SPLANCHNOPLEURE 

 DIENCEPHALON 



MESENCHYME 



METENCEPHALON 



BLOOD VESSEL 



MESENCEPHALON 



Fig. 135. A section through the anterior end of a 48-hour chick embryo. 

 The diencephalon, mesencephalon, and metencephalon are transversed. The thin 

 wall at the extreme right of brain may be the roof of the mylencephalon. In the 

 section, right is dorsal ; left is ventral ; top is left side ; and bottom is right side 

 of head. The chorion, amnion, and splanchnopleure are shown. 



RATHKE'S POUCH 



DIENCEPHALON 



AORTIC ARCH 



PHARYNX 

 DORSAL AORTA 



ANTERIOR CARDINAL VEIN 

 MYELENCEPHALON 



VISCERAL POUCH 

 VISCERAL GROOVE 



Fig. 136. The hypophysis, aortic arch, and visceral pouch of a 48-hour 

 chick embryo. 



STOMODEUM 



LENS VESICLE 



OPTIC CUP 



DIENCEPHALON 

 AORTIC ARCH 



VISCERAL ARCH 



FIRST SOMITE 



ANTERIOR CARDINAL VEIN 



DORSAL AORTA 



Fig. 1 37. Optic cup and lens vesicle of a 48-hour chick embryo. 



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