I came across this image in an article published by Dr. Olney. This is an image of hypothalamus tissue exposed to MSG over time. The white tissue is necrotic.
Dr. Olney also did research on the effects of MSG on weight gain. Below are two rats from the same litter. The left rat was given MSG and the right rat is the largest rat from the litter given no MSG (serving as experimental control).
Here is a link to the actual article published in 1991: