摘要:

AbstractSpectral sensitivities of photoreceptors in the turtle (Geoclemys) retina were studied by intracellular recording, and each cell was filled with Lucifer yellow (LY). Photoreceptors were classified into seven morphological types: rod, four types of single cones, and two members of a double cone. Single cones contained one of four different oil droplets: red, pale‐green, orange, and clear. Double cones consisted of two apposed cones; principal members contained yellow oil droplets, while accessory members contained no oil droplet. Spectral sensitivities recorded from these seven types of photoreceptors were classified into one type of rod and three chromatic types of cones. Rods (n = 19) showed peak sensitivity at 520 nm. Single cones containing either a red (n = 51) or a pale‐green (n = 9) oil droplet were red‐sensitive (λmax at 620 nm). Single cones containing an orange oil droplet (n = 14) were green‐sensitive (λmax at 540 nm). Single cones containing a clear oil droplet (n = 3) were blue‐sensitive (λmax at 460 nm). Both members of the double cone, principal (n = 22) and accessory (n = 15), were red‐sensitive (λmax at 620 nm) No diffusion of LY was detected between the apposed members of double cones. Red‐sensitive cones, therefore, consisted of four different morphological types of cones, and they occupy about 70% of the photoreceptor mosaic in

ISSN:0092-7317    

DOI:10.1002/cne.902370202

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractDouble retrograde axonal tracing experiments were carried out in order to reveal potential patterns of divergence in axonal projections from the two major sensory nuclei of the mouse brainstem trigeminal complex: the principal sensory and spinal trigeminal nuclei (oralis, interpolaris, and caudalis divisions). The tracers wheat germ agglutinin, N‐[acetyl‐3H] and horseradish peroxidase were used in paired injection strategies within portions of the cerebellum, superior colliculus, and thalamic ventrobasal complex and/or posterior group of adult ICR white mice.Trigeminal neurons with projections to tactile areas of the cerebellar cortex or underlying deep cerebellar nuclei were found scattered throughout the principal sensory nucleus and interpolaris division, and mainly in dorsal regions of the oralis division of the spinal trigeminal nucleus. Injections of either tracer which involved lateral portions of the rostral half of the superior colliculus labeled trigeminotectal neurons mainly in the contralateral interpolaris division, ventral half of the oralis division, and a ventral region of the principal sensory nucleus near the oralis border. Fewer trigeminotectal neurons were found scattered throughout the principal sensory nucleus and the magnocellular layer of the caudalis divisions, although an occasional labeled neuron was also found in the marginal layer. Contralaterally projecting trigeminothalamic neurons were observed throughout the principal sensory nucleus, interpolaris division, and within the marginal and magnocellular layers of caudalis.Double‐labeled neurons were observed only after paired injections of the tracers in the thalamus and ipsilateral superior colliculus, and they were found within the caudoventral portion of the principal sensory nucleus near the oralis border, throughout the interpolaris division, within the magnocellular layer of caudalis, and only a few double‐labeled neurons were also found within the marginal layer. After such injections. 50% of the labeled tectum‐projecting neurons in the principal sensory nucleus, 64% in the interpolaris division, and 57% in the caudalis division are branched neurons which have collateralized projections to both the superior colliculus and thalamus. These projections, which have not been described before, appear to arise from more than one class of projection neuron which is differentially distributed within different regions of the t

ISSN:0092-7317    

DOI:10.1002/cne.902370203

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe distribution of muscarinic cholinergic binding sites in the striatum was studied in relation to the locations of other neurochemical markers in the developing rat, cat, ferret, and human. In addition, patterns of striatal muscarinic binding were studied in the adult cat. Receptor binding autoradiography was carried out with tritiated propylbenzilylcholine mustard ([3H]‐PrBCM), an irreversible muscarinic antagonist, and subsequent serial section analyses involved comparisons among patterns of muscarinic binding, catecholamine histofluorescence, acetylcholinesterase (AChE) staining, Nissl staining, and cell labeling with [3H]‐thymidine.Muscarinic binding in the immature striatum was characterized by local patchiness as well as regional density gradients in all species, with the most complex patterns appearing in the human. Patches of dense muscarinic binding were shown to lie in register with fluorescent dopamine islands (rat, cat, ferret), with AChE‐positive patches (all species), and with clusters of neurons pulse‐labeled by exposure to [3H]‐thymidine on embryonic day 27 (ferret). At the developmental stages examined, the [3H]‐PrBCM‐positive patches were roughly aligned with regions of weak Nissl staining (cat, human).Striatal [3H]‐PrBCM binding in the adult cat was dense, and though it usually appeared nearly homogeneous, in some sections patches of elevated binding were present. These had as counterparts, in neighboring sections, AChE‐poor striosomes. We conclude that during development muscarinic cholinergic function is compartmentalized in the striatum in association with dopamine‐containing afferents, and that this compartmentalization may persist to some

