摘要:

AbstractThe fine structural organization of the principal sensory trigeminal nucleus was compared with that of the spinal trigeminal nucleus (subnuclei oralis, interpolaris, and the deep layers of caudalis) in adult albino rats. Direct comparisons indicate similarities between all of the subdivisions of the brainstem trigeminal complex both in the major morphological classes of neurons present and in basic patterns of synaptic connections. Major differences between the several subdivisions occur in the relative numbers and distribution of the different cell types.The spinal trigeminal nucleus is distinguished by more numerous large (22–40 μm) polygonal neurons which give rise to long straight primary dendrites. Both the perikaryal surface and the thick primary dendrites of many of these cells are densely innervated by synaptic terminals. Especially large cells of this type are a prominent feature of subnucleus oralis. By contrast, the principal sensory nucleus is distinguished by its high density of small to medium‐sized (8–20 μm) round or ovoid neurons. These smaller neurons tend to receive a sparse axosomatic innervation. In addition to these differences the spinal trigeminal neuropil is distinguished by the striking manner in which it is broken up by large rostrocaudally oriented bundles of myelinated axons. Proximal dendrites of polygonal and fusiform neurons often wrap around these large axon bundles.Morphologically heterogeneous populations of synaptic terminals with round vesicles (R terminals) and terminals with predominantly flattened vesicles (F terminals) occur in all of the subdivisions of the trigeminal complex. Both types of terminal make primarily axodendritic synapses, but both also make axosomatic synapses, and axospinous synapses with somatic as well as dendritic spines. In addition, axoaxonic synaptic contacts from F terminals onto large R terminals are seen in all subdivisions. Convincing examples of presynaptic dendrites were not observed in any of the brainstem subdivisions.Synaptic glomeruli, characteristic groupings of dendrites and synaptic terminals, are found throughout the brainstem trigeminal complex. The dendritic elements in these glomeruli tend to be small‐diameter dendrites, spines, and large, spinelike appendages. Within the glomerulus these elements are postsynaptic to a single large R terminal and may also be postsynaptic to smaller F terminals. In addition, axoaxonic synaptic contacts from the F terminals onto the R terminal are a consistent feature of trigeminal synaptic glomeruli. Serial reconstructions of glomeruli indicate that both the R and the F terminals commonly occur as boutons en passant, with single axons innervating multiple glomeruli. Within the trigeminal complex synaptic glomeruli are often grouped together into clusters, which we have termed “glomerular nests.” We suggest that the peripherally related afferent segmentation characteristic of the rat's brainstem trigeminal complex is reflected in the distribution o

ISSN:0092-7317    

DOI:10.1002/cne.902350202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe regions projecting to Gudden's tegmental nuclei were examined by retrograde transport of horseradish peroxidase or wheat‐germ‐agglutinin‐conjugated horseradish peroxidase. Gudden's tegmental nuclei in the rabbit can be divided into a pars principalis of the ventral tegmental nucleus (TVP), a pars ventralis of the dorsal tegmental nucleus (TDV), and a pars dorsalis of the dorsal tegmental nucleus (TDD).The TVP receives many fibers from the medial division of the ipsilateral medial mammillary nucleus and bilaterally from the lateral habenular nucleus, and additionally some fibers from the posterior nucleus of the interpeduncular complex. The TDV receives many fibers from the ipsilateral lateral mammillary nucleus, from the ipsilateral prepositus hypoglossi nucleus, bilaterally from the lateral habenular nucleus, from the central and paramedian nuclei of the interpeduncular complex, from the bilateral gray matter along the floor of the fourth ventricle, and from the contralateral supragenual nucleus. The TDD receives a projection from the lateral habenular nucleus of both sides and from the central and paramedian nuclei of the interpeduncular complex, and a minor projection from the ipsilateral lateral mammillary nucleus, the posterior nucleus of the interpeduncular complex, the prepositus hypoglossi nucleus, and the contralateral supragenual nu

