Rapid extension of microvilli on the surface of a peritoneal macrophage, induced by treatment with a metabolic inhibitor, sodium azide, after 20 minutes at 22° C. Microvilli on neighboring lymphocytes in the upper left and right corners do not respond to this treatment. Image by Emma Shelton, Figure 36 from Chapter 2 (Specializations Of The Free 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.