In vitro staining of intramuscular nerve endings.

A method is described for vital staining of the human intramuscular nerve endings after the muscle biopsy has been removed from the patient. The muscle is transferred from the site of operation to the laboratory in oxygenated physiological saline. Methylene blue solution (0·015%) is injected into the muscle strip, and development of the stain can be observed under the microscope after exposure of the muscle to air. Permanent squash preparations can be made of the stained muscle and these are identical in appearance to muscles stained by injection of methylene blue in vivo.