30 TISSUES AND ORGANS 



known as the auriculo-ventricular node. It is probable that this 

 is nothing more than such a plexiforni collection of intercalated 

 cells which happens to be situated at a point where studies of the 

 function of the myocardium would lead one to expect to find it ; 

 it has attracted more attention than have the other similar 

 formations, simply because its significance seems to be understood, 

 and perhaps in part because it was the first such structure to be 

 discovered. 



The other or adult type of cell resembles the ordinary elements 

 of the myocardium very closely, but is always multi-nucleated. 



It must be realised that the separation into types of cell is 

 rather an artificial one, because transitions can be found between 

 cells of the embryonic type and those of the adult form just as 

 they can between the latter and the ordinary myocardium. 



