The nerves which enter the pancreas include sympathetic, parasympathetic and afferent components. The sympathetic preganglionic fibers traverse the splanchnic nerves ; the parasympathetic preganglionic fibers traverse the vagi. Preganglionic fibers effect synaptic connections in the celiac ganglia and in small ganglia within the pancreas. Nerve plexuses exist around the pancreatic blood vessels, the acinar cells and the cells within the pancreatic islets. The exact relationships of these fibers to the celiac ganglia and their distribution within the gland proper are not fully understood. Physiologic investigation has supplied many clues in this regard, but the opinions of various investigators conflict. While splanchnic and vagal stimulation produce noticeable secretory effects, it is impossible, without complete anatomic data, to determine whether these effects are due to the action of secretory fibers or merely to vasomotor changes. By means of nerve degeneration experiments the author has attempted to analyze the components of the pancreatic nerves more accurately than has been possible without such experimental procedure.
REVIEW O F THE LITERATURE
Ramdn y Cajal and Sala (1891) described nerve terminations between the acinar cells and small "corpusculos ganglionare simpaticos viscerales" in the parenchyma of the gland. Miiller (1892) recognized a double origin for the nerve fibers terminating within the pancreas. Some, he said, are branches of the characteristic ganglion cells within the gland, and many enter the gland as nerve bundles. The nerves pass in part to blood vessels. The remainder are distributed to the acini and the excretory ducts of the gland. Pensa ('05) illustrated nerve plexuses in the pancreatic islets and on the acinar. cells but found no ganglion cells within the gland. Ssobolew ( 'la), Briigsch et al. ( '21), van Campenhout ( '25, '27), Simard ( '35, '37, '42) and Alipio-Lob0 '42) found ganglion cells but limited their study to these structures. The only intensive discussions of the nerve terminations in the pan-
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