HUMAN EMBRYO AT SIX WEEKS 



279 



Fig. 187. End of the embryonic 

 period, about 6 weeks. (From Julius 

 Kollman, Handatlas der Entwick- 

 hingsgeschichte des Men sc hen. Ver- 

 Iag von Gustav Fischer, Jena.) 



At about this time the pronephros degenerates and the mesonephros begins 

 forming. 



Human embryo at six weeks 



At six weeks of age the embryo is about 12 mm. long (Fig. 187). The 

 head structures are more highly developed, and the arm and leg buds have 



