摘要:

AbstractThe pre‐ and postnatal development of trigeminal calcitonin‐gene‐related peptide (CGRP)‐ and sympathetic norepinephrine (NE)‐containing nerves supplying the cerebral arteries was studied with immunohistochemistry in rats. At 18–19 days in utero (E 18–19), CGRP fibers were present only as one or two longitudinal bundles zigzagging along the anterior cerebral artery and anterior communicating artery. Growth‐cone‐like swellings were found at the terminals of individual fibers. In contrast, at this same prenatal age NE fibers were present as a meshwork on all cerebral arteries. The density of NE fibers was higher in the rostral than in the caudal parts of the circle of Willis; growth cones were present on individual fibers at the middle segment of the basilar artery and distal parts of major cerebral arteries. At postnatal day 1–2 (PND 1–2; date of birth = PND 1), the outgrowth of CGRP axons extended along the walls of the middle cerebral and internal carotid arteries. These axons were relatively straight and unbranched. At the same time, NE fibers increased in number and density and continued to form the meshwork pattern on all cerebral arteries. At the end of the first postnatal week, all the longitudinal NE bundles on the rostral part of the circle of Willis began to form circular arborizations. At the end of the second postnatal week, the pattern of NE innervation had completely changed, consisting almost entirely of circumferential rather than tangential fibers. Beginning in the first postnatal week, CGRP fibers increased greatly in number and density and began to form a meshwork pattern. At the second postnatal week, the pattern of CGRP innervation, compared to the pattern at fetal and neonatal stages, had changed significantly, consisting predominantly of a meshwork pattern. By 4 weeks after birth, both the NE and CGRP fiber systems achieved adult densities and patterns.The present results demonstrate the following: (1) Both sympathetic‐NE and trigeminal‐CGRP innervation of cerebral arteries begin in utero; the NE system innervates corresponding parts of the vessels earlier than the CGRP system. (2) Both NE and CGRP fibers are more dense in the rostral than in the caudal segments of the circle of Willis; this rostrocaudal gradient is expressed in both density and pattern by the earliest fibers of both neurochemical systems and is maintained throughout all developmental stages. (3) The mature pattern of trigeminal CGRP fibers is a meshwork; the mature pattern of the sympathetic NE fibers is circumferential; both of these fiber systems undergo developmental reorganization to achieve adult innervation patterns in the second postnatal week. At this point in time, NE fibers rapidly transform from a meshwork pattern, similar to the mature pattern of trigeminal CGRP fibers, to an entirely circumferential pattern in only 1 week. The events which regulate this dramatic transformation are unknown. As there are no abrupt changes in vessel diameter during this period, mechanical factors probably do not play a decisive role. Factors which may be important include the central innervation of ganglionic neurons, competition for vascular synaptic sites, neurotrophic signals, or modifications in the struc

ISSN:0092-7317    

DOI:10.1002/cne.902790102

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe localization and structure of intercellular junctions and barriers in the extragemmal epithelium of canine fungiform papillae were determined by using both morphological and electrophysiological methods. Gap junctions were located in all epithelial strata with the exception of the stratum corneum, suggesting that the epithelium functions as a syncytium. The extracellular space of the stratum corneum was composed of a discontinuous, three‐dimensional network of tight junctions, modified desmosomes, and lamellar bodies. A zonula occludens, which stops the penetration of lanthanum, is present in the uppermost layer of the stratum granulosum. In freeze‐fracture replicas, tight junctions appear as extended networks of ridges of variable thickness on the PF fracture face and complementary grooves on the EF fracture face. The relatively high resistance pathway resulting from the layers of corneocytes and networks of tight junctions and lamellar bodies in the stratum corneum is bypassed by the low‐resistance pathway provided by the taste

ISSN:0092-7317    

DOI:10.1002/cne.902790103

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractStructures and connections of auditory forebrain regions of the Northern native cat, a member of one of the most primitive families among Australian marsupials, have been examined anatomically by using anterograde and retrograde tracing techniques with wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) after defining the acoustically responsive neocortical area physiologically.The structure of the medial geniculate body (MG) was similar to that described in other species. The results obtained from a case with a WGA‐HRP injection into the MG showed that the MG strongly projects to the lateral amygdaloid nucleus (LAmy) and the putamen as well as the auditory neocortex (ACx). Results obtained from other cases with WGA‐HRP injections into the physiologically defined ACx show also that the ACx is connected not only with the ipsilateral MG and the contralateral ACx but also with the LAmy both bilaterally and reciprocally. The regions within the LAmy in which the MG‐LAmy projection fibers terminate largely overlap with those in which the ACx‐LAmy fibers terminate and the LAmy‐ACx pathway originates.The connectional relationships revealed in the present study‐that the LAmy receives auditory information from the MG and reciprocates auditory information with the ACx bilaterally‐strongly suggest that, in some primitive mammals with small neocortical areas, a specific portion of noncortical telencephalon functions as an auditory center and occupies a relatively large volume of space in the forebrain. It is possible that the auditory sector of noncortical telencephalon in some primitive mammals such as the American Didelphidae and the Australian Dasyuridae is homologous with part of the auditory sector of the dorsal ventricular ridge (DVR) in reptiles and birds and also may have functions shared with the auditory primary and association neocortex in advanced mammals such as the domestic cat and the monkey (K

