A morphometric study of the microvasculature of a rat glioma.

Intracerebral tumours were produced in BD IX rats by the inoculation of neoplastic astrocytes. Following perfusion-fixation, 1.0 micron sections were stained with toluidine-blue and photographed so as to construct photomontages embracing deep tumour, tumour edge and surrounding brain. Thirteen montages from 9 tumours were studied. Successive 200 micron samples were analysed with a digitizing tablet and, for each sample the following were measured: the number of vascular profiles per unit area, the mean vessel circumference and diameter and the approximate fractions of the sample occupied by tumour and necrosis. Towards the tumour centre, vascular density dropped to 20% of that for normal cortex but vessel size more than doubled. The surface area fraction of the vessels reached a maximum at the tumour edge. These results provide not only an anatomical framework for both a variety of physiological studies and for the investigation of angiogenesis in this system but also have pharmacokinetic implications for the treatment of brain tumours.