title: [Rhabdomyosarcoma in childhood. II. Ultrastructure].
abstract: The diagnosis of rhabdomyosarcoma was established or proved by electron microscopy in two thirds of 21 cases. Histological classification was not adequate or formulated as "undifferentiated sarcoma" in half the cases. Electron microscopy did not succeed in one third of cases and rhabdomyosarcoma was classified according to simultaneous or successive study. Undifferentiated tumour cells resembled myoblastema cells of the 5th-6th gestation weeks. Differentiation of myoblasts and myotubes corresponded to the muscle development of the 7th-16th weeks. Immature cells showed features of fibroblasts and myofibroblasts in most cases of embryonal rhabdomyosarcoma. Alveolar rhabdomyosarcomas were characterized by exclusive myoblastic differentiation. Different cellular sources were discussed in rhabdomyosarcomas with differentiation into one cell type or into various mesenchymal cells.
mesh_terms: D002648:Child; D006801:Humans; D012208:Rhabdomyosarcoma / Q000648:ultrastructure*
vernacular_title: Rabdomyosarkom v dĕtském vĕku. II. Ultrastruktura.