摘要:

AbstractThe position of ganglion cells contributing to the early imprecision in retinotopic order in the developing retinocollicular projection in the wallaby (Macropus eugenii) has been determined.Deposits of horseradish peroxidase conjugated to wheat germ agglutinin (WGA‐HRP) were made in the caudal pole of the superior colliculus (SC) at ages ranging from 22 days after birth, when sparse retinal axons have only just reached the caudal pole of the SC and are yet to cover its surface completely, to 96 days when the retinotopy of ganglion cell terminals in the SC is precise (Marotte, '90). From 30 days onwards, the deposit of WGA‐HRP resulted in a dense patch of retrogradely labelled retinal ganglion cells that could be seen to be appropriately positioned in nasal retina. However, at all ages prior to 92 days, there were inappropriately positioned labelled cells between the densely labelled patch and the central retina and both dorsal and ventral to the patch. They were not found in far distant regions of retina and composed a relatively small proportion of labelled cells. They reached a peak at 45 days, had decreased to low levels by 63 days, were rare by 81 days, and by 92 days were absent. This latter age fits with the time when retinotopy was judged to be precise in a previous study (Marotte, '90).Inappropriately projecting cells never originate from the entire retina but only from regions adjacent to the appropriate region. Thus, during development there are no gross projection errors. Initially, ganglion cell axons are distributed on the colliculus in a coarse retinotopy. Refinement of the projection then follows, revealed by this technique as a loss of inappropriately projecting ganglion cells. This is complete by 92 days well before eye opening at around 140 days. © 1993 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903310102

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe calcium‐binding protein parvalbumin was immunohistochemically localized in the monkey amygdaloid complex. Parvalbumin‐immunoreactive neuronal cell bodies, fibers, and terminals were observed in several amygdaloid nuclei and cortical areas. Three types of aspiny neurons, ranging from small spherical cells (Type 1) to large multipolar cells (Type 2) and fusiform cells (Type 3) were observed in most amygdaloid regions, though the proportions of the cell types were different in each region. The density of parvalbumin‐immunoreactive fibers and terminals tended to parallel the density of labeled cell bodies. The highest densities of parvalbumin profiles were observed in the nucleus of the lateral olfactory tract, the periamygdaloid cortex (PAC2), the magnocellular division of the basal nucleus, the ventrolateral portion of the lateral nucleus, and the accessory basal nucleus. The regions containing the lowest densities of parvalbumin‐positive profiles were the medial nucleus, anterior cortical nucleus, central nucleus, and the paralaminar nucleus. In regions with fiber and terminal labeling, pericellular networks of fibers, reminiscent of basket cell terminations, were commonly observed to surround unstained neuronal cell bodies and proximal dendrites. In the magnocellular division of the basal nucleus, and to a lesser extent in the lateral nucleus, parvalbuminlabeled “cartridges” of axo‐axonic terminals were observed on the initial segments of unlabeled cells. Parvalbumin‐positive varicosities were also commonly observed in close apposition to the soma and dendrites of parvalbumin‐immunoreactive cells. Given the close correspondence between the distribution of parvalbumin‐positive neurons and a subset of GABAergic neurons in many brain regions, these data provide a first indication of the organization of the inhibitory circuitry of the primate amygdaloid complex. ©

