TRANSVERSE SECTIONS 



III 



ica venae cavae (caval mesentery) located to the right of the mesentery 

 (Fig. 107). This vein now carries blood direct to the heart from the right pos- 

 terior cardinal and right subcardinal, by way of the liver sinusoids and the right 

 vitelline trunk (common hepatic vein). Eventually these four vessels form the 

 unpaired inferior vena cava. (For the development of the inferior vena cava see 

 Chapter IX). 



First aortic arch Seessel's pocket 

 Second aortic arch 

 Pharyt 



Isthmus 



Thyreoid 

 Third aortic arch 



Notochord 



Fourth aortic arch 

 102 



Fifth aortic arch and 

 pulmonary artery 



103 

 Esophagtis 



104 



Trachea 

 105 



R. lung 

 106 



107 



Stomach 



108 



Cceliac artery 



iog 



Ventral pancreas 

 Dorsal pancreas 

 Gall bladder 



L. umbilical vein 



Vitelline artery 



Cephalic limb of intestinal loop 



Dorsal aorta 



Int. carotid artery 



101 



Pituitary body (pharyngeal 

 lobe} 



Optic recess 

 102 



Telencephalon 

 Ventral aorta 



Bulbus cordis 



Interventricular foramen 

 L. horn of sinus venosus 



L. umbilical vein 

 Tail-gut 



Cloaca 



107 



Spinal cord 

 in 



112 



108 



Metanephric anlage 



zoo 



L. umbilical artery 



"Anastomosis between 

 dorsal aorta 



Allantoic stalk 

 L. dorsal aorta 

 Mesonephric duct 



Artery to mesonephros 

 Mesentery Caudal limb of intestinal loop 



FIG. 100. Reconstruction of a 6 mm. pig embryo in the median sagittal plane, viewed from the 

 right side. The numbered heavy lines indicate the levels of the transverse sections shown in Figs. 

 101-112. The broken lines indicate the outline of the left mesonephros and the course of the left um- 

 bilical artery and vein. The latter may be traced from the umbilical cord to the liver where it is sec- 

 tioned longitudinally. (Original drawing and reconstruction by Mr. K. L. Vehe). X i6j^. 



TRANSVERSE SECTIONS 



Having acquainted himself with the anatomy of the embryo from the study 

 of dissections and reconstructions, the student should examine serial sections cut 

 in the plane indicated by guide lines on Fig. 100. Refer back to the external 

 structure of the embryo (Fig. 88), to the lateral dissection of the organs (Fig. 



