Vascular structure of the C3H mammary carcinoma, the B16 melanoma and the Lewis lung carcinoma in syngeneic, conventional mice and congenitally athymic mice.

The vascular system of three commonly used murine experimental tumours, the C3H mammary carcinoma, the B16 melanoma and the Lewis lung carcinoma, in syngeneic (C3D2F1/Bom or C57BL/6J/Bom) and athymic (BALB/c/nu/nu/Bom) mice was studied. The main vascular characteristics of each tumour, i.e. the mean vessel diameter, the total vessel volume and the distribution of the total vessel volume among vessels with different diameters, did not change upon transplantation from conventional to athymic mice. However, the length of vessels with diameters in the range 5-15 micron was for all tumours shorter in athymic than in conventional mice. The vascular volume of the B16 melanoma per unit histologically intact tumour volume in athymic mice (0.040 +/- 0.004) was considerably larger than that of five human melanoma xenografts previously studied (0.009 +/- 0.001 to 0.022 +/- 0.002). This difference was mainly due to occurrence of vessels with diameters in the range 55-145 micron in the B16 melanoma; vessels which were generally not observed in the human melanoma xenografts.