Ultrathin frozen sections for Electron Microscopy: Some personal recollections

Abstract

In the mid-1960s, while on the faculty of the Anatomy Department at Stanford, I was particularly interested in the cell biology of steroid-secreting cells. I had studied the ultrastructure of these cells, and was anxious to trace the pathways of steroid hormone synthesis and of the secretion from the cell. An invitation to speak at an international steroid congress in Milan, Italy, in May 1966, afforded me an opportunity to travel in Europe before the meeting started. During that trip I had a very enjoyable visit with Dr. Wilhelm Bernhard, in the Paris suburb Villejuif. He had developed means of cutting ultrathin frozen sections (UFS) of fixed tissue on a Sorvall MT-1 ultramicrotome maintained in a freezer at about −35°C. As the sections were cut, they floated off on a solution of dimethyl sulfoxide and water, from which they were picked up on EM grids, treated for cytochemistry, stained with uranyl acetate, and then viewed by EM.