THE BI-LOBED FORM OF THE VENTRAL PANCREAS 



IN MAMMALS 



FREDERIC T. LEWIS 

 Harvard Medical School, Boston, Mass. 



TWELVE FIGURES 



Among some pig embryos sectioned for class use, the writer, in 

 1907, fomid one in which the intestine was nearly encircled by 

 pancreatic tissue. This unusual condition was due to the pres- 

 ence of a large left lobe of the ventral pancreas. The specimen was 

 referred to Dr. Thyng for further study, and he described it 

 briefly in vol. 7 of this Journal (1908, p. 493). He suggested that 

 the annular pancreas of man may have a similar origin. Quite 

 apart from this possibility, which will be considered later, the 

 condition in the pig is of interest because of its frequent occur- 

 rence, and because it represents a more symmetrical development 

 of the ventral pancreas than is normal. The great variation in 

 the ventral pancreas, even in its earliest stages, renders its de- 

 scription difficult, and accounts for the conflicting results of careful 

 investigations. 



It is generally agreed that as soon as the ventral pancreas 

 becomes an easily recognized structure, it is a median ventral 

 outgrowth from the ductus choledochus near its intestinal orifice. 

 Preceding this stage, it is said to be represented by a pair of knob- 

 like epithelial buds, situated one on either side of the hepatic 

 diverticulum or primitive ductus choledochus. The paired 

 stage is shown in fig. 1, from a pig embryo of 3.6 mm. It has not 

 been previously recorded for the pig, but corresponds closely 

 with the condition found in a sheep embryo of 4.5 mm. by Stoss 

 and clearly figured for the same species by Choronshitzky. It 



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