NEURAL CELL-ADHESION MOLECULE (NCAM) EXPRESSION IN NERVES AND MUSCLE OF DEVELOPING HUMAN LARGE-BOWEL

Most studies of neural cell adhesion molecule (NCAM) in human musculat ure are devoted to either developing or adult skeletal and cardiac mus cle. The aim of this study was to determine the pattern of NCAM expres sion in the intestinal musculature of the developing human large bowel . In specimens of large bowel from foetuses (gestational age 8-20 week s), we examined the immunohistochemical localisation of NCAM in parall el to those of cw-smooth muscle actin and desmin. Within the developin g neural complex, NCAM was expressed at all stages investigated. In in testinal muscle at 8 weeks, immunoreactivity for all antisera was rest ricted to the muscularis propria. The differentiating muscularis mucos ae was demonstrated first at 15 weeks by immunostaining for ct-smooth muscle actin, and this expression was followed by that of NCAM and des min at 17 and 19 weeks, respectively. At 20 weeks, NCAM immunoreactivi ty in the external muscle was intense at the inner border of the circu lar muscle, with its concentration decreasing towards the outer margin of the muscular wall, whereas ol-smooth muscle actin and desmin were uniformly distributed in all muscle layers. NCAM is expressed by nerve s and muscle of developing human large intestine. Its appearance follo ws a predetermined pattern, which implies its relevance to the differe ntiation of intestinal muscle layers.