Smooth muscle of gut wall. Transmission electron micrograph (TEM) of a section through the outermost wall of the intestine, showing smooth muscle cells in longitudinal section (lower left) and cross-section (upper right), and nerve tissue in between (diagonal, centre). The different orientation of muscle allows lengthwise and transverse contraction of the gut tube. The nerve tissue forms an extensive neural network within the smooth muscle layers of the gut and is known as the myenteric (or Auerbach's) plexus, part of the enteric nervous system (ENS). It plays an essential role in coordinating contraction. Magnification: x11,000, when printed 10 centimetres wide.