Spatial orientation of microtubules in contractile fibroblasts in vivo.

Contracting fibrous tissues from skin wounds in pigs, and scars around silicone implants in humans, contained fibroblasts that had multiple bundles of 60--80 A microfilaments with electron-dense bodies, features typical of contractile fibroblasts both in vivo (myofibroblasts) and in vitro. These in vivo fibroblasts contained many 220 A diameter microtubules, which paralleled plasma membrane in these myofibroblasts strongly suggests a bracing or scaffolding function.