ISSN:0092-7317    

DOI:10.1002/cne.902790104

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractSemithin sections of the cat retina were stained with antibodies against GABA conjugated to bovine serum albumin with glutaraldehyde. Labelled cells were visualized by means of the peroxidase‐antiperoxidase method. In the outer plexiform layer both A‐ and B‐type horizontal cells and the B‐type axon terminal system expressed GABA‐like immunoreactivity. Approximately 25–30% of all amacrine cells and the whole inner plexiform layer were heavily labelled. Two types of putative GABA‐ergic interplexiform cells could be distinguished. One of them also expressed tyrosine‐hydroxylase‐like immunoreactivity. A few bipolar cells were also GABA‐immunolabelled. GABA‐like immunoreactivity and3H‐muscimol uptake were colocalized in 90% of the amacrine cells labelled. However, horizontal cells did no

ISSN:0092-7317    

DOI:10.1002/cne.902790105

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe synaptic organization of the cat retina was studied with antibodies against the GABA‐GA (glutaraldehyde)‐BSA (bovine serum albumin) complex. The postembedding technique combined with immunogold labelling ensured ultrastructural preservation and made identification of synapses possible. The most common putative GABA‐ergic synapses in the inner plexiform layer were amacrine‐to‐bipolar‐cell synapses followed by amacrine‐to‐ganglion‐cell and amacrine‐to‐amacrine‐cell synapses. GABA‐immunoreactive amacrine cells received most of their synaptic input from bipolar cells followed by other amacrine cells. Synapses between two labelled amacrine cells were common. Rod bipolar cells were the predominant input source and also the preferred output target of GABA‐labelled amacrine cells. OFF‐ and ON‐ganglion cells received putative GABA‐ergic synapses at their dendrites in laminas a and b, respectively, and also at their somata.In the outer plexiform layer, synapses of interplexiform cells onto bipolar cell dendrites expressed GABA‐like immunoreactivity. In both the cone pedicles and the rod spherules, GABA‐like immunoreactivity was

ISSN:0092-7317    

DOI:10.1002/cne.902790106

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe differential distribution of serotonin (5HT) fibers in spinal laminae VII and X is described for the adult rat. The results indicate that descending 5HT fibers preferentially innervate those regions of lamina VII that contain sympathetic and parasympathetic neurons. In lamina X, especially the dorsal commissural nucleus, large numbers of 5HT fibers are observed throughout the spinal cord. Moreover, sympathetic nuclei are more richly innervated with 5HT than the spinal parasympathetic nuclei. Spinal cord hemisections reveal that spinal autonomic nuclei are differentially innervated: ipsilateral serotoninergic projections to the intermediolateral cell column are preferentially interrupted. In addition, a large crossed 5HT projection exists throughout the length of the spinal cord that decussates five to six spinal segments rostral to its termination. Both crossed and uncrossed 5HT fibers span many spinal segments and have large numbers of collaterals. Spinal cord transections show that the vast majority of spinal 5HT descends from the brainstem but that some 5HT fibers are of intrinsic origin.

ISSN:0092-7317    

DOI:10.1002/cne.902790107

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThese studies reveal that the postnatal ontogeny of serotonin (5HT) in the sympathetic nuclei of the rat spinal cord is protracted; the adult complement of 5HT‐immunoreactive fibers is not achieved until at least 60 days of age. As descending serotonin fibers innervate and demarcate the distribution of preganglionic sympathetic nuclei, rostral‐caudal and temporal gradients exist. Additionally, a heterogeneous segmental 5HT ontogenetic pattern is observed in sympathetic nuclei. Most serotonin fibers in laminae VII and X are unorganized at birth except for some sympathetic nuclei in high thoracic regions where the 5HT sympathetic pattern is being initiated. By postnatal day 6 the framework of the 5HT pattern is established in all sympathetic nuclei, and by postnatal day 16 a pattern is formed, which develops into the compact adult state by postnatal day 60. The protracted period of sympathetic 5HT development corresponds with the length of time it takes for the autonomic nervous system to mature. In addition, 5HT intraspinal cell bodies are observed at all time points examined, except for the day of birth, and are found in the same regions as adult 5HT neurons, i.e., dorsal or lateral to the central canal in laminae VII and X and in all spinal segments except cervical levels. Many of the 5HT neurons are pericanalicular and bipolar in appearance. Multipolar 5HT neurons are first observed on postnatal day

