摘要:

AbstractAxon counts were made at two standardised levels of C7 ventral spinal nerve roots from 46 female rats representing nine ages between birth and 500 days. The objective was to provide a definitive account of proximodistal changes in axon numbers and of age changes in axon numbers both during postnatal development and at several stages during maturity. At each age there is a proximodistal increase in the numbers of axons in all categories examined (myelinated, promyelin, transitional, and fetal) between levels midway along the subarachnoid course of the root and where it is apposed to but separate from the dorsal root ganglion.During maturation and throughout maturity axon totals change similarly at both levels: After a slight increase immediately postnatum, they decline sharply between 4 and 20 days due to a marked loss of unmyelinated axons. A gradual decline in myelinated axon numbers continues to 500 days. While these changes are occurring, axon numbers in all categories show a proximodistal increase throughout. The magnitude of this increase lessens with age for all but the transitional category due to a preferential decrease in numbers distally. Though these observations do not differentiate between axon branching and looping of sensory axons into the ventral root as a cause of the proximodistal increase in numbers, they tend to support the former.At each age during maturation axon proportions at proximal and distal levels correspond well for each animal, indicating that axon segregation proceeds at related rates within each root. Age changes in axon proportions within the transitional and fetal categories indicate that the postnatal stage of axon segregation results from axon loss, rather than Schwann cell proliferation.

ISSN:0092-7317    

DOI:10.1002/cne.902800202

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractTwo neuronal calcium‐binding proteins, calbindin‐D28k(CaBP) and parvalbumin (PV), were localized in the normal rat hippocampus by using immunocytochemical methods to determine (1) their location and (2) whether a correlation exists between the presence of these two calcium‐binding proteins and the selective vulnerability of different hippocampal neuronal populations to experimental seizure activity.CaBP‐like immunoreactivity (CaBP‐LI) is present in all dentate granule cells and some, but not all, CA1 and CA2 pyramidal cells. Some CA1 pyramidal cells lack CaBP‐LI, and those that do are lightly stained compared to the dentate granule cells. CA3 pyramidal cells appear to contain neither CaBP‐ nor PV‐LI, and no granule or pyramidal cells exhibit PV‐LI. CaBP‐LI is present in distinct populations of dentate and hippocampal interneurons but absent from others. In area dentata, CaBP‐LI is present in a small number of interneurons of the molecular and granule cell layers and in a small population of presumed basket cells in or below the granule cell layer. Conversely, more presumed dentate basket cells exhibit PV‐LI than CaBP‐LI. In the hilus of area dentata, few cells are CaBP‐ or PV‐immunoreactive. The hilar somatostatin/neuropeptide Y (NPY)‐immunoreactive cells and hilar mossy cells, two distinct and large populations, lack CaBP‐ and PV‐LI. In the CA3 region, CaBP‐LI is present in a relatively small number of interneurons in each stratum. PV‐immunoreactive interneurons in area CA3 are more numerous. In area CA1, CaBP‐LI is present in many interneurons in strata radiatum and lacunosum‐moleculare. Some, but relatively fewer, CaBP‐positive interneurons are present in strata pyramidale and oriens. Conversely, PV‐immunoreactive interneurons are numerous in strata pyramidale and oriens but rare in strata radiatum and lacunosummoleculare.Staining with the particulate chromagen benzidine hydrochloride revealed a previously undescribed dense band of CaBP‐LI in the inner dentate molecular layer, a lamina enriched with kainate‐displaceable glutamate‐binding sites and innervated by the apparently excitatory ipsilateral associational/commissural (IAC) pathway that originates in the CaBP‐negative hilar mossy cells. Bilateral electrical stimulation of the perforant path was performed in order to destroy the hilar mossy cells and to determine if this band of CaBP‐LI is normally present within the mossy cell terminals. Perforant path stimulation that destroyed hilar mossy cells throughout the dorsal portions of both hippocampi did not abolish the dense CaBP‐like immunoreactivity in the inner molecular layer.In summary, the cell populations visualized by immunocytochemical staining for CaBP‐ or PV‐LI are clearly distinct. All of the relatively seizure‐resistant dentate granule cells and many basket cells and hippocampal CA2 pyramidal cells are darkly stained for either CABP‐ or PV‐LI. The seizuresensitive dentate hilar somatostatin/NPY‐positive cells, hilar mossy cells, and hippocampal CA3 pyramidal cells appear devoid of both CaBP‐ and PV‐LI. The seizure sensitive CA1 pyramidal cells are devoid of PV‐LI and exhibit less CaBP‐LI than the seizure‐resistant granule cells. Therefore, a positive correlation exists between the presence of at least one of these calcium‐binding proteins in hippocampal neurons and their relative resistance to seizure‐induced neuronal damage.These data suggest that the relative vulnerability of different cell populations may be related to differences in the con

