EBEN J. CAREY 



75 



In the earlier stages the esophageal epithelial tube grows relatively 

 more rapidly in diameter than in length (Figs. 16 and 17). In the 9.5 

 mm. embryo the esophageal epithelial tube measures 0.04 mm. in 

 diameter and 1.3 mm. in length; in the 14 mm. embryo the diameter 

 is 1 mm. and the length 2.1 mm. Therefore, the esophageal epithelial 

 tube is growing relatively more rapidly in width than in length/ from 

 the 9.5 to 14 mm. embryonic stages. 



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Fig. 18. Curves of differential growth in area of the tracheal and esophageal 

 epithehal tubes. These curves show strikingly the more rapid growth in the 

 same unit of time of the tracheal tube over that of the esophageal tube. Note 

 that between embryos 6 to 10 mm. in length there is an absolute decrease in 

 area of the tube. This decrease is concomitant with the rapid descent of the 

 stomach. This decrease in area is due to stretching as the result of traction 

 caused by the descent of the stomach. After the stage of the 10 mm. embryo, 

 growth in area of the esophagus rapidly progresses. 



