This electron micrograph shows the endothelium and the underlying Descemet's membrane of the human cornea. Descemet's membrane is an unusually thick and structurally specialized example of basal lamina, secreted by the adjacent endothelial cells. The collagen of this layer may exhibit an organized array of evenly spaced nodes connected by radiating fibrils to give a lattice-like appearance. Image by T. Kuwabara, Figure 23 from Chapter 1 (The Cell Surface) of 'The Cell, 2nd Ed.' by Don W. Fawcett M.D. A PDF copy of the accompanying chapter is available on the ASCB's BioEDUCATE website.