Light microscopic immunolocalization of laminin, type IV collagen, nidogen, heparan sulphate proteoglycan and fibronectin in the enteric nervous system of rat and guinea pig.

The localization of the extracellular matrix components laminin, fibronectin and type IV collagen in the enteric nervous system and the surrounding smooth muscle was investigated by immunohistochemical methods, using tissue sections of rat and guinea pig large intestine. None of these molecules were detectable inside the enteric ganglia. In contrast, they were easily demonstrable in association with the basement membrane of satellite cells within sensory and sympathetic ganglia. All of these molecules were, however, present in or nearby the basement membrane that surrounds each enteric ganglion. This agrees with previous ultrastructural observations that, in small mammals, neither basement membranes nor large connective tissue spaces are found inside enteric ganglia. The matrix molecules under study were also detected in the basement membrane of the nearby smooth muscle cells that make up the muscle layer of the gut wall. Fibronectin was frequently observed as a broad staining pattern suggesting its localization in the lamina reticularis rather than in the lamina densa. In addition, nidogen and heparan sulphate proteoglycan were demonstrated in the basement membrane of both enteric ganglia and Schwann cells.