The Distribution of Material Inoculated into the Monkey Brain. ∗

Abstract

When conducting experiments with poliomyelitis virus, intracerebral inoculations are used extensively since monkeys are most consistently infected by this route. However, no data are available concerning the subsequent distribution of material inoculated in this manner. A large series of experiments was performed by us, in which the resultant neutralizing action of immune serum upon the virus was tested by direct inoculation of the mixtures into the brains of monkeys. During the course of this work numerous discrepancies in the results were observed. In an effort to account for the variations, among other factors, the influence of the method used to inoculate the serum-virus mixtures into the monkey brain and the eventual course of the material from the site of inoculation following its deposition were studied. The dispersion of the inoculum was followed by the addition of India ink to the mixtures.

Experiment I. 1.5 cc. of human serum was mixed with 1.5 cc. of a Berkefeld filtrate of a 5% virus suspension. This was the usual mixture which we had used in our neutralization test experiments. To this mixture 1 cc. of India ink was added. After thorough mixing, the material was injected into the right frontal lobes of 4 monkeys (Macacus rhesus), each receiving 0.25 cc, 0.5 cc, 1.0 cc, and 2.0 cc respectively, with a tuberculin syringe carrying & 3/4-inch, 26-gauge needle which was inserted through a small trephined opening made on the frontal bone approximately 1 cm. to the lateral right of the mid-line and 1 cm. anterior to the coronal suture. At the end of 2 hours, the monkeys were chloroformed and their brains and spinal cords examined at autopsy. The results are summarized in Table I.