Endoscopic retrograde cholangiopancreatography in the management of pancreatic pseudocysts.

The value of ERCP was studied in 25 patients with pancreatic pseudocysts. There were no episodes of sepsis; however, acute pancreatitis developed in one patient for an overall complication rate of 4 percent. Results of ERCP were positive in 24 of the 25 patients (96 percent), with filling of the pseudocyst in 17 and pancreatic ductal obstruction in 7. Biliary tract abnormalities were found in seven patients and included common bile duct strictures in four, bile duct dilatation in two, and cystic duct obstruction in one. ERCP also detected six pseudocysts not diagnosed by ultrasonography, five of which were small and resolved with nonoperative therapy. ERCP is a safe diagnostic procedure for patients with pancreatic pseudocysts and may provide important information about coexistent biliary tract disease not otherwise available. It is also sufficiently sensitive to detect small pseudocysts that otherwise would be missed.

The formation and growth of the cortical layers in the cerebellum of the opossum.

The development of the cerebellar cortex in the opossum was analyzed in Nissl-stained sections using qualitative and quantitative methods. The young of the opossum are born 12-13 days after conception and mature for approximately 85 days in an external pouch providing an excellent model for embryological studies. Qualitative observations of cerebellar growth were made from birth to postnatal day (PN) 19. At birth the opossum cerebellar anlage can be divided into two layers, a ventricular layer and an intermediate layer; histologically his is comparable to the rat cerebellar anlage at embryonic day 13 (Altman and Bayer 1978) and the human cerebellar anlage prior to the seventh embryonic week (Rakic and Sidman 1970). By PN 3 the cerebellar anlage consists of five layers: the ventricular layer, the ventral intermediate layer, the acellular layer, the dorsal intermediate layer and the marginal layer. The external granular layer begins migrating over the dorsal surface of the cerebellum at PN 5. The immature Purkinje cell layer is first seen at PN 12 and is subsequently arranged as four clusters between PN 12 and PN 22. At PN 19 the opossum cerebellum is comparable to the rat cerebellum at birth (Korneliussen 1968c). A quantitative analysis of cerebellar growth was performed between PN 17 and PN 77 using vermal sections. The area and thickness of each of the cortical layers was determined from five vermal sagittal sections using two methods; a Zeiss Videoplan and a point counting system. The external granular layer increases in area from PN 17 to PN 75, however its maximal width is achieved between PN 19 and PN 33. The persistence of the EGL until after PN 105 suggests that synaptic contacts between granule cell axons and Purkinje cells may continue to form after PN 77 when the Purkinje cell is mature based on Golgi and fine structural features (Laxson and King 1983). Between PN 17 and PN 77 the area of the molecular layer and the area of the internal granular layer increase at a more rapid rate than the other cerebellar layers. The maturation of the cerebellum in the opossum is a lengthy process lasting approximately 77 days in comparison to rodent cerebellar growth which requires about 25 days (Korneliussen 1968c). Also, the entire process of cortical lamination occurs after birth while the opossum is maturing in an external pouch.

Spinal projections from the medullary reticular formation of the North American opossum: heterogeneity.

Retrograde and orthograde transport techniques show that the nucleus reticularis gigantocellularis pars ventralis and the nucleus reticularis gigantocellularis project the entire length of the spinal cord. Double-labelling methods show that some of the neurons in each area innervate both cervical and lumbar levels. There is evidence, however, that neurons in the lateral part of the nucleus reticularis gigantocellularis pars ventralis and the dorsal extreme of the nucleus reticularis gigantocellularis project mainly to cervical and thoracic levels. The autoradiographic method shows that the above nuclei supply direct innervation to somatic and autonomic motor columns as well as to laminae V-VIII and X. The nucleus reticularis gigantocellularis pars ventralis provides additional projections to lamina I and the outer part of lamina II. Several areas of the medullary reticular formation project mainly, and in some cases exclusively, to cervical and thoracic levels. These areas include the nucleus reticularis parvocellularis, the nucleus reticularis lateralis, the nucleus retrofacialis, the nucleus ambiguus, the nucleus lateralis reticularis, caudal parts of the nuclei reticularis medullae oblongatae dorsalis and ventralis, and the nucleus supraspinalis. Autoradiographic experiments reveal that neurons in the ventrolateral medulla, particularly rostrally (the nucleus reticularis lateralis and neurons related to the nucleus lateralis reticularis), innervate sympathetic nuclei. Our results indicate that spinal projections from bulbar areas of the reticular formation are more complicated than previously supposed. Axons from separate areas project to different spinal levels and in some cases to different nuclear targets. These data are in conformity with the evolving concept of reticular heterogeneity.

Spinal projections from the mesencephalic and pontine reticular formation in the North American Opossum: a study using axonal transport techniques.

The results from several experimental approaches lead to the following conclusions. The nucleus cuneiformis projects to at least lumbar levels of the spinal cord. Its axons course through the ipsilateral sulcomarginal and ventral funiculi to distribute within lamina VIII and adjacent portions of lamina VII. Neurons within the nucleus reticularis pontis (RP), particularly within more medial parts of the nucleus, project through comparable routes to the same laminae. In addition, however, neurons within the lateral and dorsolateral RP relay through the lateral and dorsolateral funiculi, ipsilaterally, and the dorsolateral funiculus, contralaterally. Axons could be traced from the dorsolateral tracts to laminae IV through VII, lamina X and, in some instances, to laminae I and II. Injections of the dorsolateral pons also label the intermediolateral cell column and an area presumed to be the sacral parasympathetic nucleus. Many of the neurons which contribute to the contralateral bundle are located adjacent to the ventral nucleus of the lateral lemniscus. The nucleus reticularis gigantocellularis projects mainly via the sulcomarginal, ventral and lateral funiculi to laminae VIII and adjacent portions of lamina VII. The nucleus reticularis gigantocellularis pars ventralis innervates the same laminae; but, in addition, projects heavily to laminae I and II, to lateral portions of laminae IV through VII; to laminae IX and X and to the intermediolateral cell column. Axons destined for laminae I and II, as well as IV through VII and X, traverse the dorsolateral funiculi as described for the cat by Basbaum et al. ('78). Neurons within the nucleus reticularis parvocellularis project to cervical levels, mainly through the ventral funiculi. In general our results show that reticulospinal projections are more complex than suggested by degeneration methods and that laminae I, II. lateral parts of laminae IV-VII, laminae IX and X, as well as the intermediolateral cell column and sacral parasympathetic nucleus are targets of axons from specific areas.