Then when I introduced microelectrodes from above, I actually was pretty skilled at preparing the microelectrodes. Which had to be done almost every day because the electrodes were very fine tip, so that they could penetrate the nerve and muscle cells without damaging them too much.

When they were filled with a concentrated solution of KCl... KCl because that was the principal intracellular cation. They measured anywhere from 10 to 100 megaohms, so not only were they fine tip, but they're extremely high resistance, requiring very specialized amplifiers. Which I had learned a bit about back at Cornell because I met a man named Ernie Amatniak, who had a company making these amplifiers, providing them to some of the senior neuroscientists in New York. Harry Grundfest, Eric Kandel, and a number of other people.

I would pull the electrodes and be prepared the day after plating the neurons and muscle to record. Probably the most exciting afternoon at the NIH was when I recorded the first synaptic events. I was in a small room in my lab, just adjacent to the tissue culture hood. And turned out the lights so I can see the oscilloscope screen and there, sure enough, there were these small blips on the scope, which were miniature endplate potential. I almost screamed with joy. Ran out into the hall, said I've formed synapses. And people came from all over the lab to see what the hell I was talking about. That was the beginning of my career in cell cultures and from there, it went on to a number of different projects and students.