NEW HYPOTHESIS OF CONTACT GUIDANCE IN TISSUE-CELLS

The reaction of chick heart fibroblasts to the curvature of cylindrical substrata was assessed using a measure based on the ratio of nuclear dimensions along and across the axis of the substratum. A hypothesis of contact guidance was proposed which states that the shape of the substratum imposes mechanical restrictions on the formation of certain linear bundles of microfilaments which are involved in cell locomotion. This hypothesis was used to predict fibroblast behavior on prism-shaped substrata and the prediction was confirmed by experiment. A transmission electron microscope examination of whole spread chick heart fibroblasts at 80 kV and 2 MV revealed discontinuities in the microfilament bundle system which coincided with a discontinuity in the shape of the substratum.