ISSN:0092-7317    

DOI:10.1002/cne.902350203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThis experiment analyzed the organization of the rat abdominal vagus. To spare delicate tissues and preserve positional information, untrimmed blocks of the subdiaphragmatic viscera (N = 22) were fixed, impregnated by using a pyridine‐silver protocol, and double embedded. Each block was sectioned transversely at 7 μm, and a section every 70 μm from the diaphragm to the cardia was analyzed. The features of the section were traced and digitized for computer reconstruction. Included in the measurements were sizes and locations of bundles, fascicles, and paraganglia.The anterior and posterior vagi were consistently distinctive in size, distribution, cross‐sectional shape, and paraganglionic content. In the most common pattern (41% of animals), the anterior trunk coursed longitudinally on the ventral surface of the esophagus, giving off at successively more distal levels the hepatic branch, the accessory coeliac branch and then the bundles of the anterior gastric branch. The posterior trunk separated into a coeliac branch and a posterior gastric branch, each consisting of numerous bundles, in the most distal quarter of the esophagus. Fifty‐nine percent of all animals exhibited one or more significant variations in vagal organization (e.g., double primary trunks—41%, supernumerary branches—18%, or atypical branching sequences—9%).Four to 14 vagal paraganglia (mean = 8 ± 1; equivalent to 32/rat, corrected for sampling) were found in each animal, and no branch was consistently devoid of paraganglia. Ninety‐four percent of the paraganglia were located at nerve branch points. Some of the larger paraganglia contained at their central poles one to six neurons with soma diameters ranging

ISSN:0092-7317    

DOI:10.1002/cne.902350204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe retinal terminal zones and the morphology of relay neurons within the dorsal lateral geniculate nucleus (LGNd) of the brush‐tailed possum (Trichosurus vulpecula) have been investigated with horseradish peroxidase (HRP) tracing techniques. Anterograde transport of HRP from the retina confirmed previous descriptions of the laminar distribution of retinal afferents in this nucleus. In addition, it was found that lamina III consists of two adjacent bands (IIIa and IIIb) of contralateral retinal input, separated by a terminal‐free zone 20–40 μm wide. This zone is not apparent with Nissl or fibre stains.Relay neurons in the LGNd were retrogradely filled following cortical injections of HRP, and two classes (A and B) were distinguished. Class A neurons are found in the alpha portion of the LGNd (laminae I, II, III, and IV) and class B neurons in the beta portion (laminae V, VI, and VII). Class A cells are more densely packed and have shorter and more numerous dendrites, less‐extensive dendritic arbors, and thicker axons than class B cells. No significant differences were found between the two classes in perikaryal size or thickness of proximal dendrites. Neurons in each lamina of the nucleus have dendritic arbors which ramify extensively within adjacent laminae, except cells in lamina IIIb, which have relatively few dendrites that cross into the cell‐free zone and

ISSN:0092-7317    

DOI:10.1002/cne.902350205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe dorsal torus semicircularis (torus) of the gymnotiform fishEigenmanniawas examined in Golgi impregnated material. These results were correlated with those of a previous HRP study which used retrograde labelling techniques to identify the efferent cell types of the torus (Carr et al., '81, J. Comp Neurol.203: 649–670).The torus is a laminated midbrain nucleus of the electrosensory system. It receives somatotopically ordered electrosensory input from the medulla and caudal lobe of the cerebellum, proprioceptive input from the descending nucleus of the trigeminal nerve, and input from the optic tectum. The torus projects to the nucleus praeeminentialis, the optic tectum, nucleus electrosensorius, parts of the central posterior thalamus, the pretectum, the lateral mesencephalic reticular formation (LMRA), the reticular formation, and the inferior olive.The torus has 12 laminae and 48 cell types by Golgi criteria. There are three major orientations to the dendritic fields of the toral neurons: (1) purely horizontal neurons with dendrites confined to a single lamina, (2) multipolar neurons whose dendrites often do not respect laminar boundaries, and (3) vertical cells with dendrites that travel in the vertical bundles of dendrites and axons which pierce the torus at regular intervals.There are four major groups of vertically oriented neurons. The first has a predominantly horizontal dendritic tree with one or two vertical dendrites which connect the cell to a distant lamina. The second consists of “U”‐shaped neurons with a horizontal arbor and two major dendrites which ascend in adjacent vertical bundles. The third group is made up of bilaminar neurons which receive input from two vertically separated dendritic arbors, and the fourth group is purely vertical in orientation. A group of four tegmental cell types in the LMRA also send their dendrites into the efferent tracts of the torus, and into lamina IX.The torus is similar in complexity and number of cell types to the mammalian inferior colliculus. The large number of cell types in these midbrain sensory nuclei, compared to the number of afferent inputs (seven or more for the torus) is notable and may reflect the parcellation of function associated with the parallel processing of these

