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JOHN SZENTAGOTHAI 



terminals of Renshaw cells on motoneurons. Considering also other analogous 

 findings, it must be assumed that inhibition is exerted on motoneurons and 

 also other types of larger spinal cord neurons by extremely fine synaptic 

 structures probably largely below the resolving power of the light microscope. 



Fig. 7. Diagram illustrating "remaining synapses" in isolated ventral column 

 preparation (a); b shows liow arterial supply of the isolated segment is influenced 

 by sagittal and horizontal incisions (broken lines); the dotted region of the 

 isolated ventral quadrant undergoes necrosis, d intact terminal knobs on small 

 (Renshaw) cell located as seen in diagram c. e around motoneurons only a 

 meshwork of extremely fine fibres remains intact. 



3. INHIBITORY PATHWAYS OF OCULOMOTOR NEURONS 



The oculomotor inechanisms offer wonderful opportunities to investigate 

 the anatomy of inhibitory pathways. Unfortunately the basic physiological 



