An alternative method to stereotactic inoculation of transplantable brain tumours in large numbers of rats

The rat 9L, gliosarcoma brain tumour model has been widely used in brain ca ncer studies. Intracerebral implantation of the cells in the parietal lobe of the brain has been performed using the stereotactic or freehand inoculat ion methods. For large numbers of rats, we wished to develop a method more accurate and precise than the freehand method, but less labour intensive th an the stereotactic method. A template implantation technique was developed and compared quantitatively with the stereotactic method. Rats were inocul ated with either the template or stereotactic method at doses of 1000, 5000 , 10 000, 20 000 or 40 000 cells. Results of this comparison showed that th e template method is precise and accurate for tumour placement within the b rain cortex, and decreases labour requirements. Mean survival rates between groups were not significantly different at doses of 5000, 20 000 or 40 000 cells inoculated. Significance was seen at the low dose of 1000 cells (P < 0.001). This was attributable to an absence of tumour growth in five of si x stereotactic rats in this group. Significance was also seen at the 10 000 dose level (P < 0.05) with the stereotactic rats again surviving longer th an the template rats. However, in this case all the stereotactic rats had t umour growth. Brain weights did not differ significantly between groups, ex cept at the 1000 dose level where no growth of tumour occurred in five of t he six stereotactic animals. Body weight gain within one week following sur gery did not differ significantly between any of the groups at alpha = 0.05 . Studies on rat cadavers showed no statistical difference in placement mea surements between the stereotactic and template methods. These results indi cate that the template method for intracerebrally implanting tumour cells i n rats provides a precise, accurate and rapid procedure that maximizes repr oducibility with a significant reduction in labour requirements, when compa red with the conventional stereotactic methodology.