ISSN:0092-7317    

DOI:10.1002/cne.903310103

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe distribution of parvalbumin‐immunoreactive cells and fibers in the various fields of the hippocampal formation was studied in the macaque monkey. Parvalbumin‐immunoreactive neurons had aspiny or sparsely spiny dendrites that often had a beaded appearance; most resembled classically identified interneurons. Parvalbumin‐immunoreactive fibers and terminals were confined to certain laminae in each field and generally had a pericellular distribution. In the dentate gyrus, there was a dense pericellular plexus of immunoreactive terminals in the granule cell layer. Except for a narrow supragranular zone, there was a marked paucity of terminals in the molecular and polymorphic cell layers. Immunoreactive neurons were mainly located immediately subjacent to the granule cell layer and comprised a variety of morphological cell types. The three fields of the hippocampus proper (CA3, CA2, and CA1) demonstrated differences in their parvalbumin staining characteristics. In CA3, there was a prominent pericellular terminal plexus in the pyramidal cell layer that was densest distally (closer to CA2). Immunoreactive cells were located either in the pyramidal cell layer, where many had a pyramidal shape and prominent apical and basal dendrites, or in stratum oriens. CA2 had a staining pattern similar to that in CA3, though both the number of labeled cells and the density of the pericellular terminal plexus were greater in CA2. In CA1, there was a markedly lower number of parvalbumin‐labeled cells than in CA3 and CA2 and the cells tended to be located in the deep part of the pyramidal cell layer or in stratum oriens. The pyramidal cell layer of CA1 contained a pericellular terminal plexus that was substantially less dense than in CA3 and CA2. At the border between CA1 and the subiculum there was a marked in the number of parvalbumin‐immunoreactive neurons. The positive cells were scattered throughout the pyramidal cell layer of the subiculum and comprised a variety of sizes and shapes. Terminal labeling was higher in the pyramidal cell layer of the subiculum than in CA1. Layer II of the presubiculum had one of the highest densities of fiber and terminal labeling in the hippocampal formation. The density of staining was lower in the superficial portion of the layer where linear cartridges of presumed axo‐axonic synapses were common. A large number of parvalbuminimmunoreactive cells were scattered throughout layer II of the presubiculum; small, spherical, multipolar cells were commonly observed in layer I. The parasubiculum had a somewhat lower density of positive cells and fibers than the presubiculum. The entorhinal cortex demonstrated a rostrocaudal and mediolateral gradient to its distribution of parvalbumin‐immunoreactive cells, fibers, and terminals. The density of positive structures became increasingly greater along a rostrocaudal gradient and, at all levels, staining was denser in the lateral portion of the entorhinal cortex. This study provides a comprehensive analysis of the distribution of parvalbumin‐immunoreactive profiles in the nonhuman primate hippocampal formation. Since parvalbumin has been found to colocalize with certain classes of GABAergic neurons, this study also provides information on the organization of one component of the inhibitory circuitry of the monkey hippocampal formation. © 1993

ISSN:0092-7317    

DOI:10.1002/cne.903310104

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

年代:1993

数据来源: WILEY

摘要:

AbstractNewly hatched chickens were allowed to survive 6, 10, 15, and 20 weeks after 10 days of gentamycin sulfate treatment. Ultrastructural studies of hair cells and nerve terminals in the auditory receptor organ, the basilar papilla, were carried out with transmission and scanning electron microscopes. Attention was paid to absolute sensory cell (hair cell) numbers, stereocilia maturity and orientation, and reinnervation within a band 100 μm wide centered 1,100 μm from the basal end of the avian cochlea.Sensory cell numbers were equivalent to those of untreated control animals within the study area in the earliest survival group. Both immature and mature appearing hair cells were identified throughout the recovery period. However, the ratio of mature to immature hair cells gradually increased to exceed 95% at 20 weeks. Stereocilia bundle reorientation also occurred throughout the study period. Orientation was often abnormal at 6 weeks, but by 20 weeks more than 95% of the regenerated hair cells were aligned within normal limits established in the control ears. Hair cell differentiation occurring at 10–15 weeks was associated with degeneration of the afferent nerve receptor complexes commonly observed in 6 week survivors. These complexes were replaced by one or two small bouton shaped efferent terminals per cell. At 20 weeks, two or three chalice shaped vesiculated terminals were observed per cell in both the gentamycin treated and control ears.On the basis of these observations normal physiological activity would be predicted at 20 weeks following gentamycin treatment, at which time sensory cell repopulation, maturation, reorientation, and innervation approximates the normal anatomical condition. © 1993 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903310105

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

年代:1993

数据来源: WILEY

摘要:

AbstractRecent reports documented the ability of the posthatch avian vestibular epithelia to produce hair cells continually at a low rate. This project was designed to investigate whether, in addition, the chicken vestibular system is capable of regenerating its sensory epithelium in response to a lesion. Aminoglycoside injections were given to young birds in order to damage the vestibular epithelium. Tritiated thymidine injections were used to label cells produced in response to the lesion. Treatment and age‐matched control animals were killed at 1 day, 20 days, or 60 days after aminoglycoside injections, and vestibular organs were processed for autoradiography. Our results show that the chicken vestibular sensory epithelium is capable of regenerating hair cells after severe damage. Moreover, the epithelium is capable of complete anatomical recovery. Finally, drug damage increases the pace at which hair cells are replaced, compared to the rate of hair cell turnover in untreated tissue. © 1993 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903310106

