Introduction 
Figure 1. A small section of a typical mammalian cell as seen in the electron microscope. 
Part of the nucleus (N) with its surrounding membrane and nucleolus (Nu ) are shown in 
the upper right; the cytoplasm that occupies the rest of the electron micrograph contains 
several different organelles, including several mitochondria (M), parts of the Golgi com- 
plex (GC), and the rough endoplasmic reticulum (RER). Magnification approximately 
50,000 X. 
Micrograph provided by David D. Sabatini. 
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