A critical revaluation of fibre arrangement in the mid-zone (stratum reticulare) of human corium.

Investigation of in situ fixed skin clearly showed distinct arrangement and orientation of collagenous fibre bundles clearly visible only after in situ fixation of whole bodies. Light microscopy seems especially useful to study gross fibre and fibre bundle arrangement, whereas scanning electron microscopy is better suited to study the finer details of fibres and fibre bundles and their arrangement. 2 main directions of fibre bundles were found. The orientation was corresponding to the main mechanical stresses exerted to the skin. No clear start and ending of the fibre bundles could be distinguished. They seem to be arranged in a 3 dimensional texture. Fibres are branching off from one bundle and merge again either with a branch of the same bundle or with a branch of another bundle, in a higher or a lower layer of this 3 dimensional texture. In addition to the 2 main directions of the bundle orientation thin fibres are penetrating the whole texture in various directions. This is especially prominent in regions where vessels, hairbulbs or glands are protruding into the stratum reticulare. A quantitative study of fibre and fibre bundle orientation using semithin sections is under current investigation applying an automatic image analysis system.