164 



The Nerves of the Atrio -ventricular Bundle. 



Plate 5. 



Fig. 3. — Monopolar ganglion cell ; one of six lying among muscle fibres of A.V.B. on 

 septal wall of calf. Zeiss comp. oc. 4, obj. 8 mm. 



Fig. 4. — Group of ganglion cells lying among nerve fibres in A.V.B. on left septal wall of 

 calf. 



A. = nerve fibre breaking up near muscle fibre and entering into muscle 

 plexus (not distinguishable with this low power). Zeiss oc. 6, obj. AA. 



Fig. 5. — Ganglion group in A.V.B. of calf, showing pericellular plexus around ganglion 

 cell (G. 2 ) containing fibres from three nerve cells. 



G.j = nerve cell which sends off process (dendrite) B, which branches 

 repeatedly within ganglionic group. One of these branches breaks up into a 

 network which embraces the adjacent ganglion cell G. 2 . 



C. = nerve fibre from an adjacent ganglion — not shown — which breaks up 

 into two branches : from these, twigs pass into plexus around G. 2 , others into 

 plexus around G. v 



D. == nerve fibre from nerve cell in same group as C, which breaks into 

 plexus around G. 2 . 



E. = varicose fibril clinging to A — neuraxis of G.j. 



Fig. 6.— Nerve cell in A.V.B. calf, containing a well-marked nucleus with halo. The cell 

 has several small processes which project, like sharp prickles. It has one long 

 process, A, which divides frequently ; its ultimate branches become varicose 

 and lie in close proximity to muscle fibres of A.V.B. Zeiss comp. oc. 4, 

 obj. 2 mm. 



Plate 6. 



Fig. 7. — Plexus around and adjacent to muscle fibres of A.V.B. of pig, immediately to 

 coronary side of its division into right and left septal branches. Zeiss oc. 4, 

 obj. 8 mm. 



Fig. 8. — Plexus around muscle fibres of left septal branch of A.V.B. of pig. Zeiss comp. 



oc. 4, obj. 2 mm. 

 Fig. 9. — Vasomotor fibres in small artery in A.V.B. of pig. 



S.N. = sensory nerve, S. = sensory ending, V.M.P. = plexus of fibres at 

 bifurcation of artery. 



Fig. 10. — Sensory ending in wall of artery in A.V.B. of cow. 



A. = nerve which breaks up into complex ending. 