ISSN:0092-7317    

DOI:10.1002/cne.902800203

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn order to study the mechanisms of synaptogenesis in the rat cerebellar cortex, a library of monoclonal antibodies has been generated against proteins of the isolated synapse. One recognizes a glycosylated 38kDa protein that is concentrated in the synaptic vesicle fraction and resembles synaptophysin biochemically in its molecular weight, charge, and pattern of glycosylation. In the adult cerebellar cortex, the antisynaptophysin (mabQ155) immunoreactivity is codistributed with synapses. Immunoreactivity is strongest in the molecular layer where punctate deposits of reaction product outline the Purkinje cell dendrites. Discrete small profiles, consistent with the distribution of basket cell axon terminals, surround the Purkinje cells, and in the granular layer the synaptic glomeruli are intensely stained. There is no immunoreactivity in the white matter axon tracts. Electron microscope immunocytochemistry confirms the synaptic location of the antigen and suggests that the reaction product is associated with synaptic vesicles. Both round and flat vesicle populations are immunoreactive. Antisynaptophysin(mabQ155) has been used to follow synaptogenesis in the developing rat cerebellum. In the newborn rat (P0), despite the paucity of synapses, there is some specific immunoreactivity, especially in the subcortical white matter. Electron microscopy shows that the antigenicity is associated with vesicles within growth cones, filopodia, and immature axon profiles. During development, antisynaptophysin immunoreactivity increases progressively, along with the maturing cell populations, for both the granule cell‐Purkinje cell and the mossy fiber‐granule cell synapses. Quantitative biochemical analysis confirms the cytochemical results. These data suggest that neuronal growth cones express a synapse‐specific antigen before complete morphological synapses are pr

ISSN:0092-7317    

DOI:10.1002/cne.902800204

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe sexual dimorphism of the human corpus callosum (CC) is currently controversial, possibly because of difficulties in morphometric analysis. We have reinvestigated the issue by using morphometric techniques specially designed to yield objective measurements of CC size and shape. The development of the CC was studied with similar techniques in order to investigate whether its final shape and size might be influenced by axonal elimination, as could be expected from previous animal studies.We have measured the CCs of 32 men and 26 women; 27 male and 19 female CCs were from brain tissue, the others were from magnetic resonance imaging graphs. Women tended to have (1) a smaller cross‐sectional callosal area (CCA); (2) a larger fraction of CCA in the posterior fifth of the CC; (3) more slender CCs; and (4) more bulbous splenia. These differences could not be detected by simple inspection but were demonstrated by measurement and statistical analysis. However, CCA was correlated with the other sexually dimorphic parameters, and the sex‐related differences in the latter became nonsignificant when variations in CCA were factored out or when male and female populations with similar CCA were compared.In addition, we analyzed CCs of 16 male and 16 female fetuses and of 13 male and 15 female infants and children. This sample ranged in age between 20 weeks of gestation and 14 years but covered in detail the period up to 14 months after birth. CCA increased throughout the latter period but decreased slightly between about 33 weeks of gestation and the beginning of the second postnatal mouth. This decrease coincided with thinning of the CC and a marked increase in bulbosity of the splenium. No sexual dimorphism could be demonstrated until the beginning of the postnatal period. In the age group between birth (at term) and the 14th month, CCA was, as in the adult, larger in males. Unlike in the adults, the CC was longer in males and the bulbosity index was the same in the two sexes. Axonal elimination may play a role in the perinatal pause in CCA growth and in the concomitant changes in callosal sh

