that express SCF, Method s: Myenteric plexus preparations from postnatal SCF-lacZ mice were pro cessed for beta-galactosidase histochemistry followed by immunohistoch emistry. Results: Approximately 60% of the nitric oxide synthase-immun oreactive neurons, which projected to myenteric ganglia and to circula r muscle, expressed SCF, and more than 80% of the calbindin-immunoreac tive neurons, which projected exclusively to myenteric ganglia, expres sed SCF. A small subpopulation of calretinin-immunoreactive neurons ex pressed SCF transiently. Many of the remainder of SCF-expressing neuro ns were choline acetyltransferase immunoreactive, but their projection s are unknown. Conclusions: SCF-expressing neurons that project within the myenteric plexus may be an important source of SCF for the develo pment of Kit-expressing ICC at this level. The only possible neuronal source of SCF for the ICC of the deep muscular plexus is a subpopulati on of nitric oxide synthase-immunoreactive neurons.