摘要:

AbstractWe have examined the possibility that reinnervation of a new peripheral target by primary afferent neurones can alter the histochemical properties of those afferents in the adult rat. The hindlimb sural and gastrocnemius nerves largely supply skin and muscle, respectively. In adult animals these nerves were cut and rejoined to either their own distal stumps (self‐anastomosis) or that of the other nerve (cross‐anastomosis) and allowed to regenerate for 12‐16 weeks to reinnervate an appropriate or inappropriate target. Fluoride‐resistant acid phosphatase (FRAP) is a chemical marker found in many unmyelinated afferents. We have determined the FRAP expression in normal and regrown nerves and examined its distribution in the dorsal horn of animals with self‐ and cross‐anastomosed nerves.While normal and self‐anastomosed sural nerves stained heavily for FRAP, gastrocnemius nerves showed either no staining or only the occasional fibre. Cross‐anastomosed gastrocnemius nerves, now innervating the skin, showed a significant increase in staining, in some cases approaching the levels normally seen in sural nerves. Conversely, cross‐anastomosed sural nerves (innervating muscle) showed decreased FRAP staining. In the normal dorsal horn the terminals of FRAP containing afferents form a thin band extending throughout the mediolateral extent of lamina II (Devor and Claman:Brain Res. 190:17‐28, '80). One week after axotomy of the sural nerve, FRAP is depleted from its terminals and a gap appears in the normal FRAP staining pattern in the lumbar enlargement of the spinal cord. The new expression of FRAP in cross‐anastomosed nerves was also seen in their terminals in the dorsal horn. This occurred in lamina II of the spinal segments L4‐L6 and was quantified by measuring the size of the gap in FRAP staining produced by sural axotomy. Cross‐anastomosis of the gastrocnemius nerve reduced the size of the gap significantly to 69 ± 7.8% (standard error) of the gap seen contralaterally with self‐anastomosis.The results demonstrate that reinnervation of an inappropriate target can lead to changes in the histochemical properties of afferents in adult animals. It is suggested that tissue‐specific trophic factors produced by the target tissues are sampled by innervating neurones and

ISSN:0092-7317    

DOI:10.1002/cne.902740102

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe ultrastructural localization of sensory nerves in the rat kidney was examined by using the chromaffin reaction to distinguish sympathetic catecholaminergic fibres from sensory fibres. The sensory fibres were further characterized by use of an immunoperoxidase staining method to identify nerves immunoreactive for substance P and for calcitonin‐gene‐related peptide. Sympathetic fibres were observed in the renal cortex, medulla, and pelvis, but sensory fibres were seen only in the renal pelvis. Immunostaining for substance P labelled 40% of the sensory fibres. Following incubation in calcitonin‐gene‐related peptide antiserum, 53% of the sensory nerves were positively stained. Simultaneous immunostaining for substance P and calcitonin‐gene‐related peptide resulted in immunoreactivity in 82% of the sensory fibres, a percentage of axons significantly lower than that expected if the axons containing each peptide had been entirely separate populations. The results indicate that sensory nerves in the rat kidney are located entirely in the renal pelvis. On the basis of their neuropeptide content, there appear to be at least four separate populations of sensory axons present: two large groups containing substance P or calcitonin‐gene‐related peptide alone and two small groups containing both peptides and con

ISSN:0092-7317    

DOI:10.1002/cne.902740103

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractIntracellular electrodes filled with 4% horseradish peroxidase (HRP) were used to impale Purkinje cells in zone x of the cat's cerebellum. Subsequent to recording responses to bilateral stimulation of the ulnar, radial, and sciatic nerves, the cells were injected with HRP. Intracellularly labeled Purkinje cells were located and correlated with the physiological data. Purkinje cells in zone x respond primarily to stimulation of the ipsilateral forelimb. However, they have broad receptive fields in that most also receive inputs from stimulation of the contralateral forelimb or from more than one forelimb nerve; a few respond to activation of the hindlimb.The distribution of the recurrent collaterals of zone x Purkinje cells has several features that are similar to those from zones a, b, and c: (1) they have a similar number of varicosities within the plexus; (2) they distribute primarily in the sagittal as compared to the transverse plane; and (3) most varicosities in the plexus are located within the Purkinje cell layer. However, several characteristics distinguish the collaterals of zone x Purkinje cells. First, they have a greater transverse extent than those derived from Purkinje cells in zones a, b, and c. Second, they have a higher percentage of collaterals that extend to more superficial aspects of the molecular layer as well as to deep levels of the granule cell layer.The rostral extent of zone x has not been clearly defined in previous studies. On the basis of anatomical and physiological data derived from the present study it appears that Purkinje cells located in lobule Va have physiological and morphological properties similar to those observed for Purkinje cells in more caudal folia of lobule V. Thus, on the basis of the organization of local circuits, it appears that zone x extends at least to the most rostral folia of lobule V.In conclusion, these data suggest that Purkinje cells in zone x may not be involved in controlling the movements of specific muscles, as may be the case in other cortical zones. Rather, it could be hypothesized that Purkinje cells in zone x have a more generalized role in coordinating agonist and antagonist muscle groups in one limb or regulating patterns of movement between limbs.

