A comparative immunohistochemical study of human corneotrabecular tissue.

Using in situ immunohistochemical techniques and a broad panel of antibodies directed against intermediate filament proteins, vascular endothelial markers, neuroectodermal/neuroendocrine markers, and monoclonal antibodies raised against human corneal endothelial cells (HCECs), a comparative phenotypical analysis was performed on HCECs, keratocytes, trabecular cells, and cells lining the canal of Schlemm. The coexpression of cytokeratins and neurofilaments by HCECs argues in favor of a neuroectodermal origin, which is further supported by the fact that they stain positive for neuron-specific enolase (NSE) and that they express neural cell adhesion molecules (N-CAM) at their surface. The expression of NSE and N-CAM also applies to the trabecular cells. The cells lining the canal of Schlemm were found to share many immunophenotypical features with vascular endothelial cells (i.e., factor-VIII-related antigen and BMA-120), rather than with HCECs. This was further supported by the reactivity of two monoclonal antibodies (i.e., 9.3 E and 5.52 H) that were raised against HCECs, and which labelled vascular endothelium and cells lining Schlemm's canal.