182 



THE ENTODERMAL CANAL AND THE BODY CAVITIES 



nective tissue. The parietal lining is derived from the somatic layer of 

 mesoderm and the visceral covering from the splanchnic layer. 



Esophagus 



Pericardial cavity 

 Ventricle of heart 



Ventral ntesocardium 



Liver 



Ventral mesentery 

 (falciform ligament) 



Dorsal mesocar- 

 dium 



-Septum transversum 



. Stomach 

 .B 



- Ventral mesentery 

 (lesser amentum) 

 'Dorsal mesogastrium 



Dorsal pancreas 



Mesentery 

 Mesocolon 



Mesorectum 



FIG. 189. Diagram showing the primitive mesenteries of an early human embryo in 

 median sagittal section. The broken lines (A, B, and C) indicate the level of sections A, B t 

 andj C, in Fig. 190. 



Neural lube 



B C 



FIG. 190. Diagrammatic transverse sections of an early human embryo. A, Through 

 the heart and pericardial cavities; B, through the fore-gut and liver; C, through the intestine 

 and peritoneal cavity. 



The primitive ccelom lies in the horizontal plane, as in Fig. 1 88. Coin- 

 cident with the caudal regression of the septum transversum, the peri- 

 cardial cavity is bent ventrad and enlarged (Fig. 191). The ventral 



