Blood-brain barrier integrity and host responses in experimental metastatic brain tumours.

The effect of brain implants of Walker 256 carcinosarcoma tumour cells on the integrity of the blood-brain barrier was examined in rats using labelled albumin, horseradish peroxidase and trypan blue. Barrier integrity was intact within 1 hour of implantation but was gradually reduced within the tumour after 3.5 days. This was related to alterations in the fine structure of the tumour capillaries. Dissociated tight junctions were apparent within the tumour centre, but no fenestrated endothelium or gap junctions were observed by electron microscopy.