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe studied the distribution and light‐ and electron‐microscopic morphology of neurons in the hippocampal formation containing nitric oxide synthase (NOS), and thus likely to release nitric oxide, a freely diffusible neuromediator implicated in long‐term potentiation. Only a small fraction of hippocampal neurons contained NOS or its marker, NADPH diaphorase. Most of the positive neurons were in the pyramidal layer of the subiculum, stratum radiatum of Ammon's horn, and subgranular zone of the dentate gyrus. Positive neurons were also conspicuous in the molecular layer of the dentate gyrus and in the pyramidal layer of CA3, sparse in the pyramidal layer of CA2 and CA1, and almost absent from presubiculum and parasubiculum. Numerous positive fibers were seen, especially in stratum radiatum and stratum lacunosum‐moleculare of Ammon's horn. Double staining experiments demonstrated that nearly all NADPH diaphorase‐positive neurons in the hippocampus also contained γ‐aminobutyric acid.On the basis of their morphology, distribution, and inhibitory neurotransmitter content, most NOS‐positive cells in the hippocampus are probably local circuit neurons. These data suggest that nitric oxide in CA1 may function as a paracrine agent, rather than a spatially precise messenger, in long‐term potentiation. © 199

ISSN:0092-7317    

DOI:10.1002/cne.903310107

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

年代:1993

数据来源: WILEY

摘要:

AbstractInnervation of the axolotl lingual epithelium by the glossopharyngeal nerve was examined to reveal its sensory target cells. The carbocyanine dye diI was applied to the nerve stump in the tongue fixed with paraformaldehyde. After a diffusion period of several months, the tongues were examined with a conventional epifluorescence microscope and a confocal laser scanning microscope (LSM) in wholemounts or preparations sectioned with a vibratome. Beneath the epithelium the labeled nerve fibers spread horizontally to form a meshwork of fibers, from which fascicles of fibers extended upward perpendicularly to the epithelium to innervate taste buds. Numerous taste buds were labeled by possible transcellular diffusion of diI. At the base of the taste bud, the nerve fibers branched and formed a basal plexus of fine fibers, on which numerous varicosities were seen. One or at most several taste cells were labeled in a taste bud. In the basal part of taste buds, the cell without an apical process, the basal cell, was also labeled. In the epithelium, between the taste buds, a few solitary cells were labeled. In some cases, a single fascicle of fibers innervating these cells was clearly shown by the LSM. In addition, fine fibers apparently formed free nerve endings in the epithelial cell layer. The results showed that the IX nerve innervated not only taste cells, but also presumed mechanosensory basal cells in the taste bud and the solitary cells of unknown function in the non‐taste lingual epithelium. Afferent nerve responses to mechanical stimulation of the tongue may be explained by these non‐taste cellular elements in the epithelium. © 1993 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903310108

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

年代:1993

数据来源: WILEY

摘要:

AbstractDonor Schwann cells, perineurial cells, and vasculature are known to survive in grafts of peripheral nerve. In the present study, we attempted to cryopreserve nerve to determine whether these cellular components of nerve would survive after transplantation and support host axonal regeneration through the graft. Four‐centimeter lengths of peroneal nerves were removed from inbred adult American Cancer Institute (ACI) rats and placed into vials that contained a cryoprotective mixture of dimethyl sulfoxide and formamide (DF) at room temperature. Each vial with nerves in DF was cooled at a rate of 1–1.5°C/minute down to –40°C at which point the vials were plunged into liquid nitrogen at –196°C. After 5 weeks of storage, the nerves were thawed and DF removed. Some of the cryopreserved‐thawed ACI nerves were transplanted as isografts into the legs of ACI rats. Other ACI nerves were used as allografts and inserted into immunologically normal Fischer (FR) rats that were untreated or were immunosuppressed with the drug Cyclosporin A (Cy‐A). At surgery, only one end of the nerve graft was joined to the cut proximal end of the peroneal nerve of the host. The cellular elements of ACI grafts were present at 5 weeks in grafts removed from ACI rats and FR rats treated with Cy‐A. Non‐immunosuppressed FR rats rejected ACI nerves as did FR rats in whom Cy‐A was stopped after 5 weeks of treatment. All surviving ACI grafts underwent Wallerian degeneration and consisted of columns of Schwann cells, which in their proximal portion were associated with regenerating host axons. The donor perineurial sheath and vasculature were also present in surviving grafts. ACI isografts only were examined 20 weeks postoperatively. All normal tissue components survived in these older grafts and contained regenerated and myelinated host axons throughout their 4 cm lengths. These results demonstrated that the cellular elements of nerve can be cryopreserved, and after transplantation, survive and function. Because nerves survived after prolonged cryopreservation, it seems feasible to establish a nerve bank from which grafts can be withdrawn to repair gaps in injured nerves. However, cryopreserved nerves used as allografts remain immunogenic and require immunosuppression for their survival. Published in 199

ISSN:0092-7317    

DOI:10.1002/cne.903310109

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

年代:1993

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903310101

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

年代:1993

数据来源: WILEY