The use of slotted grids for electron microscopic radioautography

A method for electron microscopic radioautography on slotted grids is presented which allows examination of the distribution of silver grains over sections of entire structural units without interference by grid bars. Tissue sections of a size such as to fit the opening of the grid slot are placed on slides coated with a Formvar film of sufficient strength to permit transfer of the completed radioautograph onto the grid and to support it over the slot. Sections are block stained prior to radioautography to minimize the risk of loss of the radioautograph during the procedure.