IMMUNOCYTOCHEMICAL LOCALIZATION OF DESMIN IN HUMAN FETAL SKELETAL-MUSCLE

The distribution of desmin filaments in the skeletal and cardiac muscl es of experimental animals and cultured cells have been extensively st udied. The purpose of this report is to identify the distribution of d esmin filaments in vivo in human fetal skeletal muscle. Using 10 nm go ld-particle-labeling immunoelectron microscopy, desmin intermediate fi laments were localized in skeletal muscles of 12, 20 and 29-week-old h uman fetuses. A number of desmin filaments were closely associated wit h the nascent nonstriated myofibrils. Nascent myofibrils were distribu ted in the subsarcolemmal space at all three developmental stages. Des min, accompanying the nascent myofibrils, was most abundant after 12 w eeks of gestation. An irregular network of desmin filaments was conspi cuous in the subsarcolemmal space after 20 weeks of gestation. Desmin filaments penetrated the myofibrils and the Z-discs after 29 weeks of gestation. The developmental change in fine structural localization of desmin between 12, 20 and 29 weeks of gestation in human fetuses indi cated that desmin filaments were involved in myofibril assembly in the subsarcolemmal space, and also in myofibrillogenesis in the inner spa ce of the myofibrils.