REVERSIBLE AND REPRODUCIBLE IN VIVO STAINING OF MOTOR ENDPLATES BY USE OF THE ACETYLTHIOCHOLINE‐IODIDE METHOD

Abstract

In vivo staining of motor endplates was carried out in the anterior tibial muscle of the rat, using the acetylthiocholine-iodide staining method of Koelle and Friedenwald. A strong and distinct endplate staining was obtained after incubation in the staining solution for only one minute if the epimysium had been removed from the muscle. Staining with intact epimysium gave a less satisfactory result if the incubation time was 3 minutes, but it was excellent after incubation for 10 minutes. At re-examination 5 or 30 days later, the initial staining had disappeared in all animals, and a second staining at this time gave just as good results as on the first occasion. The inflammatory reaction in the muscle was more severe with removed epimysium than with intact epimysium, and the staining solution had a slight local toxic effect compared with 0.9% NaCl. Staining with intact epimysium should therefore be preferred if possible.