At the present time, complete agreement on the origin and course of parasympathetic preganglionic fibers to the alimentary canal has not been reached. The purpose of this study was to trace vagal fibers to the abdominal cavity and to follow the distribution of these fibers to the digestive tube. The technique used was to label neurons in the dorsal motor nucleus of the vagus (DMX) with ³H-leucine and then to follow the orthograde transport. 16 albino rats were used in this experiment. The right DMX in one group of rats and the left DMX in the other group was injected with 25 μCi of ³H-leucine in three injections. The injection sites and tissue sections from various areas of the digestive tube were processed for autoradiography. A heavy label was observed in the injection site and it could be traced down the vagus nerve through the thorax into the abdomen. Labelled vagal fibers were found in the parasympathetic ganglia of the stomach, small intestine and colon.

Central organization of the cardiac vagus has not been clarified. Retrograde changes produced in medulla oblongata neurons after section of vagal branches has favored the dorsal motor nucleus of the vagus (DMNX). Current information concerning the origin, course, and termination of vagal preganglionic fibers within cardiac ganglia is conflicting. The explicit purpose of this study was to determine if vagal fibers originated specifically within the DMNX proper. Fibers within the cardiac ganglia were labelled with ³ H-leucine following injection into the DMNX. 12 adult albino rats were studied. DMNX were injected with 25 µCi ³H-leucine reconstituted to 5 µl. Animals were sacrificed by transcardial perfusion following a 4-day survival period. Serial cross-sections of the caudal pons, medulla oblongata, and thoracic viscera were processed for autoradiography. DMNX possessed a heavy incorporation of the radiochemical. Label was observed within the axons of the vagi. Cardiac ganglia contained labelled vagal fibers in close proximity to the postganglionic somata. Cardiac ganglia containing labelled preganglionic vagal axons were located in the cardiac plexuses and in the epicardium. Results show a labelled vagal preganglionic input to cardiac ganglia from the DMNX.

No abstract

Summary. Postganglionic sympathetic fibers originating in the celiac ganglion can be traced by autoradiography to the stomach, spleen, liver and pancreas.Autoradiography is a method widely used for tracing pathways in the CNS but its use in the peripheral nervous system has been more limited 1-5. Recently Kelts 6 has reported using this method to trace efferent fibers from the left celiac ganglion of cats to the contralateral celiac ganglion, satellite ganglia between the 2 celiac ganglia, and the adrenal gland. The present study followed the postganglionic sympathetic fibers originating in the left celiac ganglion of cats as they extended further to the stomach, spleen, liver and pancreas.Cats were anesthetized with Ketaset and a ventral midline incision was made in order to locate the ganglion. From 5 to 15 gl of tritium-labeled leucine (1 mCi/ml) was injected into the ganglion by means of a Hamilton syringe. Post injection periods from 48 to 98 h allowed for diffusion and anterograde axonal transport of the amino acid. The animals were then anesthetized and transcardially perfusedwith 10% buffered neutral formalin. A portion of the abdominal aorta containing the celiac trunk and the superior mesenteric artery with the celiac and superior mesenteric ganglia intact was removed. Branches of the celiac artery along with their accompanying nerves were traced to the organs studied. Sections of the celiac artery with its surrounding tissue were excised. Tissue from the region of the greater curvature of the stomach, from the superior pole of spleen, from the posterior lobe of the liver and from the omental area of the pancreas about 3 cm from the spleen was removed. All tissue was embedded in paraffin and serially sectioned, The sections were mounted on glass slides and dipped in Kodak NTB 2 emulsion. After a 3-week incubation period the sections were developed in D19 and fixed with Kodak Ektaflo. Ganglionic tissue was stained with 1% cresyl violet, the other tissue with hematoxylin and eosin. All slides were studied using light and darkfield optics. 498In all ganglia studied, 3H-leucine had infiltrated the neurons. Outlines of cell bodies could easily be seen due to dense concentrations of the silver grains ( fig. 1). This heavy labeling could readily be traced from the cell bodies into the nerves leaving the ganglia ( fig. 2). These large nerves branched repeatedly forming a plexus of smaller labeled nerves which accompanied small arteries ( fig. 3). This network of small nerves and blood vessels could be followed to the organs being studied. In addition small labeled nerves in close proximity to blood vessels were found within the stomach, spleen and pancreas ( fig.4). No apparent differences were observed between 48 and 98 h postinjection survival periods. This study demonstrates autoradiographically that nerve cell bodies in the celiac ganglion have postganglionic Summary, 12-O-tettadecanoyl phorbo1-13-acetate (TPA, 1-100 ng/ml) induced a reversible contraction in the hydra, Hydra japonica. Another tumor-promo...