ATRESIA OF THE ESOPHAGUS IN THE EMBRYO OF THE 



LOGGERHEAD TURTLE (CARETTA CARETTA): A 



NORMAL DEVELOPMENTAL CONDITION. 



BY H. E. JORDAN. 



INTRODUCTION. 



In a series of embryos of the loggerhead turtle collected and used 

 originally for a study of the history of the primordial germ-cells, it was 

 noticed that the esophagus was solid for a greater or less extent, 

 approximately from the point of origin of the respiratory anlage to its 

 bifurcation into the bronchi, from the eleventh to the thirty-second day 

 of incubation. At the latter stage the esophagus is still occluded at its 

 oral end, though now fenestrated for a considerable extent caudally; 

 and it seems probable that the esophageal atresia persists practically 

 to near the end of the incubation period (8 weeks) at the level just 

 behind the opening of the larynx. 



The points of special significance in regard to this material are: (1) 

 the relatively longer persistence of the occlusion than has yet been 

 described for any other form; (2) the absence of contributory yolk in 

 the stenosed area ; (3) close relation to the point of origin of the respira- 

 tory anlage, which fact may disclose its possible functional significance. 



Balfour was the first (1878) to describe a similar phenomenon in the 

 esophagus of certain selachii. Kreuter (1903) confirmed these obser- 

 vations in the case of Pristiurus and Torpedo. Dean (1897) reports 

 a solid esophagus in larvse of Amia calva. An occluded esophagus is 

 said to occur also in certain bony fishes e. g., herring, trout, salmon 

 (Balfour, Oppel). In cyclostomes the esophagus remains patent 

 throughout development (Kreuter). In certain amphibia (Bufo, 

 Rana) the esophagus becomes occluded, in part through the medium of 

 contributory yolk-globules (Meuron, 1886); and the same is true for 

 certain reptiles (Anguis fragilis, Oppel, 1891; Lacerta, Meuron, 1886). 

 According to Meuron, the esophagus of the chick embryo of the fifth 

 day is occluded for a length of 115 microns, but regains partial patency 

 again in the sixth day through the appearance of vacuoles. Lillie de- 

 scribes the esophagus of the chick embryo as completely occluded 

 immediately behind the glottis from the eighth to the eleventh day, 

 " owing to proliferation of the lining cells." 



Kreuter (1905) was the first to describe an epithelial obliteration of 

 the esophageal lumen in the human embryo, contrary to the teaching 

 of Kollmann and other embryologists that no solid stage of the esopha- 



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