EARLY ORGANOGENY 



135 



Medullary plate 



al fold 

 Notochord 

 Archenteron 



Foregut 



Stomodeal 

 invagination 



Heart mesenchyme 



•er diverticulum 



Somatic mesoderm 

 hnic mesoderm 



Sagittal section of the open neural fold stage. (Redrawn and modified after 



Huettner.) 



Closing 

 blastopore 



Proctodeum 

 (anus) 



Hindg 



Midgut Oesophageal plug 

 IMotochord , I Neurocoel 



Hindgut 

 Rectum 



Neurenteric 

 canal 



Cloaca 

 Proctodeum 



Mesoderm 

 The 3 mm. frog tadpole: sagittal section 



Rhombocoel 



Tuberculum posterius 

 Mesocoel 



Diocoel 



Epiphysis 



Infundibulum 

 Optic recess 



Hypophysis 

 Oral evagination 

 Pharynx 

 Thyroid 

 Heart 

 Bile duct 

 Gall bladder (liver diverticulum) 



