[Role of the extracellular matrix in X-chromosome-linked muscular dystrophy: immunohistochemical study]

To study the role of the extracellular matrix in the pathogenesis of the X-linked muscular dystrophy.

Muscle specimens from 8 normal controls with ages ranging from 4 to 14 years of age and those of 14 X-linked muscular dystrophy patients were studied by means of polyclonal antibodies able to recognize extracellular matrix molecules. The findings of each of the controls and patients were evaluated systematically using a semiquantitative morphological method. On the other hand, with the help of an automatic interactive image analyzer, the following structures were measured: a) area occupied by the perimysium; b) area of the endomysium, and c) transverse fibre area.

The deposition of the extracellular matrix components of patients with X-linked muscular dystrophy is a selective phenomenon which is mostly related to groups of fibers undergoing necrosis-regeneration. X-linked muscular dystrophy patients have an heterogeneous clinical and pathological picture. At one end of the spectrum there are patients with the most severe phenotype, in which reduction of fiber size, early deposition of connective tissue and distortion of the capillary bed are the most conspicuous pathological changes. At the other end muscle fiber hypertrophy and splitting, lesser connective tissue deposition and a milder clinical course predominate. Selective deposition of extracellular matrix components occurs at each point of the spectrum. The distribution of the extracellular matrix components does not appear to accomplish a substitutive function designed to replace the loss of number or volume of the muscle fibers.