ISSN:0092-7317    

DOI:10.1002/cne.902790108

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractImmunohistochemical methods were used to study the distribution of SP‐like immunoreactivity (SPLI) in the brain of the common goldfish (Carassius auratus). SPLI cell bodies and fibers were seen in distant areas and nuclei throughout the brain. In the telencephalon, SPL1 was found in the area dorsalis telencephali pars centralis and pars lateralis, areas that have been compared to the basal ganglia of land vertebrates. In the diencephalon, SPLI somata were seen in the hypothalamus. Four primary visual centers contained SPLI fibers: the nucleus of the posterior commissure, the area pretectalis, the nucleus dorsolateralis thalami and the optic tectum; the origin of these fibers could not be determined. SPLI cell bodies were seen in the oculomotor nucelus; the possibility that this may be the Edinger‐Westphal nucleus is discussed. A high density of immunoreactive fibers was seen in the tractus retroflexus and the interpeduncular nucleus, though the habenula showed a few SP‐like immunopositive fibers. In the hindbrain, SPLI cell bodies and fibers were seen in the nuclei ambiguus and commissuralis of Cajal and in the dorsal motornucleus of the vagus nuclei; even though these nuclei are known to belong to the visceral and sensory motor columns, the exact role SP plays in processing this information is at present un

ISSN:0092-7317    

DOI:10.1002/cne.902790109

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe periodontal ligament is richly innervated by mechanoreceptors whose cell bodies are located either in the trigeminal ganglion (TG) or the mesencephalic (MS) trigeminal nucleus. Both are sensitive to stretch of the ligament induced by tooth movement, but their thresholds, central connections, and functional significance differ. This study compared the location of TG and MS receptors in the periodontal ligament of cat teeth after labeling each by anterograde axonal transport. We also compared the location and ultrastructure of the feline TG receptors with labeled TG receptors in the periodontal ligament of monkey teeth and rat incisors in order to determine their location and ultrastructural properties.We found that the MS and TG receptors had a different distribution in the periodontal ligament of cat teeth; the MS terminals were concentrated below and next to the base of the roots, whereas the TG receptors were most numerous around the middle of the roots. The TG receptors of monkey teeth had a similar location to the feline TG receptors, but those of rat incisors were very different. Rat incisors are curved, continuously erupting teeth, and their TG receptors were located primarily on the lingual side in the alveolar (nonerupting) portion of the ligament. Ultrastructural comparisons found that most mechanoreceptors in the periodontal ligament of all the teeth had an unencapsulated branched Ruffini‐like structure. The TG receptors in the rat incisor ligament were the largest; those of monkey had the most varied form. Some coiled or encapsulated receptors were found in the monkey and cat ligament, but not in the rat incisor ligament. The TG receptors appear to be located at sites that would be most easily stretched during tooth contact. The different sites and intensity of the stretch forces occurring during the use of different types of teeth may determine the variations in the size and location of the TG mechanoreceptors and of their associated support cells. The different distribution of MS receptors may contribute to their response thresholds and static properties, which differ from those of TG receptor

ISSN:0092-7317    

DOI:10.1002/cne.902790110

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractSeveral lines of anatomical, biochemical, and pharmacological evidence have suggested that specific high affinity neurotensin binding sites are associated with dopamine‐containing neurons in the rat ventral tegmentum. In the present study we confirmed and quantified the extent of this association by combining monoiodinated neurotensin radioautography and tyrosine hydroxylase immunohistochemistry on adjacent 5–10μm‐thick midbrain sections. We found that 95–100% tyrosine hydroxylase‐immunoreactive neurons detected in all subdivisions of the substantia nigra (pars compacta, pars lateralis, and pars reticulata) exhibited intense125I‐neurotensin labeling in adjacent light microscopic radioautographs. Tyrosine hydroxylase‐positive dendrites radiating downward from compacta neurons were also heavily labeled throughout the pars reticulata. In the paranigral subdivision of the ventral tegmental area, silver grains were evenly distributed over neuropil and perikarya and therefore could not be readily attributed to any given tyrosine hydroxylase‐positive element. In contrast, within the parabrachial pigmentous subdivision of the ventral tegmental area, 80–90% of the tyrosine hydroxylase‐immunoreactive somata and proximal processes were clearly in register with125I‐neurotensin labeled cells. Finally, all tightly packed TH‐positive neurons in the interfascicular nucleus showed intense125I‐neurotensin labeling. The vast majority of the neurotensin binding sites observed in the ventral midbrain tegmentum were of the high affinity, physiologically active receptor type since levocabastine, a selective blocker of the low affinity neurotensin binding component, had minimal effect on the binding density in any of the midbrain regions examined. The present results demonstrate an extensive overlap between specific, high affinity neurotensin binding sites and dopamine perikarya and dendrites in the rat ventral tegmentum, and thereby provide a direct anatomical substrate for observed neurotensin‐dopamine interactions in the mesocorticolimbic and nigr

ISSN:0092-7317    

DOI:10.1002/cne.902790111

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY