EFFECTS OF ENVIRONMENT ON CONTROL 



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Figure 10-15. The Neuro-Muscular Synapse (Motor End Plate). Lower right: muscle 

 myofibrils (mf) bounded at their top edge by a continuous folded membrane. 

 Across the gap (~500A) is the nerve-cell membrane, touched in places by fingers 

 (sf) from the Schwann cell (Sc). Note the many little (~100A diameter) vesicles (v). 

 The theory is that these contain acetylcholine which is released during the passage 

 of an impulse; and that in their thermal motion they bounce against the membrane 

 and locally depolarize it, thus to give rise to the micro end-plate potentials which 

 occur even when the nerve is at rest. Also marked: nerve ending (n.e.), mitochon- 

 drion (mit.), and connective tissue fibers (c.t.f.). Scale af top left: 1 micron. (Cour- 

 tesy of B. Katz, Department of Biophysics, University College, London, and of 

 J. Physiol.) 