ISSN:0092-7317    

DOI:10.1002/cne.902370204

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractHorseradish peroxidase was intra‐axonally injected into functionally identified primary afferent fibers within the rat spinal trigeminal tract in order to study the morphology of their central terminations. They were physiologically determined to be large, myelinated, cutaneous primary afferents by means of electrical and mechanical stimulation of their receptive fields. Ninety‐three axons that innervated vibrissa follicles, guard hair follicles, and slowly adapting receptors were stained for distances of 4–12 mm at the levels of the main sensory nucleus, spinal trigeminal nucleus, and rostral cervical spinal cord. The collaterals of single axons from these receptors formed terminal arbors in the outer part of the spinal trigeminal nucleus rostral to and near the level of the obex (rostral type collaterals). In the rostral part of the subnucleus caudalis (Vc) they were confined to lamina V (caudalis type collaterals) and in the caudal part of Vc and in cervical segments they were confined to lamina III/IV (spinal‐dorsal‐horn‐type collaterals). There were no transitional forms between the rostral and caudalis types, but there was a transitional form between the caudalis and spinal dorsal horn types. This transitional form was distributed in laminae III/IV and V. The terminal arbors of the rostral type of collaterals formed an interrupted, rostrocaudally oriented column like those seen in the lumbar dorsal horn, but the column shifted down to lamina V near the obex, and more caudally, gradually shifted upward to lamina III. Major morphological differences were not observed among the three different functional types of collaterals with respect to the rostrocaudal distribution of collaterals, and the shape and location of collaterals. The differential laminar distribution of collateral arbors of single axons along the rostrocaudal axis distinguishes the spinal trigeminal nucleus from the spinal dorsal horn where functional types of mechanoreceptive afferents form continuous or interrupted sagittal columns of terminal arbors that do not shift dorsoventrally with

ISSN:0092-7317    

DOI:10.1002/cne.902370205

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe central projections of different groups of cat retinal ganglion cells were studied following small iontophoretic injections of horseradish peroxidase (HRP) into physiologically characterized sites. Analysis was restricted to labeled cells in the upper periphery of the nasal retina, contralateral to the injection site. Injections were made to the A lamina and C lamina of the dorsal lateral geniculate nucleus (LGNd‐A,C), the geniculate wing (LGNd‐W), the ventral lateral geniculate nucleus (LGNv), the pretectum (PT), and the superior colliculus (SC).The dendritic fields of alpha, beta, and epsilon cells were well labeled by the procedures we employed. A group, termed “g1,” had somal sizes within the range of the smaller beta and epsilon cells, but dendritic morphologies distinct from either class. The g1group may consist of a number of types, but our material provided no basis for further distinguishing them. Many cells were observed that had smaller somas; all had thin axons, and few had dendritic fields that labeled to any significant extent. We were not able to further distinguish these cells, and refer to this group, which may include a number of types, as “g2” cells.From the peripheral nasal retina, alpha cells project to LGNd‐A, LGNd‐C, PT, and SC. Beta cells project to LGNd‐A, LGNd‐C, and PT. Epsilon and g1cells project to the LGNd‐C, LGNd‐W, LGNv, PT, and SC.We determined the total spatial density of cells in the region of the retina analyzed, using a Nissl‐stained preparation. We then estimated the relative fraction of cells in each of the above groupings by injecting HRP throughout a cross section of the optic tract. Multiplying this relative fraction by the total spatial density gave an estimate of the spatial density of each of these groupings. From the spatial density of cells labeled from the injection site; we were able to estimate the fraction of cells of each retinal grouping that project to each of the zones investigated.By these calculations, almost all alpha cells from the upper nasal retina project to LGNd‐A and LGNd‐C; most project to SC, and about a third to PT. Beta cells, by contrast, project almost exclusively to LGNd‐A, with about 10% going to LGNd‐C, and about 1% to the PT. The great majority of epsilon cells, if not all, project to LGNd‐W, and up to half of this population also project to the other zones noted above. The remaining groups show little indication of branching, and separate to project, in varying proportions

