Immunocytochemical colocalization of desmin and vimentin in human fetal skeletal muscle cells.
BACKGROUND
Desmin and vimentin are the major intermediate filaments in muscle. They have been extensively studied in animal experiments. This study is the first to identify the distribution and to analyse the correlation of desmin and vimentin in human fetal skeletal muscle. Vimentin might be replaced by or transformed into desmin during myogenesis in chick embryo, although the precise process remains to be elucidated. The aim of this report is to evaluate the ratio of desmin to vimentin in human fetal muscle.


METHODS
By double-labeling immunoelectron microscopy, desmin and vimentin intermediate filaments were localized in developing skeletal muscles of 20-29-week-old human fetuses. The ratio of desmin and vimentin was analyzed statistically.


RESULTS
Two sizes of colloidal gold particles, 5 nm (vimentin) and 10 nm (desmin), were distributed along the intermediate filaments. The commonest distance between gold particles was approximately 40-50 nm. Desmin and vimentin labeled with gold particles were arranged very close together in the same intermediate filament. The ratio of vimentin to desmin varied but the amount of vimentin decreased progressively from the undifferentiated myoblast to the differentiated myocytes. As the fetuses developed, desmin increased and vimentin decreased. Desmin and vimentin intermediate filaments were identified in the intermyofibrils of differentiated myocytes, in subsarcolemmal space, and in myoblast.


CONCLUSIONS
Desmin and vimentin were colocalized in the same intermediate filaments. More vimentin existed in the less differentiated myocytes, although a small number of desmin filaments were already found in undifferentiated myoblasts. These intermediate filaments may not only connect myofibril bundles, cell organelles, and cell membrane but also provide a basis for myofibrillogenesis that is similar to relation between connective fibers and parenchymal cells.
Yang
Y
Y
Department of Veterinary Anatomy, Faculty of Agriculture, Yamaguchi University, Japan.
Makita
T
T
D003893:Desmin / Q000378:metabolism* / Q000648:ultrastructure; D005314:Embryonic and Fetal Development; D005333:Fetus / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D018482:Muscle, Skeletal / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D014018:Tissue Distribution; D014746:Vimentin / Q000378:metabolism* / Q000648:ultrastructure
D003893:Desmin; D014746:Vimentin