Laminin immunoreactivity in enteric ganglia of the chick embryo

The localization and time of appearance of laminin in the duodenum of the chick embryo were studied with an anti-laminin polyclonal antibody and immunofluorescence. Laminin immunoreactivity was observed in the basement membranes of the mesothelium, mucosal epithelium, muscle cells and in the adventitia and basal surface of the endothelium in blood vessels. In addition, laminin immunostaining was detected over the contour of myenteric ganglia from embryonic day 7 and inside these ganglia from embryonic day 13. In colocalization experiments, laminin immunoreactivity occurred outside tubulin immunoreactive neuronal cell bodies, thus indicating that it resides in glial cells or in extracellular spaces. In addition connecting strands of the myenteric plexus and intramuscular nerves expressed laminin immunoreactivity. Similar observations were made in the proventriculus, gizzard, ileum and rectum of chick embryos, and in the duodenum and rectum of quail embryos. In the ganglion of Remak, laminin immunofluorescence was detected in the collagenous sheath that surrounds the ganglion and inside the ganglion, where it outlines neuronal cell bodies. Laminin immunoreactivity within the myenteric ganglia during the 3rd week in ovo, appears to be characteristic of the avian species examined, since it was not observed in the rat and mouse intestine at equivalent developmental stages. Immunocytochemical experiments at the electron-microscope level confirmed that structures with laminin or laminin-like immunoreactivity occur both around and inside myenteric ganglia. It is suggested that laminin, or an immunologically similar molecule, may play a role in the development and maturation of avian enteric ganglia.