Nerve. Light micrograph (LM) of a 1 micron section through part of a nerve bundle from the sciatic nerve. Myelin sheaths (dark brown circles) can be seen surrounding the axons (light brown dots). Perineurium (connective tissue, (yellow) surrounds the nerve bundle. Adipose (fat) cells (black) surround the nerve bundle. Magnification: x200 when printed at 10 centimetres wide.