ISSN:0092-7317    

DOI:10.1002/cne.902740104

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe early development of serotonin‐containing neurons was studied in wholemounts of the fetal rat brain (E12–E18). The wholemounts were treated immunocytochemically according to an immunoperoxidase technique to reveal a panorama of developing serotoninergic neurons. Serotoninergic neurons were localized to two discrete groups or clusters within the brainstem. Serotonin‐containing neurons were identified first at E12 forming a rostral cluster of cells just caudal to the mesencephalic flexure. The more caudal cluster of cells first appeared at E14 in the medulla. During the period from E12 to E18, the immunoreactive cells increased in number and acquired a more complex dendritic tree while migrating to their permanent position. At E16, cells of the rostral group exhibited remarkably uniform mediolateral orientation.The rostral group of immunoreactive neurons gave rise to almost all ascending fibers, whereas the caudal group gave rise to the majority of descending fibers. Growing serotoninergic fibers were tipped by prominent growth cones, which were strongly immunoreactive. The fibers demonstrated prominent orientational selectivity with an almost total separation into ascending and descending bundles. Some of the ascending immunoreactive fibers displayed acute changes in their direction of growth, suggesting that the orientation of serotininergic fibers is mediated by directional cues that are specific to particular populations of serotoninergic fibers. Serotoninergic axons within the medial forebrain bundle were demonstrated particularly well and their ascent and rate of growth toward the forebrain could be easily followed. Immunoreactive fibers entered the telencephalon at E17 two portals, one along the lateral border of the hypothalamus and one rostrally, adjacent to the olfactory tubercle. In wholemounts at E18, fibers arising from this latter location could be followed as two distinct bands within the pallium; a basal band located ventrolaterally, adjacent to the lateral olfactory tract, and a dorsal band located at the medial edge of the telencephalon. Both fascicles were directed toward the occipital pole and contained unbranched fibers. At E18, serotoninergic axons arising from these two loosely organized fascicles covered most of the frontal telencephalon.The results of the present study indicate that wholemounts of embryonic brain can provide novel spaciotemporal data on the development of neuro‐transmitter systems and may in the future prove to be useful experimental preparations in developmental neuro

ISSN:0092-7317    

DOI:10.1002/cne.902740105

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe centrifugal projection to the retina in anuran amphibians (Rana catesbeianaandXenopus laevis) has been investigated by immunocytochemistry, HRP transport, and optic nerve lesionings. FMRFamide‐ and N‐terminal substance P–immunoreactive (Fa‐ir and SP(3–7)‐ir) fibers were abundant in the normal retina and optic nerve but almost absent distal to an optic nerve section or crush after 7–14 days survival. Fa‐ir and SP(3–7)‐ir fibers were traced to the optic nerve from the lamina terminalis (or the septopreoptic junctional area), where there are many Fa‐ir and SP(3–7)‐ir perikarya. After application of HRP to the optic nerve and survival for 9–10 days, retrogradely labeled neurons were observed in the lamina terminalis. Conversely, following HRP injection into the septal and preoptic area, labeled fibers were observed in the optic nerve. These results suggest that Fa‐ir and SP(3–7)‐ir efferent fibers project from the lamina terminalis to the retina. But in anurans, unlike teleosts, these fibers are not gonadotropin‐releasing‐hormone (GnRH)‐ir. The morphological relations of this retinopetal pathway with the

