摘要:

AbstractThe meninges of various mammals were prepared for examination with the electronmicroscope by thin sectioning or freeze‐fracturing. Particular attention was given to the distribution of tight junctions in order to determine the basis for the meningeal barrier between the blood circulating in dural vessels and the cerebrospinal fluid in the subarachnoid space. While some dural blood vessels are fenestrated, those in the subarachnoid space are not and their component endothelial cells are joined by an extensive system of tight junctions. An extensive and continuous system of tight junctions was also found in a layer of specialized cells at the border of the arachnoid with the dura. Thisarachnoid barrier layeris apparently the only basis of the meningeal barrier because often cellular layers in the dura and arachnoid lack tight junctions although they are linked by gap junctions and desmosomes. In particular, tight junctions are lacking at the border of the “subdural space” which is actually a fascial plane within the dura. Tight junctions are also lacking between astrocytes at the surface of the brain but these cells are linked by gap junctions and a new type of intercellular junction. The distribution of these junctions, as well as assemblies of intramembranous particles at the astrocytic border, raises the question whether this layer might have a role in the exchange of certain substances between the brain and cerebrospinal

ISSN:0092-7317    

DOI:10.1002/cne.901640202

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe organization of the brainstem serotonin neuron projection to the hippocampal formation was analyzed in the rat. This projection arises in the raphe nuclei of the midbrain. Following destruction of the midbrain raphe nuclei, chiefly nucleus centralis superior, there is a 72% decrease in hippocampal serotonin content. Injection of tritiated amino acid into the midbrain raphe nuclei results in transport of tritiated protein to the hippocampal formation and this transport is blocked in animals pretreated by intraventricular administration of 5,6‐dihydroxytryptamine (5,6‐DHT). Autoradiographic analysis indicates that the transport reaches the hippocampal formation primarily via two major pathways, the cingulum and the fornix. Cingulum fibers terminate predominantly in the dorsal hippocampus whereas the fornix distributes throughout the entire hippocampal formation. Some fibers reach the ventral hippocampus from the entorhinal area. Within the hippocampus there is dense labeling in a restricted lamina of the CA1 stratum lacunosum‐moleculare with moderate labeling in stratum radiatum. Stratum oriens is sparsely labeled in CA1 and moderately so in CA2 and CA3. Stratum radiatum and stratum lacunosum‐moleculare are moderately densely labeled in CA2 and CA3. The area dentata is sparsely to moderately labeled in the molecular layer and heavily labeled in a thin lamina of the hilar zone immediately beneath the granule cell layer. The remaining hilar zone is moderately labeled. All of the discrete labeling of the hippocampus and area dentata described above is absent in animals pretreated with 5,6‐DHT. These observations indicate that serotonin neurons of the midbrain raphe provide a highly organized innervation of the hippocampal formation i

ISSN:0092-7317    

DOI:10.1002/cne.901640203

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe inferior colliculus of the squirrel monkey is made up of a large central nucleus, bordered by the smaller external and pericentral nuclei. The majority of cells in the central nucleus exhibit a pronounced laminar arrangement due to the orientation of their dendrites. In medial sections of the nucleus these laminae lie in a dorsorostral to ventrocaudal direction. More laterally the layers assume a horizontal orientation and at the far lateral edge of the central nucleus come to lie in a ventrorostral to dorsocaudal orientation.A single tonotopic representation of audible frequencies is present in the central nucleus. A regular progression of best frequencies from low to high is encountered as a microelectrode advances from dorsocaudal to ventrorostral in the sagittal plane. Penetrations in more medial regions of the central nucleus encounter neurons whose best frequencies represent a higher range of frequencies than those in the lateral parts. The orientation of the isofrequency laminae determined physiologically appears congruent with the orientation of the dendritic laminae.The relative volume of the central nucleus devoted to each octave from 250 Hz to 32 kHz was determined. Frequencies up to eight kHz command successively larger amounts of collicular tissue. The octave band from 8 to 16 kHz is represented by the greatest amount of collicular tissue. Disproportionate representation of frequency may be the consequence of innervation density along the basilar membrane.

ISSN:0092-7317    

DOI:10.1002/cne.901640204

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

年代:1975

数据来源: WILEY

摘要:

AbstractHistochemical evidence is presented for a catecholamine‐containing projection from the nucleus locus coeruleus to the neocortex in the squirrel monkey. The innervation of superior temporal gyrus has been examined in particular. Glyoxylic acid‐induced fluorescence shows an extensive arborization of fine, catecholamine‐containing fibers with prominent varicosities in all layers of the neocortex. The nucleus locus coeruleus is identified as a source of these fibers by both ortho‐ and retrograde axonal tracing techniques. After injection of horseradish peroxidase into the neocortex, labelled cell bodies are localized throughout the major portions of the locus coeruleus. Conversely, after microinjection into the nucleus locus coeruleus, tritiated proline is transported into the neocortex where it appears within fibers similar in distribution to those revealed by fluorescence histochemistry. Both transport techniques indicate that cortical projections of the locus coeruleus originate from both ipsilateral and contralateral

ISSN:0092-7317    

DOI:10.1002/cne.901640205

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

年代:1975

数据来源: WILEY

摘要:

AbstractInterhemispheric neocortical connections are widely distributed through the corpus callosum in the mouse. Callosal connections are present in all cytoarchitectonic fields except field 25. The distal extremity representations of SmI, and MsI the representation of the mystacial vibrissae in SmI, and the more peripheral field representation of VI are relatively acallosal. Dense projections lie in the midline or truncal representations of SmI, MsI, SmII, at the vertical meridian representations bordering field 17, and medial to the AI representation. The radial distribution of terminals is bimodal in most cytoarchitectonic fields. It is unimodal in the supracallosal segment of field 29b and fields 49 and 27, trimodal in fields 13 and 35.The cells of origin of callosal fibers appear to have the same topographic pattern of distribution as the callosal terminals, observing the same steep and gradual density gradients. No cells giving rise to callosal axons are identified in the acallosal regions of fields 2 and 17. Further, superficial focal lesions in cortical areas which receive callosal connections give rise only to homotopic contralateral degeneration. Acallosal areas of 17 and 2 give rise to no callosal connections. The cells of origin of callosal connections are located at all laminar levels of the cortex and include pyramidal and polymorphic cells but not the granule cells of layer IV.

ISSN:0092-7317    

DOI:10.1002/cne.901640206

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe neocortex of the normal mouse has been subdivided into architectonic fields on the basis of its cellular and fiber patterns. The map of medial, retrohippocampal, frontal and insular regions is little different from that of Brodmann as modified in minor ways by Krieg. The map of parietal, occipital and temporal regions follows closely the major rearrangements introduced to Brodmann's map by Krieg. Krieg's map has been modified to give individual status to the barrel fields and to designate occipital fields around the full circumference of field 17, and temporal fields circumferentially around field 41.

ISSN:0092-7317    

DOI:10.1002/cne.901640207

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

年代:1975

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901640201

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

年代:1975

数据来源: WILEY