Microanatomy of the dermis in relation to relaxed skin tension lines and Langer's lines.

The microanatomy of the dermis was studied by optical and scanning electron microscopy in order to visualize the relationship between orientation of fibers and skin tension lines. In the reticular dermis of the normal adult human, skin tension lines have an anatomical counterpart consisting of a preferential parallel orientation and a straightening of thin collagen bundles and elastic fibers. This was observed only when mechanical tensions normally present in the skin were preserved during the processing of the samples, but was not observed in those that had retracted during biopsy. A comparative study of the fetal skin of calves, where relaxed skin tension lines were absent, offered further evidence that the presence of tension lines in the skin depends on the interrelationship between elastic fibers and collagen fibers, as well as on the anchorage of collagen bundles one upon another.