C. ESTABLE 



323 



in effect Del Castillo and Katz refer to the possibility of accounting for the 

 miniature end-plate potentials which they discovered by regarding them 

 as due to discharges of acetylcholine supposedly pre-existent in the 



^l»' 



Fig. 14 

 Parasyiuipscs (I) — Parasynapsis fibres — s. parasyn — in the cervical Cdrd 

 of an adult man. Tight bundle of closely placed a.xons. 



microvcsiclcs. However, there is no evidence that acetylcholine ions 

 gather as microvcsiclcs, and even less evidence that the microvesicles, 

 which exist in certain synaptic types, are 'quanta' of the chemical mediator. 

 Y 



