JORDAN XIV 



PLATE 4 



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8 



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9 



Sinistro-dorsal portion of transverse section ot ^j-dav embrvo at level of transition 

 from esophagus (e) to the stomach. The apparent obliquity of the section is due 

 to the sinistral rotation of the rarciiac end of stomach (c. s) . The approximately 

 transverse position of stomach at these stages accoim's tor its being cut longitud- 

 inally in a transverse section of the embrvo. Note the extensive! v fenest rated 

 condition of the caudal portion of the esophagus (e, \\ithin the rectangle) at this 

 stage, (r). rib; (c), pleural ctvlom ; (I), left IUIIL; : I'O, right dorsal aorta; (6), right 

 primary bronchus. Photo, x 17. 



More highly magnified photomicrograph (x 300), of portion of esophagus included 

 within rectangle in preceding figure, (x), earlier irregular and several-layered con- 

 dition of lining epithelium of esophagus during period of fenestration of solid 

 esophagus in the process of reestablishment of patency of its lumen ; (?/) , a delicate 

 nucleated septum, in process of reincorporation within the later regular single- 

 lavered lining of the open esophagus; (2), portion where lumen is lined with the 

 later (transient) single-layered epithelium of prismatic cells. 



