VIP-, enkephalin-, substance P- and somatostatin-like immunoreactivity in neurons intrinsic to the intestine: immunohistochemical evidence from organotypic tissue cultures.

Small intestine from 18-day fetal mice grown for 3 weeks in organotypic tissue culture was found to contain numerous VIP, enkephalin, substance P and some somatostatin immunoreactive nerve fibers. Since these cultures should be devoid of all afferent or other extrinsic neuronal inputs, it is concluded that there are VIP, enkephalin, substance P and somatostatin containing neurons intrinsic to the intestinal wall. However, all 4 peptides may also be present in neurons originating outside the gastrointestinal tract as well as in the intrinsic neurons.