ISSN:0092-7317    

DOI:10.1002/cne.902800205

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe projections of primary afferents from rostral cervical segments to the brainstem and the spinal cord of the rat were investigated by using anterograde and transganglionic transport techniques. Projections from whole spinal ganglia were compared with those from single nerves carrying only exteroceptive or proprioceptive fibers. Injections of horseradish peroxidase (HRP) or wheat germ agglutinin‐horseradish peroxidase conjugate (WGA‐HRP) were performed into dorsal root ganglia C2, C3, and C4. Free HRP was applied to the cut dorsal rami C2 and C3, greater occipital nerve, sternomastoid nerve, and to the C1/2 anastomosis, which contains afferents from suboccipital muscles and the atlanto‐occipital joint. WGA‐HRP injections into ganglia C7 and L5 were performed for comparative purposes.Injections of WGA‐HRP or free HRP into rostral cervical dorsal root ganglia and HRP application to C2 and C3 dorsal rami produced labeling in dorsal and ventral horns at the level of entrance, the central cervical nucleus, and in external and main cuneate nuclei. From axons ascending to pontine and descending to upper thoracic spinal levels, medial collaterals were distributed to medial and descending vestibular, perihypoglossal and solitary nuclei, and the intermediate zone and Clarke's nucleus dorsalis in the spinal cord. Lateral collaterals projected mainly to the trigeminal subnucleus interpolaris and to lateral spinal laminae IV and V.Results from HRP application to single peripheral nerves indicated that medial collaterals were almost exclusively proprioceptive, whereas lateral collaterals were largely exteroceptive with a contribution from suboccipital proprioceptive fibers. WGA‐HRP injections into dorsal root ganglia C7 and L5 failed to produce significant labeling within vestibular and periphypoglossal nuclei, although they demonstrated classical projection sites within the brainstem and spinal cord.The consistent collateralisation pattern of rostral cervical afferents along their whole rostrocaudal course enables them to contact a variety of precerebellar, vestibulospinal, and preoculomotor neurons. These connections reflect the well‐known significance of proprioceptice neck afferents for the control of posture, head position, and

ISSN:0092-7317    

DOI:10.1002/cne.902800206

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractSpecific antibodies against gamma aminobutyric acid (GABA) and glutamic acid decarboxylase (GAD) were used to study the organization of the GABAergic system in the rat hippocampal formation. Both the number of GABA‐like‐immunoreactive (Li) somata and neuropil density were assessed in semithin sections. Cell counts revealed that approximately 11% of the hippocampal neuronal population showed GABA‐Li within the various planes of section.Each layer in the hippocampal formation had a characteristic organization of GABA‐Li elements. In Ammon's horn, 80–95% of the neuronal somata within the apical and basal dendritic regions were GABA‐Li positive. Within the pyramidal cell layer 5–8% of the cells were GABA‐Li in the CA1 to CA3 subfields of Ammon's horn and only 3% were GABA‐Li within that portion of the pyramidal cell layer that inserts into the hilus. Only slight differences in the density of the GABA‐Li neuropil were observed within the CA1‐CA3 dendritic regions. Restricted to the stratum lucidum was a dense band of GABA‐Li label. Counts of immunoreactive grains localized on the perimeter of pyramidal (CA1‐CA3) and granule somata revealed more terminal boutons on the CA3 cells than on CA1 and granule neuronal somata.A topographical distribution of GABA‐Li somata and neuropil was found in the fascia dentata: There the label particularly concerned its suprapyramidal and rostrolateral portions. Approximately 40% of neurons in the molecular layer, 60% in the polymorph layer, and 18% within the hilar region were GABA‐Li. Within the granule cell layer only 2% of the neurons were GABA‐Li positive. Distinct differences in the density of the GABA‐Li neuropil were present in the molecular, pericellular granular, and hilar regions of the fascia dentata.While the morphology of GABA‐Li neuronal somata varied according to their hippocampal layer, the most heterogeneous cell types were found in the regio inferior of the hippocampus. There we have identified neurons that are reminiscent of the inferior region interneuron described in Golgi material by Amaral and Woodward (Brain Res.124:225–236, '77). Moreover, particularly in the sagittal plane, we have identified oval, triangular, and round cells and that have processes oriented in a parallel arrangement, appearing to be aligne

