Technology Review has a photo essay of how the brain has been visualized for the last 100 years. The above pic is a hippocampal neuron and it’s one of the sexiest neurons I’ve seen.
A newer twist on electron microscopy, developed in the 1980s, can reveal the internal structures of nerve cells. Researchers use a detergent to remove the cell membrane. Platinum and carbon are deposited onto the exposed surfaces to reproduce the cell’s interior features as a three-dimensional mold, which is then examined in the microscope.