ISSN:0092-7317    

DOI:10.1002/cne.902740106

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe distribution of neural inputs to the paraventricular (PVH) and supraoptic (SO) nuclei from the regions of the A1, the A2, and the A6 (locus coeruleus) noradrenergic cell groups was investigated by using a plant lectin,Phaseolus vulgarisleucoagglutinin (PHA‐L), as an anterogradely transported tracer. An immunofluorescence double‐labeling procedure was used to determine the extent to which individual anterogradely labeled fibers and terminals in the PVH and the SO also displayed immunoreactive dopamine‐β‐hydroxylase (DBH), a marker for catecholaminergic neurons. The results may be summarized as follows: (1) Projections from the A1 region were found primarily, and in some experiments almost exclusively, in those parts of the magnocellular division of the PVH and the SO known to contain vasopressinergic neurons. (2) Projections from the A2 region were distributed primarily throughout the parvicellular division of the PVH and were most dense in the dorsal medial part, a region known to contain a prominent population of corticotropin‐releasing factor (CRF)‐immunoreactive neurons. In addition, a less‐dense projection to the magnocellular division of the PVH and to the SO was consistently found. (3) Fibers originating from the locus coeruleus were distributed almost exclusively to the parvicellular division of the PVH, with the most prominent input localized to the periventricular zone, a part of the PVH known to contain dopamine‐, somatostatin‐, and thyrotropin‐releasing‐hormone‐containing neurons. We found no evidence for a projection from A6 to the SO. (4) The majority of fibers originating from the A1, the A2 or the A6 regions contained DBH immunoreactivity, although an appreciable number did not. These results suggest that each of the three brainstem noradrenergic cell groups that contribute to the innervation of the PVH and/or the SO is in a position to modulate the activity of anatomically and chemically distinct groups o

ISSN:0092-7317    

DOI:10.1002/cne.902740107

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractTritiated thymidine autoradiography experiments demonstrated that three cell classes are produced by ventricular cells during the first phase of neurogenesis: retinal ganglion cells, A‐type horizontal cells, and cone photoreceptors. Light microscopy and scanning electron microscopy were used to study the migration and morphological differentiation of these three cell classes.The patterns of postmitotic migration are of interest because these three classes of cells are found in three different layers of the adult retina. Cones retain their position at the outer limiting membrane (OLM) throughout life and do not migrate. Ganglion cells migrate immediately to the proximal (vitread) layer of the retina and begin to differentiate. In contrast, A‐type horizontal cells migrated away from the OLM within 10–14 days after their final mitosis but were morphologically relatively undifferentiated at that time. Subsequent differentiation of the A‐type horizontal cell is also protracted; dendrites are not observed until approximately 3 weeks after the final mitosis.These observations suggest that there are several interacting mechanisms involved in neurogenesis: a sequence that produces a specific cohort of committed cells at a specific time, the subsequent migration of postmitotic neuroblasts to an appropriate position in the retina, and a spatial gradient of differentiation increasing from distal to proximal layers. While this distribution of differentiated cells early in fetal development is striking, the existence of underlying time‐dependent processes that might cause this apparent spatial phenomenon cannot be e

ISSN:0092-7317    

DOI:10.1002/cne.902740108

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractDirect projections to the cingulate gyrus from the thalamic region lying just ventrally to the ventral border of the ventrobasal complex (VB) were found in the cat by two sets of experiments that used WGA‐HRP (wheat germ agglutinin‐horseradish peroxidase conjugate).In the first set of experiments, WGA‐HRP was injected into the thalamic region around the ventral border of the VB. When the site of injection involved the thalamic region lying ventrally to the ventral border of the VB at the levels of the caudal two thirds of the VB. The cerebral cortex in the rostral part of the cingulate gyrus ipsilateral to the WGA‐HRP injection contained fine HRP‐positive granules, which indicated anterograde labeling of axon terminals. These labeled presumed axon terminals were mainly distributed to the superficial part of layer I, deep part of layer II, layer IV, and the most superficial part of layer V in the cingulate cortex.In the second set of experiments, WGA‐HRP was injected into the cerebral cortex of the rostral part of the cingulate gyrus. When the site of injection involved the region of the cingulate gyrus, where presumed axon terminals had been labeled in the first set of experiments, the thalamic region just ventral to the ventral margin of the caudal two‐thirds of the VB ipsilateral to the WGA‐HRP injection contained neuronal cell bodies labeled retrogradely.The results indicate that some neurons that are located in the thalamic region just ventral to the ventral border of the caudal two‐thirds of the VB send their axons to the cerebral cortex in the rostral part of the cingulate gyrus.The possible significance of the thalamocingulate projection found in the present study is discussed with relation to nociceptive beha

