[Bone response to unphysiological mechanical stress. A histomorphological study on modelling and remodelling of Martin's transformation zone in the ulna].

In this study the morphological changes in the shape and structure of the ulna were investigated following resection of a mid-shaft segment in the radius. These morphological alterations are called in German "Martin'sche Umbauzone" (MUZ; Martin's transformation zone). Various explanations for the MUZ can be found in the literature; Wolff's law, in particular, offers hints about the development of this phenomenon. The morphological changes in the ulna were investigated by microangiography, polarized light and fluorescence microscopy as well as by micro-radiography. The radius was operated on in 36 mongrel dogs. The development and localization of new bone formation at the endosteal and periosteal envelope of the ulna were studied. The woven bone formation of the envelopes (modelling) and the intracortical remodelling in the distal part of the ulnae were compared with the intact ulnae of the opposite extremities. It is concluded from these morphological alterations that the experimental design chosen provides a valuable, tissue-related model for the investigation of morphogenesis in bones. Further investigations will deal with the correlation between strain and new bone formation.