ISSN:0092-7317    

DOI:10.1002/cne.902350206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractParietotectal projections were studied in the macaque monkey in experiments designed to compare the distribution of fibers originating in two cytoarchitecturally distinct regions within the inferior parietal lobule: the inferior bank of the intraparietal sulcus (area POa of Seltzer and Pandya, '80) and the adjoining part of area PG (von Bonin and Bailey, '47) on the convexity of the hemisphere, here called PGc. A dense fiber projection from POa to the intermediate and deep layers of the superior colliculus was observed by both anterograde autoradiographic and anterograde horseradish peroxidase methods. In contrast, only faint labeling was seen in the superior colliculus following injections of tritiated amino acids into area PGc on the convexity. In a second set of experiments, injections of horseradish peroxidase were placed in the intermediate and deep layers of the superior colliculus so that the cells of origin of the parietotectal projections could be identified. Many retrogradely labeled neurons were observed in POa, whereas very few labeled neurons were present in any other subdivision of the inferior parietal lobule or in the superior parietal lobule. These findings demonstrate that area POa has a prominent direct efferent projection to a major premotor region of the brainstem oculomotor system and suggest that by virtue of its parietotectal connection, this sulcal subdivision may have functional properties not shared with other subdivisions of the inferior parietal lobule.

ISSN:0092-7317    

DOI:10.1002/cne.902350207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe spatial and size distributions of motoneurons which supply the cat lateral gastrocnemius (LG) neuromuscular compartments were examined to determine their anatomical organization. Individual primary muscle nerve branches (PMNB) to LG were isolated by microdissection, cut, and soaked in horseradish peroxidase (HRP). As a control in each case, the entire contralateral lateral gastrocnemius‐soleus (LG‐S) nerve was similarly cut and soaked. Retrogradely labeled motoneurons were identified, their positions plotted, and their sizes measured on both sides of the cord. Results show that extensive overlap exists in the spatial distribution of motoneurons innervating different PMNBs. Labeled cells supplying each PMNB also vary considerably in their sizes. However, both a highly significant topography‐like organization and a preferential size distribution are found between different groups of motoneurons. Neurons which supply proximal compartments occupy more rostral portions of the LG motor nucleus and are among the largest in the pool. Very few small motoneurons innervate proximal compartments. Neurons supplying more distal compartments are distributed in more caudal parts of the pool and contain both large and small cells in relatively equal numbers. If the large cells are alpha and the small cells gamma motoneurons, then proximal compartments are relatively poor in gamma innervation and presumably muscle spindles, and distal compartments are rich in fusimotor innerv

ISSN:0092-7317    

DOI:10.1002/cne.902350208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThis study shows (1) the ultrastructure of vasoactive intestinal polypeptide (VIP)‐, substance P (SP)‐, and neuropeptide Y (NPY)‐containing nerve fibers in the walls of the cerebral arteries and (2) the relationship between these peptidergic (VIP, SP, and NPY) and catecholaminergic (CA) nerve terminals by immunohistochemistry combined with false transmitter (5‐hydroxydopamine) histochemistry under the electron microscope. VIP‐, SP‐, and NPY‐like immunoreactivity (VIPI, SPI, and NPYI) were found diffusely in the axoplasm and around the small clear vesicles in the nerve terminals. In a few cases, SPI was found within the large vesicles. Most of the VIPI terminals were ensheathed by the cytoplasm of the Schwann cells together with CA terminals, identified as those with a number of small granulated vesicles. In some cases, they were directly apposed to the smooth muscle cells at a distance of about 100 nm. SPI terminals were frequently solitary but about 30% were located together with CA and other (neither SPI nor CA) terminals ensheathed by Schwann cells, directly apposed to the smooth muscle cells at a distance of about 100 nm. On the other hand, NPYI terminals were also identified as CA terminals, indicating the coexistence of these two substances. These findings suggest a close interrelationship between peptidergic and CA nerve terminals in the neurogenic control of cerebral blood ve

ISSN:0092-7317    

DOI:10.1002/cne.902350209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902350201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY