THE NEURAL TUBE AND ITS DERIVATIVES 



33 



ventricular foramina, which at this stage are relatively large. The lamina 

 terminalis, connecting the two hemispheres in front of the third ventricle, repre- 



Diencephalon 



Pallium 



Mesencephalon 



Cephalic 

 flexure 



D 



Thalamus 



Pallium 



\Iesencephalon 



Optii 

 cup 

 Ponline flexure j 



Myelencephalon ? 



Meten- 

 cephalon 

 Corpus striatum. 

 Optic recess 



Hypoihalamus 



Medulla oblongata 



Fig. 15. Reconstructions of the brain of a 7 mm. embryo: A, Lateral view; B, in median sagittal 



section. (His, Prentiss-Arey.) 



sents in a certain sense the rostral end of the brain. Immediately behind this 

 lamina is a portion of the telencephalic cavity which forms the anterior part of 



Cerebral peduncle 

 Hypothalamus .^ 

 Epithalamus \ ^aJL 

 Thalamnf; 

 Diencephalon- r 



Pallium^ 

 Telencephalon- -' 



Cerebral aqueduct 

 [.^Mesencephalon 



^^,RhombencepJialic isthmus 



Cerebellum 

 Metencephalon 

 Rhomboid fossa 



^Myelencephalon 



1234 > 

 Rhinencephalon | Corpus striatum Pans 

 Lamina terminalis 



Spinal cord 



Fig. 16. A median section of the brain of a 13.6 mm. human embryo: 1, Optic recess; 2, ridge 

 formed by optic chiasma; 3, optic chiasma; 4, infundibular recess. (His, Sobotta.) 



the third ventricle. The further development of these structures is readily 

 traced in Fig. 17, which represents the brain of a human fetus of the third 



3 



