By iontophoretically applying of CB—HRP (Chalera taxin B—Chain conjugation to horseradish perioxidase) into the left solitary necleus, the present experiment studied the efferent projection to the brain stem in chicken. The labeled terminals appeared bilaterally in the medular oblongata's parvocellular reticular necleus (Rpc ), the trigeminal descending necleus, the caudal olivary necleus, the intercalary neclers, the descending vestibular necleus. the medial vestibular necleus. In the pens, it appeared bil...