[New data on the histogenesis of connective tissue tumors]

The normal skin and adipose subcutaneous tissue, desmoid fibroma, lipomas with varying proliferative activity, fibrosarcoma, malignant fibrous histiocytoma, epithelioid leiomyoma are studied by means of electron microscopy and electron microscopical radioautography. It was found that the walls of the smallest vessels contain cells which are the source of a permanent physiological renewal of a different type of the connective tissue. In proportion to differentiation and gradual removal of these cells from the vascular wall their proliferative and metabolic activity is more and more decreasing. Thus, the vessels represent not only the transport-nutritive system but the central generative structure of the connective tissue as well. Pluripotential mesenchymal cell of the vascular wall which under physiological conditions is differentiating in the direction of fibro-, angio-, lipo- or osteogenesis, due to the influence of oncogenic factors gives rise to the development of benign and malignant tumours of fibrous, vascular (angiomas), smooth muscle, adipose and bone structure. This can be most demonstratively checked using electron-radioautography of tumourlike conditions and relatively slow growing tumours.