ISSN:0092-7317    

DOI:10.1002/cne.902370206

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe distributions of peptide‐containing nerve fibers and cell bodies in the canine small intestine were determined with antibodies raised against seven peptides: enkephalin, gastrin‐releasing peptide (GRP), neuropeptide Y, neurotensin, somatostatin, substance P, and vasoactive intestinal peptide (VIP). Immunoreactive nerve cell bodies and fibers were found for each peptide except neurotensin. In the muscle layers there were numerous substance P, VIP, and enkephalin fibers, fewer neuropeptide Y fibers, and very few GRP or somatostatin fibers. The mucosa contained many VIP and substance P fibers, moderate numbers of neuropeptide Y, somatostatin, and GRP fibers and rare enkephalin fibers. Nerve cell bodies reactive for each of the six neural peptides were located in both the myenteric and submucous plexuses. The distributions of nerve cell bodies and processes in the canine small intestine show many similarities with other mammals, for example, in the distributions of VIP, substance P, neuropeptide Y, and somatostatin nerves. There are some major differences, such as the presence in dogs of numerous submucosal nerve cell bodies with enkephalinlike immunoreactivity and of GRP‐like immunoreactivity in submucous nerve cell bodies and mucosal f

ISSN:0092-7317    

DOI:10.1002/cne.902370207

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe retinal projection to the superficial pretectal parvicellular nucleus (SPp) of goldfish was examined by filling select groups of optic axons with cobaltous‐lysine. The tracer was applied intraocularly to peripheral retinal slits in some fish. In other fish, it was applied to optic axons from an intact hemiretina after one‐half of the retina was ablated and the corresponding optic axons had degenerated. The results indicated that SPp is a folded structure, having a dorsal surface innervated by axons from temporal retinal ganglion cells and a ventral surface innervated by axons from nasal retinal ganglion cells. Peripheral retina innervates the anterodorsal and anteroventral edges of SPp, while central retina innervates the posterior genu. Dorsal retina innervates lateral SPp and ventral retina innervates medial SPp. Thus, although SPp is a folded nucleus, the topography of the retino‐SPp projection is similar to the topography of the retinotectal projection. That is, the relative position of optic axons within SPp mirrors the retinal location of the ganglion cells that project to SPp. Retino‐SPp axons occupy the center of the main optic tract before it divides into the two optic brachia. These axons are topographically arranged, with temporal retino‐SPp axons being flanked on both sides by nasal retino‐SPp axons. Retino‐SPp axons arborize within SPp and then continue to enter the superficial tectal retinorecipient lamina. Thus, these axons innervate both SPp and the optic tectum. These findings are discussed with respect to chemospecific and morphogenetic views of visual syst

ISSN:0092-7317    

DOI:10.1002/cne.902370208

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractOrthograde axonal transport tracing methods were used to describe the projections to the basilar pontine nuclei (BPN) which arise within the face representation of motor or somatosensory cerebral cortex. Injections centered in motor face (MF) cortex resulted in the labeling of several corticopontine terminal fields which exhibit a rostrocaudal columnar arrangement within the ipsilateral BPN. The location of such terminal zones is consistent with the somatotopic pattern of termination previously described for limb sensorimotor cortices. In contrast, the projections from somatosensory face (SF) cortical regions largely terminate in BPN areas separate from those receiving either limb sensorimotor or MF inputs. Both MF and SF cortices also give rise to projections to the contralateral BPN; those from SF cortex are less extensive than those of MF origin.In addition to their relationship with limb sensorimotor corticopontine terminations, the MF projections to the BPN also seem to partially overlap the projection zones of the cerebellopontine system, particularly the regions projected upon by the lateral cerebellar nucleus. The SF projections, on the other hand, appear to terminate in BPN areas that also receive input from either the dorsal column nuclei or the spinal trigeminal complex. There is only minimal potential overlap between MF and SF projections in the BPN.With regard to the pontocerebellar system, the projections from MF cortex terminate among BPN neurons which project to the cerebellar hemispheres, particularly lobus simplex, crus I and crus II. The SF projections also overlap BPN neurons which project to the lateral hemispheres in addition to the paraflocculus and vermal lobules VII and IXa,b. Taken together these observations suggest that subsets of BPN neurons might exist such that some receive convergent inputs from systems whose function can generally be regarded as motor (sensorimotor cortex, cerebellopontine) while another population of BPN neurons might integrate signals from systems which transmit somatosensory information (dorsal column nuclei, spinal trigeminal).

