Transneuronal transport of wheat germ agglutinin‐conjugated horseradish peroxidase into trigeminal interneurones of the rat

Abstract

Intramuscular injections of either horseradish peroxidase (HRP) or wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) were made into the masseter muscle of rats. Both tracers labeled primary sensory neurones in the V mesencephalic nucleus, motoneurones in the V motor nucleus, and some motoneurones in die facial motor nucleus. WGA‐HRP labeled additional neurones in the V main sensory nucleus and the rostral pole of the V nucleus oralis. These were classed as interneurones because they lay in areas outside those known to contain either first‐order afferent or motoneurone somata. We argue that these were labeled by retrograde transport of tracer because they lay close to the V motor nucleus, and from some of them processes could be followed into the region of the V motor nucleus.