IMMUNOLOCALIZATION OF THROMBOSPONDIN-1 IN HUMAN, BOVINE AND RABBIT CORNEA

Light- and electron-microscopic immunohistochemical techniques were us ed to investigate the distribution of the matricellular protein thromb ospondin 1 in normal human, bovine and rabbit cornea. Light-microscopi c immunoreactivity for thrombospondin 1 was observed in the epithelial basement membrane, posterior Descemet's membrane and endothelium of h uman and bovine cornea. The bulk of the stroma, the stromal cells (ker atocytes) and the anterior part of Descemet's membrane in human and bo vine cornea were devoid of detectable thrombospondin 1 and the protein could not be demonstrated in any of the layers of the rabbit cornea. Electron-microscopic immunogold studies of human and bovine cornea rev ealed that thrombospondin 1 labelling of corneal endothelial (and basa l epithelial) cells included focal deposits at cell membranes. It is p ostulated that thrombospondin 1 regulates interactions between cells a nd their basement membrane, and perhaps cell-to-cell interactions, in the normal human and bovine corneal endothelium and basal epithelium.