Peptide-containing neurons in explant cultures of guinea-pig myenteric plexus during development in vitro: gross morphology and growth patterns.

The gross morphology and growth patterns of substance P, enkephalin-, somatostatin- and vasoactive intestinal peptide-immunoreactive neurons have been studied in explant cultures of the myenteric plexus taken from beneath the newborn guinea-pig taenia coli, grown for up to 4 weeks in vitro. Substance P- and enkephalin-immunoreactive neurons were more abundant than somatostatin- and vasoactive intestinal peptide-immunoreactive neurons. The peptide-containing neuronal cell bodies were clearly visible in culture and exhibited characteristic gross morphologies similar to those described in situ, although some overlap of shape between populations containing different peptides was seen. All four types of peptide-containing fibres were found in the outgrowth and central areas of the cultures. In the case of substance P and somatostatin, the density and pattern of labelling in the central, neuronal area of the cultures resembled that previously seen in the myenteric plexus of the newborn guinea-pig caecum in situ, while the density of the enkephalin-immunoreactive fibres was greater, and that of the vasoactive intestinal peptide-immunoreactive fibres less than that seen in situ. These observations suggest that subpopulations of myenteric neurons containing different peptides may be differentially affected by the culture environment. Possible contributory factors are discussed.