Cells from peritoneal cavity exudate of the mouse, exposed to sodium azide at 22°C for 22 minutes. The macrophage in the field of view has extended long microvilli, showing a rapid response to changes in metabolic and environmental conditions. Image by Emma Shelton, Figure 35 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.