ON THE STRUCTUEE OF THE HUMAN UMBILICAL VESICLE. 



BY 



ARTHUR W. MEYER, 



From the Anatomical Laboratory of the Johns Hopkins University. 



With 5 Text Figures. 



In the history of embryology the discovery and interpretation of the 

 yolk sac must always remain one of the most interesting chapters. The, 

 to us, naive speculations as to its significance, at a time when " anato- 

 mists feared to make a thorough examination of ova and preferred rather 

 to preserve them in alcohol," lend a peculiar interest to the study of the 

 early literature on this subject. Many of the embryologies and anato- 

 mies of that time give much attention to the yolk sac, and it is not un- 

 common to find several chapters devoted to the discussion. 



The credit for the first description of the human yolk sac seems to lie 

 between Hoboken and Noortwyck. Wrisberg, however, gave the first 

 accurate description of it, in full cognizance of the fact that what he 

 described was a yolk sac comparable to the yolk sac of birds. The latter 

 is referred to by Wrisberg as the " vesicula erythroides " of von Pockel, 

 imconscious of the fact that von Pockel really described the allantois and 

 not the yolk sac, as he believed. It is possible that Noortwyck was the 

 first to recognize the yolk sac of the human embryo. Hoboken did not 

 recognize it, and, according to Mayer, this was left for the great Albinius 

 who first pictured a human embryo with the umbilical vesicle in situ. 

 It was this fact which caused Zinius, in his monograph, to refer to the 

 yolk sac as " de vesicula embryonis Albiniana." Neither this designa- 

 tion, nor that of " vesicula alba " of Hunter, found favor, however, for 

 both were soon displaced by the term " vesicula umbilicalis " first used 

 by Blumenbach. 



Up to 1835 the greatest diversity of opinion existed regarding the 

 functions of the yolk sac, and many interesting theories were advanced. 

 Oken, while recognizing the meaning of the organ and demonstrating its 

 occurrence in several of the mammalia, promulgated the idea that the 

 intestine arose in the vesicle itself. Kieser, in 1810, claimed to have 

 proven that the intestine develops in the yolk sac, and that it is then 

 slowly taken into the abdomen. Van Euysch and Ossiander, on the 

 contrary, took it for an hydatid and a pathological formation respec- 



American Journal of Anatomy. — Vol. III. 



