Abstract
We have used serial microangiography and radioactive 133Xe to study microvascular morphology and to quantify blood flow in Walker 256 carcinomas implanted in rat tails during growth and immune rejection. Two tumour groups were indentified. Group A grew rapidly with a 2 to 6 times increase in blood flow, and caused death in 10 days. Group B grew more slowly and increased blood flow 2 to 4 times. At 6 to 8 days after implantation the B tumours diminished in size, blood flow decreased and extensive lymphocytic infiltration developed. By 21 days all evidence of the tumour disappeared. The rejection appears to be cell-mediated and the high incidence of tumour rejection (65-70%) to be related to the number of tumour cells and/or presence of foreign cellular debris in the inoculum. Microangiographic changes during immune rejection were specific and included marked tortuosity of feeding vessels and a “ghost-like” fading out of tumour vessels quite unlike the appearance of necrosis.
