308 



A.L. — > 



THE PINEAL ORGAN 



Post. 11-%^ 



p.a- 



A.L.- 



P.L. 



C D 



Fig. 214. — Transverse Sections of the Pineal Region of a 6-cm. Human 

 Embryo, and of a 4 J -month fcetus. (R. J. G.) 



A — Section through the basal part of the main pineal diverticulum of a 6-cm. 

 human embryo showing, in the upper part of the photograph, the solid 

 anterior lobe. Below this is the main pineal diverticulum, the wall of which 

 shows proliferating cords of ependymal cells growing outward, into the 

 surrounding tissue. Below the pineal evagination is a section through the 

 infrapineal recess, the epithelial lining of which is assuming a columnar 

 type. Fibres of the posterior commissure are seen at the sides and below 

 the pineal region. 



B — Coronal section through the pineal region of a 4. \ -month human foetus showing 

 the relation of the dorsal diverticulum (suprapineal recess) to the pineal 

 gland. Clusters of elongated choroidal villi project into the lumen of the 

 diverticulum. The pineal gland shows partial subdivision into an anterior 

 and posterior lobe. 



C — The pineal gland more highly magnified, showing the ingrowths of vascular 

 processes of the pia mater between the outgrowing neuro-epithelial cords. 



D — Peripheral portion of the gland X55 D., showing pale areas containing a 

 central core of vascular pia mater, alternating with dark zones composed of 

 neuro-epithelial cords. 



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