PLATE 5 



EXPLANATION OF FIGURE 



35 Reconstruction of the vascular channels of the lower cervical and thoracic 

 regions in a 21.5 mm. pig embryo (series 192, slides 16-24 inclusive), X 50. Sinistro- 

 dorsal view. 



A, precardinal division 



B, postcardinal division 



1, left jugular lymph sac 



2, thoracic duct approach 



3, anterior lymphatic plexus or subse- 

 quent common trunk of the right 

 and left thoracic ducts 



4<l, 4s, discontinuous thoracic ductan- 



lagen 

 5d, 5s. right and left thoracic duct an- 



lagen continuous with lymph sac 

 X, X, extent of continuity in the duct 



anlagen connected with the lymph 



sac 



7, spur or vestige of the former oblique 

 vessel 



8, dorsal segmental veins 

 .9. internal jugular vein 

 10, left precardinal vein 



lid, lis, right and left postcardinal 



veins 

 12ls, plexiform remnants of the left 



supracardinal line 



13, aorta 



13b, ductus arteriosus Botalli 



13d, right subclavian artery 



13s, left subclavian artery and branches 



14, left sympathetic nerve trunk 



15, vagus 



16, recurrent laryngeal nerve 



17, oesophagus 



18, trachea 



21, left Cuvierian duct 



22, left subclavian vein 



23, cephalic vein 



24, external jugular vein 



26, subclavian approach of the jugular 

 lymph sac 



474 



