THE BRAIN 



33' 



Mesencephalon Isthmus 

 Diencephalon ^?**^! Mctencephalon 



Telencephalonl 



Mesencephalon Isthmus Metenccphalon 



Diencephalon 



Telencephalt 



Mesencephalon 

 Diencephalon 



Telencephalon 



'ic reside 

 Myelencephalon 



Cervical flexure 



Myelencephalon 



Metenccphalon 

 'Myelencephalon 



ol 



FIG. 333. Brains of human embryos, from reconstructions by His: A, 4.2 mm. embryo 

 (Xao); B, 6.9 mm. embryo (X 16); C, 18.5 mm. embryo (X 4). o, Optic vesicle; in, infun- 

 dibulum; nt, mammillary body; pf, pontine flexure; ol, olfactory lobe; b, basilar artery; 

 p, Rathke's pouch (American Text-Book of Obstetrics). 



In the table on page 332 are given the primitive subdivisions of the 

 neural tube and the parts derived from them: 



