The presence of granules in the brain has been known f o r some time. A few of the workers in this field have studied the granules which are intracellular. Some of these workers believe that these granules are given off from the cells and thereafter exist as intercellular granules, either furnishing energy for the growth of the nerve fibers or taking part in synapses. There are other writers who do not distinguish between the intercellular and the intracellular granules of the brain.
A few years ago we began the study of human brain cells in tissue cultures. The first thing to strike the eye in these cultures was the great mass of fine granules along the edges of the explanted tissue. Usually these granules are not seen in cultures of other tissues. Not all the edges of the transplanted brain had these granules, but many of them did. They were more noticeable in roller tube cultures than in hanging drop cultures. Indeed the granules were so conspicuous and so numerous that we began a study of them to see what we could find out about their origin, structure, function and fate, and which parts of the central nervous system contained them.
MATERIAL
We used brains of chick embryos from 40 hours to 21 days old; brains from white rats 1-6 days old and from an adult &4 grant from the Faculty Research F u n d has materially aided this research.