Contraction of Single Smooth Muscle Cells from Bufo marinus Stomach

MANY aspects of vertebrate smooth muscle function cannot be studied adequately in the whole animal or in vitro because the collagen net surrounding individual cells distorts force-time relationships 1 . Electron microscopy of smooth muscle tissues has provided some data on structural changes during contraction 2,3 , but the difficulty in obtaining sections in the correct plane and lack of a suitable method for viewing contractile elements in three dimensions has impeded progress. Lowy and Small 4 , using a weight to stretch guinea-pig taenia coli during fixation and dehydration, observed a ribbon-like arrangement of myosin filaments but could not study contracted cells prepared the same way.