[Morphogenesis and histogenesis of experimental malignant hemangioendothelioma].

Film preparations, various histological stains, autohistoradiography and electron microscopy were used to study morphologic changes occurring in the course of formation of vascular kidney tumors in male CBA mice after subcutaneous injection of 1.2-dimethylhydrazine. Twenty-thirty animals were examined every 4 weeks up to 45-50 weeks. In mice, renal capsule (site of malignant hemangioendothelioma growth) is avascular. Blood vessels developed due to "formation of lumen" in bands of anastomosed cells. Endothelium of the newly formed vessels originated from multipotent mesenchymal cells. Also, intracytoplasmic formation of vascular lumens was observed. The initial neoplastic vascular structure (telangiectases) were registered after 20-30 weeks. They were composed of markedly atypical cells characterized by columnar shape, high nucleo-cytoplasmic ratio and high proliferative activity. Further progression was associated with the development of cavernous hemangioma-like tumors bearing cytologic signs of malignancy as well as well- and poorly-differentiated hemangioendotheliomas.