LOCALIZATION OF THE LAMININ ALPHA-2 CHAIN IN NORMAL HUMAN SKELETAL-MUSCLE AND PERIPHERAL-NERVE - AN ULTRASTRUCTURAL IMMUNOLABELING STUDY

A particular form of congenital muscular dystrophy is associated with a deficiency of the tissue-specific basement membrane protein laminin alpha 2. A more precise knowledge of the normal distribution and local ization of laminin alpha 2 would be useful in further elucidating the development of this disorder. In this study we used specific electron microscopic techniques, i.e., thin-section fracture labeling and cryou ltramicrotomy in combination with immunogold labeling for laminin alph a 2, to determine its ultrastructural localization in normal human mus cle and peripheral nerve. Both in muscle and in peripheral nerve, lami nin alpha 2 is found to be associated solely with the basal lamina of myofibers and Schwann cells, respectively. Of special interest is the finding that in peripheral nerve, laminin alpha 2 is associated only w ith myelinated and not with unmyelinated nerve fibers.