THE EFFECT OF ISCHEMIA ON THE PERMEABILITY OF THE PERINEURIUM TO PROTEIN TRACERS IN RABBIT TIBIAL NERVE

The influence of ischemia on the permeability of the perineurium to protein tracers was studied in rabbit tibial nerve. Intravital ischemia was produced by a pneumatic cuff around the thigh and the effects of long-lasting permanent ischemia were investigated in postmortem experiments. The permeability was tested fluorescence microscopically by injections of albumin labelled with Evan's blue (EBA) around the nerve. The diffusion of EBA into the endoneurium of control tibial nerves was prevented by the perineurium. This “barrier” function of the perineurium resisted ischemia of even 24 hours’duration but after 48 hours of ischemia the tracer penetrated the perineurium and spread widely in endoneurial spaces. This diffusion barrier is therefore markedly resistant to ischemia and postmortem changes.