ISSN:0092-7317    

DOI:10.1002/cne.902800207

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe basal forebrain magnocellular complex of primates is defined by the presence of large, hyperchromic, usually cholinergic neurons in the nucleus basalis of Meynert and nucleus of the diagonal band of Broca. Because there is growing evidence for noncholinergic neuronal elements in the basal forebrain complex, five neuropeptides and the enzyme choline acetyltransferase were studied immunocytochemically in this region of rhesus monkeys. Galaninlike immunoreactivity coexists with choline‐acetyl‐transferase‐like immunoreactivity in most large neurons and in some smaller neurons of the primate nucleus basalis and nucleus of the diagnonal band. Four other peptides show immunoreactivity in more limited regions of the basal forebrain complex, usually in separate smaller, noncholinergic neurons. Numerous small, somatostatinlike‐immunoreactive neurons occupy primarily anterior and intermediate segments of the nucleus basalis, especially laterally and ventrally. Somewhat fewer, small neuropeptide Y‐like‐immunoreactive somata are found in the same regions. Neurons that show neurotensinlike immunoreactivity are slightly larger than cells that contain immunoreactivity for somatostatin or neuropeptide Y, but these neurons also occur mainly in anterior and intermediate parts of the nucleus basalis. Overall, the usually small, leucine‐enkephalin‐like‐immunoreactive neurons are infrequent in the basal forebrain complex and are most abundant in the rostral intermediate nucleus basalis. Thus, neurons that appear to contain somatostatin, neuropeptide Y, neurotensin, or enkephalin mingle with cholinergic/galaninergic neurons only in some subdivisions of the nucleus basalis/nucleus of the diagonal band, and their distributions suggest that some of these small neurons could be associated with structures that overlap with cholinergic neurons of the labyrinthine basal forebrain magnocellular complex. We also have found light microscopic evidence for innervation of basal forebrain cholinergic neurons by boutons that contain galanin‐, somatostatin‐, neuropeptide Y‐, neurotensin‐, or enkephalinlike immunoreactivity. The origins and functions of these putative synapse

ISSN:0092-7317    

DOI:10.1002/cne.902800208

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractUsing a monoclonal antibody to choline acetyltransferase (ChAT), we have identified immunoreactive synaptic terminals in the neuropil regions of the cephalic ganglion ofDrosophila melanogaster. This study demonstrates the distribution of antibody‐labeled structures within the optic lobe, and then investigates the immunoreactivity altered by mutation in two temperature‐sensitive ChAT alleles,chats−1andchats−2.The general structure of the optic lobe was first observed by means of the silver impregnation technique. Then the presence of ChAT immunoreactivity was determined by the application of antibody [1G4] conjugated with HRP to frozen sections, followed by the 3,3′‐diamino‐benzidine tetratinct layers, which correspond to the three synaptic layers of the laminarneurons, in the medulla. Also, staining appeared in four distinct layers in the lobula. In addition, weaker staining was observed in the lamina, which corresponds to the retinula cell terminals. Somal layers were not stained.In Canton‐S (wild‐type), the three medullar layers stain distinctly at both 19°C and 30°C. Inchats−1at 19°C, the stain appeared in the same layers as that of Canton‐S, but with somewhat lower density. Inchats−2at 19°C, the density of the stain was even lower. The densities of the stain in these mutants were further decreased after exposing the flies to 30°C. The decreases were dependent on the length of exposure to the higher temperature. The decrease in stain of the specimens obtained after 24 hours exposure to 30°C was clearly recognizable in bothchats−1andchats−2. The stain was visually unrecognizable after 120 hrs incubation at 30°C inchats−1, and after 80 hrs inchats−2. The stained structures in the medulla are apparently terminals of the laminar neurons. α‐Bungarotoxin (α‐BTX) conjugated with HRP and visualized by the DAB‐H2O2reaction was also used to stain frozen sections of wild‐type and mutantDrosophila.The three layers of α‐BTX‐HRP stained structures in the medulla overlapped with the layers revealed by 1G4. Exposure to high temperature (30°C) for up to 120 hours did not show any effect on the stain obtained by α‐BTX‐HRP in either allele.These results show that 1G4, a monoclonal antibody specific forDrosophilaChAT, can be used to identify ChAT‐containing neurons. In the temperature‐ sensitive ChAT mutant,chats, the reduced immunoreactivity paralleled the reduc

