PANCREAS OF THE PKi 219 



Of these orders he did not relate the first two to the architec- 

 tural landmarks; jirobably they are not anatomical entities. The 

 third and fourth orders of Dogiel, however, have a definite mean- 

 ing. (Stohr gives practically the same thing in his well-known 

 textbook COO).) By finding a clearly demarcated unit in a 

 thick section of the pancreas injected through the duct, or by 

 carefully dissecting out one unit with fine needles, we can easily 

 relate the ducts of various sizes to the structures of the gland 

 (fig. 6). Exactly as in the eml^ryonic tissue, the single efferent 

 duct of the unit has four or five l)ranches. These are much less 

 regular than the intralobular ducts of the salivary glands, and 

 hence should not, perhaps, be dignified with a special name. 

 They scatter to the various parts of the unit, where each branches 

 two or three times to give off the straight ducts (3rd order of 

 Dogiel) or Schaltstiicke (fig. 6, s) ; these give rise to the very 

 tenuous twig-like preacinar ducts (fig. (>, p) whose branches are 

 the acini themselves. The acini seem to be terminal vessels. 

 Ram6n y Cajal and Sala ('91; quoted in Oppel '00, T. 3, p. 796) 

 state, from the study of silver-impregnated specimens, that there 

 are no anastomoses between the terminal acini in the frog, hake, 

 chicken, hedge-hog, guinea-pig, or rabbit. Renaut ('99) says 

 there are anastomoses at the periphery of the lobule in l)irds, not 

 in the human. My specimens show no anastomoses in the adult 

 pig, but perhaps ink-injections should not be accepted as conclu- 

 sive evidence upon this point. The question is of interest in con- 

 nection with the embryonic stages to be described below^ 



The ducts can be numbered and listed, upon the basis of the 

 foregoing description, as follows: (1) Main duct of the pancreas 

 (Santorini); (2) the laterals and their branches; (3) ducts to 

 lobule-groups, about 1000, all told; (4) unit-ducts, about 20,000 

 to 30,000; (5) the straight ducts; (6) pre-acinar ducts; (7) the 

 acini. But names and numbers mean nothing except so far as 

 they relate the \-essels to the subdivisions of the gland. 



I have already pointed out that there is no parallelism between 

 the artery and duct in the embryo (,fig. 2). Yet even though the 

 two vessels enter directly opposite sides of the embryonic lobule, 

 by the time that same lobule has grown to be an extensive tree 



THK AMERICAN JOURNAL OF ANATOMY, VOL. 16, NO. 2 



