Upper panel shows a transmission electron micrograph featuring the nuclear envelope with the nuclear lamina seen here as a uniform layer between the inner nuclear membrane and more darkly staining blocks of heterochromatin in this human skin cell. The lamina appears to be discontinuous over the nuclear pore. Lower panel shows a thinner and more darkly staining lamina in a rodent Leydig cell. Figures 157 (upper, courtesy of George Szabo) and 158 from Chapter 4 (Nucleus) 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.