SYMPATHETIC SYSTEM IN MAMMALS 



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Fig. 14. Transverse section through the oesophagus, the vagus trunks, and 

 the anlagen of the cardiac plexus in an embryo 13 mm. in length, X 100. 



origin in the sympathetic trunks still contain numerous " accom- 

 panying' 7 cells which are apparently migrating peripherally along 

 their fibers. It is probable, therefore, that the cardiac plexus 

 also receives cells from the sympathetic trunks after the sympa- 

 thetic cardiac nerves have become established. 



This stage in the pig may be compared with the human embryo 

 10.2 mm. in length described by His, Jr. ('91). He also observed 

 that, in this stage, the branches of the vagi are comparatively 

 free from cells, while the cardiac nerves having their origin in the 

 sympathetic trunks contain many cellular elements. He con- 



