title: An improved method for extracellular marking of electrode tip positions in nervous tissue.
abstract: The Alcian blue method for extracellular marking of recording sites has been improved by filling the glass micropipettes with 3% Alcian blue 8GX or 8GS in 3M KCl buffered to pH 5.2 with 0.05M Potassium acetate. By filling the microelectrodes with a strong electrolyte (3M KCl) the same low resistances (5--25 M omega) and recording properties as conventional micropepettes are preserved. Currents of 0.5--1 microA for 1--3 min passed through the different electrode connected as anode, resulted in coloured spots of 10--100 micrometers in diameter. There was a positive correlation between the amount of curren passed, and the size of the spots. The localization of the electrode tips was successful in more than 80% of all cases. The dyemarks remained for at least 5 cays in vivo and resisted many histological procedures.
mesh_terms: D000423:Alcian Blue / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism; D001931:Brain Mapping / Q000379:methods*; D002685:Chiroptera / Q000502:physiology; D004586:Electrophoresis; D007211:Indoles; D007245:Inferior Colliculi / Q000502:physiology*; D051379:Mice; D008839:Microelectrodes
chemical_list: D007211:Indoles; D000423:Alcian Blue