ISSN:0092-7317    

DOI:10.1002/cne.902740109

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractRetrograde tracing techniques were employed to determine whether transection of the infraorbital (IO) nerve in either newborn or adult rats resulted in peripheral sprouting by undamaged trigeminal (V) axons. The IO nerve was sectioned just behind the vibrissa pad, either on the day of birth or when animals reached at least 60 days of age. After an additional 60 days, the same nerve was retransected in the orbit; horseradish peroxidase (HRP) or diamidino yellow (DY) was injected into the central portion of the vibrissa pad; and animals were killed 2–3 days later. In the neonatally nerve‐damaged rats, this procedure invariably labelled primary afferent neurons in both the ipsilateral and contralateral V ganglia. On the ipsilateral side, these cells were located in the caudal portion of the ophthalmicmaxillary region and, less often, in the mandibular division. Their average diameter was 22.6 μm (s.d.=5.6). On the contralateral side, most labelled ganglion cells were visible in the anteromedial part of the ophthalmicmaxillary region but a few could also be seen in the mandibular division. Their average diameter was 21.1 μm (s.d.=5.5). No labelled ganglion cells were observed in adult rats subjected to the same series of manipulations.In a separate series of neonatally nerve‐damaged animals, the above‐described procedures were combined with neonatal injection of capsaicin in an effort to determine whether the observed sprouting was dependent upon the presence of large numbers of unmyelinated axons. The addition of this treatment reduced the number of labelled cells in both the ipsilateral and contralateral ganglia, but it did not alter either their distribution or average soma diameter.In a final experiment, sequential double‐labelling techniques were used to determine whether the V axons that projected to the vibrissa pad via non‐IO nerve branches were the result of sprouting by undamaged ganglion cells or arose from neurons that had originally projected into the IO nerve, were axotomized by our lesions, and regenerated to the vibrissa pad via another V branch. Here, the long‐lived retrograde tracer true blue (TB) was injected into the vibrissa pad 6–8 hours before the neonatal nerve cut and DY was deposited into the pad after transection of the regenerate IO nerve in adulthood. Double‐labelled cells in this experiment would have projected to the vibrissa pad via the IO nerve at birth and regenerated to it via another V branch in adulthood. Nearly 55% of the DY‐labelled cells in this experiment also contained TB. This result indicated that about one‐half of the innervation of the vibrissa pad by non‐IO V branches was the result of axonal sprouting by

ISSN:0092-7317    

DOI:10.1002/cne.902740110

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractCorticothalamic and corticotectal projections from the anterior ectosylvian sulcus (AES) in neonatal cats were studied with anterograde and retrograde neuroanatomical techniques. When the injection site was relatively restricted to the sulcal walls and fundus of the rostral AES (i.e., the SIV cortex), heavy ipsilateral thalamic label was observed in the medial subdivision of the posterior group, in the suprageniculate nucleus, and in the external medullary lamina. No terminal label was seen in the contralateral thalamus although the contralateral homotopic cortex was heavily labeled. Within the ventrobasal complex (VB), dense axonal label was observed in fascicles that traversed VB, but only light terminal label was observed within VB itself. However, in cases where the tracer spread into adjacent SII, terminal label in VB was pronounced. Similarly, when the injection site extended into auditory cortex, terminal label was observed in the lateral and intermediate subdivisions of the posterior group.Rostral AES injections produced distinct, predominantly ipsilateral, terminal label in the superior colliculus that was distributed in two tiers: a discontinuous band in the stratum griseum intermedium and a more diffuse band in stratum griseum profundum. Caudally, dense terminal label was seen in the intercollicular zone and dorsolateral periaqueductal gray. When the injection site did not include rostral AES, no label was observed in the superior colliculus. Horseradish peroxidase injections into the superior colliculus of neonates produced retrogradely labeled neurons throughout the AES, but none was found on the crown of the gyrus where SII is located. Thus, the neonatal corticotectal somatosensory projection arises exclusively from AES and parallels that found in adults.These data indicate that the elaboration of a major descending somatosensory pathway from AES to the thalamus and midbrain is largely a prenatal event. The in utero anatomical maturation of the corticofugal projections from SIV cortex to the superior colliculus contrasts with the protracted postnatal development of the corticotrigeminal projections from SI cortex but is consistent with the mature anatomical state of ascending trigeminotectal projections.

ISSN:0092-7317    

DOI:10.1002/cne.902740111

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY