EM 236 Smooth Muscle Cell

Smooth Muscle Cell

Smooth muscle contains the same contractile proteins (myosin and actin) as skeletal and cardiac muscle. However, the less organized array of contractile proteins does not produce striations.

This experiment examined the change in morphology of isolated smooth muscle cells induced to contract by electrical stimulation.

• Light Microscopy (yellow)
  • Relaxed cell - long, narrow cell
  • Contracted cell - short, wider cell with an irregular surface
• Electron Microscopy (blue)
  • Relaxed cell - long, narrow cell with a smooth surface
  • Contracted cell - short, wider cell with an irregular surface with bulbous evaginations

The dense bodies are connected by myosin-actin filaments through th cytoplasm, which cause the smooth muscle cell to contract.

Scalebar: top, 25 µm; bottom, 5 µm