PLEURO- 

 ERICfiRDIAL 

 .■•:'■ CANAL 



NEURAL TUBE 



DORSAL AO 



DORSAL CLOSING 



CONTRIBUTION 



SPLANCHNOPLE 



MESODERN 



DUCT OF CUV 



DORSAL CLOSIN 



CONTRIBUTION 



SOMATOPLEU 



MESODER 



LATERAL 



MESOCARDIU 



SINUS VENO: 



HEART (ATRIU 

 LIVER 



STOMACH DORSAL 



MESOGASTRIUM 



ORSAL AORTA 

 NEURAL TUBE 



Fig. 362. The lateral mesocardia form the initial division of the embryonic coelom. 

 (A-1 and A-2) represent idealized sections through the vertebrate embryonic body in a 

 plane between the caudal limits of the sinus venosus and the anterior extremity of the 

 potential liver region of the embryo. (A-1) Diagram of the initial stage of separation 

 of the pericardial and peritoneal coelomic cavities in many vertebrates. Two dorsal and 

 two ventral recesses or passageways above and below the lateral mesocardia and lateral 

 horns of the sinus venosus are evident. These passageways communicate with the peri- 

 cardial and peritoneal divisions of the primitive coelom. (A-2) Separation of primitive 



860 



