Vascular permeability in transplantable murine gliomas: morphological correlation with tracer studies

Invasive astrocytomas were produced in mice by intracerebral injection of a cell line obtained from a spontaneous murine astrocytoma. These tumours grew in the cerebral hemispheres and, in many cases, extended through the needle hole in the skull to give rise to large extracranial tumours. On injection of the tracers, Evans' blue or horseradish peroxidase (HRP), into the femoral vein, differences were noted in the vascular permeability of the intracerebral and extracranial tumours; the latter alone being stained. Ultrastructurally, small amounts of HRP were localized on the luminal membranes of the vascular endothelium in intracerebral tumours, while in extracranial neoplasms, the tracer was present in the widened extracellular space and in the cytoplasm of macrophages and neoplastic cells. Accordingly, endothelial fenestrations, open junctions and irregular vessels with hypertrophic endothelia were seen exclusively in extracranial neoplasms. These anomalies in the vasculature of intracerebral and extracranial components of VMDk P 497 tumours may have important implications in chemotherapeutic studies using this glioma model.