The ultrastructure of skeletal haemangiosarcomas induced in mice by strontium-90

Publisher Website
Google Scholar
Abstract
The commonest skeletal tumor occurring in male CBA and C3H mice injected with 7-13 .mu.Ci 90Sr (per mouse) was diagnosed with the light microscope as hemangiosarcoma. Nilsson, using male CBA mice injected with similar amounts of 90Sr, recorded the predominant tumor as fibroblastic osteosarcoma. To resolve the apparent discrepancy, samples of nonosteogenic tumors induced by 90Sr were examined with EM and their ultrastructure was compared with that described for fibroblastic osteosarcoma by Nilsson. The tumors diagnosed as hemangiosarcomas showed ultrastructural features not observed in fibroblastic osteosarcomas. Vasoformation was marked, the vascular channels varying in shape, size and character of their lining cells. Some vascular channels were lined by cuboidal cells, crowded together, and surrounded by a basement membrane. Others were lined by an attenuated endothelium and often formed networks. The tumor cells showed great variation in shape, size and ultrastructure and were sometimes enclosed by a basement membrane. The ultrastructure of the tumors described in this report supports the diagnosis of hemangiosarcoma, rather than fibroblastic osteosarcoma. The question of whether these hemangiosarcomas truly originate from vascular endothelium, or are mimics, is discussed.