Some characteristics of the mesenchymal stem cell of soft tissue tumors

"Soft tissue tumors" is an unnatural term, used by clinicians and for convenience by pathologists, which unites the neoplasms of mesenchymal origin as opposed to those of the soft epithelial tissues. Not included are the reticuloendothelial system, glia and supporting tissues. The mesenchymal stem cell, the cell of the embryonal connective tissue, exhibits in man and mammals the most pronounced embryonal potential. A restricted comparison to the embryonal potential in larval and pupal cells of invertebrates, such as in hemi- or holometabolic insects and to meristematic cells in vascular plants is justified. The great embryonal potential may explain why the mesenchymal stem cell, at present a hypothetical unit, is able to transform and differentiate into the connective tissue as such, the muscular, supporting and hematogenic tissues. The musculature comprises the bulk of the mammal's body weight. The development of the normal ontogenetic specialization as well as especially those differentiations leading to soft tissue tumors are comparatively shown in this publication and placed in the framework of vertebrate and invertebrate animals with true tissues.