ASPECTS OF INHIBITORY PATHWAYS AND SYNAPSES 



43 



interneuronal contacts being completely irregular inhibition cannot be based 

 on any specific localization or geometry of synapses; (ii) being dependent 

 neither from primary sensory nor from motoneurons it must be produced by 

 a third group of neurons acting probably through a humeral agent. These 

 cells may be present or absent in the preparations, and they develop later and 

 degenerate earlier than sensory or motor neurons. 



Fig. II. Deplanted vagus ganglion of larval n2wt (Pleurodeles walili). Sensory 

 neuron (X) with its process indicated by arrows. Bodian protargol method. 500. 



Fig. 12. Deplanted medulla oblongata, otherwise the same as Fig. 11. Two large 

 motor neurons (X) entering a muscle (arrow) of deplanted limb. 



Fig. 13. The same preparation as shown in Fig. 12. Terminal knobs (indicated by 



arrows) arising from sensory neurons and situated on the surface of motor 



neurons incorporated in this simplified "nervous system model." 



Fig. 14. Same as Fig 13. Terminal knob with its preterminal fibre, which in the 

 preparation can be traced back to deplanted sensory neuron. 



