Thomas R C, Wilson V J
Science. 1966 Mar 25;151(3717):1538-9. doi: 10.1126/science.151.3717.1538.
Glass microelectrodes filled with a saturated solution of methyl blue or fast green in 1.0M potassium acetate can be used to mark penetrated ne. urons from which intracellular recordings have been made. Many cells can be marked in one experiment and can easily be located in subsequent histologic section.