Transient cytokeratin expression in skeletal muscle during murine embryogenesis

Cytokeratin expression was investigated in paravertebral skeletal musculature of 10 d and 18 d old embryos as well as in adult NMRI-mice. The muscular nature of the evaluated tissue was evidenced by their expression of vimentin and desmin. Binding moieties for cytokeratin antibodies (polyclonal and monoclonal) could be demonstrated only in muscle cells of 10 d old embryos. Concerning subtypes, the mouse equivalents of the human cytokeratins Nos. 8, 18 and 19 could be made probable. The importance of the transient cytokeratin expression in murine embryonal skeletal muscle cells is emphasized, because this intermediate filament type is expressed in rhabdomyosarcomas too.