ISSN:0092-7317    

DOI:10.1002/cne.902800209

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe distribution of calcitonin‐gene‐related peptide (CGRP) immunoreactivity (IR) was studied in peripheral tissues of rats. The ganglionic origin, somatosensory nature, and anatomic relations of this thin‐axon population were evaluated with particular emphasis on possible nociceptive roles. In animals untreated with colchicine, CGRP‐IR is found in a vast proportion of small‐ and medium‐diameter sensory ganglion cells that give rise to numerous thinly myelinated and unmyelinated axons that display CGRP‐IR throughout the body.The integumentary innervation consists, in part, of an extensive subpapillary network largely traced to dermal blood vessels, sweat glands, and “free” nerve endings, some of which are found within regions containing only mast cells, fibroblasts, and collagen. Dermal papillae contain CGRP‐IR axons surrounding each vascular loop; other papillary axons end freely or occasionally surround Meissner corpuscles. Intraepithelial axons enter glabrous epidermal pegs, branching and exhibiting terminals throughout the stratum spinosum. A similar pattern is found in hairy skin with additional innervation entering the base and surrounding the lower third of each hair follicle, but apparently not supplying sebaceous glands and arrector pili muscle. Axons innervating nonkeratinized oral epithelium are similar or greater in number and distribution compared to epidermis, often with more extensive branching. The high density of intraepithelial CGRP‐IR innervation does not appear to correlate with the sensitive mechanoreceptor‐based increase in spatial sensory discriminative capacities in the distal portions of the limb.In deep somatic tissues, CGRP‐IR is principally related to vasculature and motor end plates of striated muscle, but there is an extensive network of thin axons within bone, principally in the periosteum, and focally in joint capsules, but not in relation to muscle spindles or tendon organs.These findings, together with the distribution in cranial tissues described in an accompanying paper (Silverman and Kruger:J. Comp. Neurol. 280:303–330, '89), are considered in the context of a “noceffector” concept incorporating theefferentrole of these sensory axons in various tissues. It is suggested that involvement in tissue maintenance and renewal during normal function, as well as following injury, may predominate over the relatively infrequent nociceptive role of

ISSN:0092-7317    

DOI:10.1002/cne.902800210

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe distribution of calcitonin‐gene‐related peptide‐like immunoreactivity (CGRP‐IR) was studied in sections of decalcified rat head and selected whole‐mount preparations in order to address the complex peptidergic innervation patterns in peripheral cephalic specialized zones and to examine neuronal ganglia in situ.Labeled neuron somata in trigeminal, glossopharyngeal, and vagal ganglia comprised a large proportion of small to medium size type B ganglion cells. Parasympathetic ganglia (ciliary, otic, sphenopalatine, submandibular) revealed a small population of labeled somata and numerous perisomatic IR axons, whereas sympathetic ganglion cells (superior cervical) were devoid of label though richly innervated by perisomatic IR axons. The gustatory geniculate ganglion contained only a few labeled neurons and axons.Coarse peripheral CGRP‐IR axons were traced to skeletal muscle motor end plates (e.g., lingual, tensor tympani, etc.), and thin sensory axons most densely innervated the cornea, iris, general integument, all mucosal epithelia lining the tympanic, nasal, sinus and oropharyngeal cavities, and the cerebral meninges. Blood vessels, glands, ducts, and their orifices were often heavily innervated, and specific specializations and exceptions are discussed.Distinctive patterns of IR innervation characterized the various specialized sensory systems, including (1) cochlear and vestibular hair cells; (2) lingual, palatal, oropharyngeal, and laryngoepiglottal taste buds; (3) main olfactory epithelium and axons projecting to glomeruli in specific sectors of main olfactory bulb; (4) septal‐olfactory organ; (5) vomeronasal organ; and (6) the nervus terminalis system. Secretory epithelia (ciliary body, choroid plexus, and stria vascularis) were notably lacking in CGRP‐IR.Despite the multiplicity of functionally distinct CGRP neuronal and axonal populations, certain generalizations merit consideration. The extensive innervation of chemosensory nasal and oral epithelia may contribute to specific chemical sensitivities (e.g., relating to olfactory and gustatory senses) as well as evoking “nociceptive” responses to chemical irritants as part of a “common chemical sense.” Anefferentrole for some of these peptidergic afferent axons may also be inferred from their specific distributions. Sites involved in regulating access to and sensitivity of sense organs to external stimuli (e.g., cochlear and vestibular hair cells, taste bud orifices, and main olfactory epithelium) are heavily innervated. Other IR axons are in position to exert control over airflow through nasal turbinates, glandular secretion, blood circulation, and duct transport systems. The widespread distribution of “free” nerve endings in ocular, nasal, and oral epithelia may serve versatile roles in response to noxious chemical stimuli, permitting “sensory” axon modulation of autonomic neuron activity and triggering of protective reflexes. Direct peptidergic axon effector control of stimulus‐evoked processes including secretion (e.g., salivation), bronchoconstriction, the ocular injury response, and generalized withdrawal from aversive stimuli might also be

ISSN:0092-7317    

DOI:10.1002/cne.902800211

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY