Three-dimensional angioarchitecture in transplantable rat fibrosarcomas.

Three-dimensional angioarchitecture in a transplantable fibrosarcoma (SS) in F344 rats was investigated by scanning electron microscopy (SEM) of vascular corrosion casts. Tumours were produced in syngeneic rats by implantation of a tumour fragment from another SS tumour. Viable SS tumours, observed up to post-implantation (PI) week 5, showed a high degree of vascularization, consisting of arterioles and veins, and intertwining capillaries branching from such vessels. The capillaries showed numerous finger-like outgrowths, indicating active sprouting of endothelial cells and contributing to tumour growth. In contrast, SS tumours in rats given a single dose (4 mg/kg/bodyweight) of cisplatin at PI week 1 were reduced in volume, lacking in capillary outgrowths, and of low vascular density. Necrotic areas in SS tumours were surrounded by capillaries with sharp tips and wrinkled surfaces. Thus, the findings indicated differences in three-dimensional angioarchitecture between vigorously developing tumours and (1) tumours degenerating as the result of treatment with an anti-cancer drug, or (2) necrotic tumour tissues. SEM of vascular corrosion casts may prove useful for the evaluation of neovascularization in mesenchymal tumours.