Figure 189 from Chapter 5 (Endoplasmic Reticulum) of 'The Cell, 2nd Ed.' by Don W. Fawcett M.D. A High magnification electron micrograph of smooth endoplasmic reticulum from an adrenal cortical cell shows the tubules branch and anastomose frequently, and vary in diameter, to produce a compact 3-dimensional reticulum. Micrograph by Daniel Friend. A PDF copy of the accompanying chapter is available on the ASCB's BioEDUCATE website.