The effects of magnesium deficiency on the host response to intramuscular bone matric implanted in the rat.

HCl-demineralized mid-diaphyseal allogeneic segments of tibia were implanted in the lumbar muscles of rats fed either a magnesium-deficient or a magnesium-supplemented diet for one week prior to implantation and for three weeks thereafter. Histological studies, histochemical mucopolysaccharide determinations, tests for protease content of undemineralized bone tissue, and microradiography showed that in the normal hosts mostly trabecular bone grew into the heterotopic site, whereas in the deficient rats a large fibrous covering formed about the implant and in many instances cartilage was present in multiple locations under the fibrous coat. In some instances cartilage wedges, not preceded by multinucleated giant cells (matrixclasts), invaded the implant. This fibrocartilaginous response to an exogenous inductor resembled the modified growth pattern of bone recently reported in magnesium-deficient rats.