ISSN:0092-7317    

DOI:10.1002/cne.902370209

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe immunohistochemical localizations of the enzymes glutamine synthetase, carbonic anhydrase‐C, and the intermediate filament protein GFA were examined for potential neuroglial specificity in the retinas of several types offish. Both glutamine synthetase and carbonic anhydrase‐C appear to be characteristic markers for retinal Müller cells. However, the horizontal neurons of most fish examined also possess high levels of carbonic anhydrase. Furthermore, GFA, the characteristic marker for fibrous astroglia in higher vertebrates, was found specifically localized in the horizontal neurons of several teleost fish. The identity of the GFA antigens was qualified by immunochemical as well as cytological examinations. Furthermore, specific antisera to other intermediate filament proteins, including neurofilaments, validated and contrasted with the observations made with antisera to GFA. The presence of GFA in horizontal neurons of fish is widespread but not typical of all fish. These observations indicate an evolutionary constancy of retinal Müller glial cells. However, these results again focus attention on whether horizontal cells are truly neurons or rather represent an intermediate cell type that may prove useful in studying the evolution, ontogeny, and functional significance of the neuronal‐glial phenotypic di

ISSN:0092-7317    

DOI:10.1002/cne.902370210

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe morphological development of the cochlea begins in the base or midbasal region and spreads toward the apex. In adults, the base responds maximally to high‐frequency sounds and lower frequencies are represented progressively toward the apex. This predicts that responses to sound should occur initially to high frequencies and gradually change to include lower frequencies. Paradoxically, animals respond first to relatively low frequencies and last to high frequencies.We have previously proposed that this discrepancy results from an ontogenetic change in spatial coding of frequency along the cochlea (Rubel et al., '76). According to this model, only the basal end of the cochlea transduces sound early in development but it responds to low frequencies. During maturation the representation of low and midrange frequencies shifts apically and the base becomes responsive to high frequencies, This hypothesis predicts that the tonotopic organization within the central nervous system should change during development; neurons at any given location within an auditory nucleus should become maximally responsive to successively higher frequency sounds during development.In the present study this prediction was tested by using microelectrode recording procedures to map the tonotopic organization of nucleus magnocellullaris (NM) and nucleus laminaris (NL), first‐ and second‐order auditory nuclei, in chickens at three ages: embryonic day 17, 1 day posthatch, and 2–4 weeks posthatch. The characteristic frequencies of neurons having the same anatomical location were quantitatively compared across ages.The tonotopic order in NM and NL was similar at all ages; responses to high‐frequency sounds were recorded anteromedially and lower frequencies were located progressively more caudolaterally. However, there was a striking quantitative change in tonotopic organization. Neurons at a given location in both nuclei became maximally responsive to progressively higher frequencies during development. The characteristic frequencies of neurons in embryos and newly hatched chicks averaged, respectively, 1.00 ((± 0.06, S.E.M.) and 0.34 (± 0.04) octaves lower than their predicted adult values. All regions in both nuclei showed a statistically significant increase in characteristic frequency during development except the most posterolateral (low‐frequency) sector. Too few neurons were recorded from this region to be able to reliably estimate characteristic frequency.These results support the hypothesis that the spatial coding of frequency along the cochlea shifts during development. This has three implications: (1) it helps explain the discrepancy between structural and functional develop‐ ment. (2) it suggests that all neurons will be maximally stimulated by low frequencies at some time during development. (3) it indicates that the values assigned to the place code are not fixe

ISSN:0092-7317    

DOI:10.1002/cne.902370211

出版商:Alan R. Liss, Inc.    

年代:1985

数据来源: WILEY