THE ECTODERM AND ITS DERIVATIVES 



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prominent brain structures in the adult frog. They seem to originate 

 together and become separated only at the point of origin of the 

 olfactory nerves. However, each originates from the telencephalon on 

 its side of the brain. 



Dorsal to the anterior pallial commissure is the single median 

 anterior choroid plexus which develops as a thin and highly vascular 

 invagination from the roof just at the junction of the telencephalon 



Posterior Gerebellum 



choroid 



plexus 



Optic lobe (corpora bigemina) 



Mesocoel (aqueduct of Sylvius) 

 Posterior commissur 



Hobenular 

 ganglion 



Anterior 

 choroid plexus 



Olfactory lobe 

 Optic recess 



Optic chiosmo 

 Crura cerebri 

 Infundibulum 

 Pituitary 

 Mammillary recess 



Posterior choroid plexus 

 Spinal cord / Cerebell 



Optic lobe 

 (mesencephalon) 



Cerebral hemisphere 



Tuberculum posterius 



Mesocoel 



Optic recess 

 Optic chiasma 

 nfundibulum 

 Hypothalamus 



Anterior pituitary 



Late development of the brain of the frog tadpole. (Top) Pre-metamorphic 

 stage. (Bottom) Adult brain, schematized, reduced in size. 



