摘要:

AbstractThe goal of thin study was to define the detailed cytoarchitecture of the medulla oblongata of the rat in order to accurately localize immunocytochemically distinct populations of neurons in this region. The cytoarchitectonic features of this region of the rat brain stem were examined in 40 μm thick serial sections of celloidin embedded brains blocked in the Horsley‐Clarke stereotaxic plane. These sections were stained with cresyl violet and examined at a number of different magnifications with a variety of different intensities of staining to demonstrate particular features of the cells in this region. High magnification photomicrographs of this material revealed characteristic features of the various populations of cells.The results illustrate that the cytoarchitecture of the medulla oblongata of the rat changes remarkably within very short distances in the rostrocaudal direction. These changes indicate the need to study the anatomy and immunocytochemistry of this region in detailed serial sections. The ventral reticular formation of the rat medulla is cytoarchitectonically complex. Nuclear groups such as the lateral reticular nucleus (LRt) contain a number of cytoarchitectonically distinct subnuclei, as does the dorsally located nucleus of the tractus solitarious (nTS) (Kalia and Sullivan, '82). These nuclei occupy a considerable length of the medulla and terminate abruptly at the pontomedullary boundary. A number of other cytoarchitectonic features of the medulla were examined and the detailed characteristics were defin

ISSN:0092-7317    

DOI:10.1002/cne.902330302

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe aim of this study was to determine the anatomical relationships between catecholaminergic neurons and cytoarchitectonically defined nuclei in the caudal medulla oblongata. Previous studies have demonstrated the existence of noradrenergic cell bodies (designated as the A1 and A2 cell groups) in the caudal medulla oblongata of the rat (Dahlström and Fuxe, '64), including the nTS. There, is no information currently available with regard to details of the distribution of these noradrenergic neurons in the functionally distinct subnuclei of the medulla oblongata. In this study the location of catecholamine‐synthesizing enzymes was examined in the serial sections of the caudal medulla oblongata of the rat: tyrosine hydroxylase (TH), dopamine‐beta‐hydroxylase (DBH), and phenylethanolamine N‐methyl transferase (PNMT). The immunoperoxidase method of Sternberger ('79) was used to demonstrate the location of immunoreactive neurons, nerve fibers, and presumptive terminal processes. This was followed by Nissl staining of the same sections to localize accurately the immunoreactivity.Noradrenergic neurons (TH‐ and DBH‐positive and PNMT‐negative) were localized in a number of subnuclei of the nucleus of the tractus solitarius (nTS), the area postrema (ap), and in the dorsal motor nucleus of the vagus (dmnX). The distribution of these noradrenergic cells was different at different rostrocaudal levels. In addition,adrenergicneurone (TH‐, DBH‐, and PMNT‐positive) were identified dorsal to the tractus solitarius (TS), in the dorsal strip region (ds), the periventricular region (PVR), the dorsal parasolitarius region (dPSR), and the dmnX (rostral to obex). In addition,dopaminergicneurons (TH‐positive and DBH‐ and PNMT‐negative) were found in the ap and dmnX. The A1 cell group in the ventrolateral medulla consisted almost exclusively of noradrenergic neurons (TH‐ and DBH‐positive and PNMT‐negative).These results indicate that in the rat the A2 cell group is a mixed population of catecholaminergic neurons that are localized in well‐defined regions of the dorsal medulla oblongata. The distribution of these neurons is very specific both in terms of rostrocaudal levels and cytoarchitectonic subdivisions of regions of the medulla known to be involved in central autonomic control. This supports the hypothesis that monoaminergic neurons in the dorsal medulla play important roles in the centr

ISSN:0092-7317    

DOI:10.1002/cne.902330303

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe goal of this study was to define the cytoarchitectonic relationships between the catecholaminergic cell groups (the C1 and C2) in the rostral medulla oblongata of the rat. Immunocytochemistry was combined with Nissl staining to determine the nuclear boundaries in this region of the brain stem. In addition, the morphological characteristics of neurons in the C1 and C2 cell groups were determined and the relationship between these populations of neurons and their caudaul counterparts (A1 and A2 cell groups) was established (Kalia et al., '85a).The results indicate that the C1 and C2 cell groups are distributed over a wide region of the rostral medulla. The location of these adrenergic neurons is related to a number of nuclear groups in this region. This finding was remarkably consistent in all the animals studied in this series. In addition, adrenergic nerve fibers were found to be distributed over a large region of the medullary reticular formation. There was homogeneity in the morphology of the C1 and C2 cell groups. These rostrally located adrenergic neurons did not share morphological features in common with the recently described (Kalia et al., '85a) caudally located adrenergic neurons in the dorsal region of the nucleus of the tractus solitarius. These striking anatomical features of the adrenergic C1 and C2 cell groups support the proposal that adrenergic neurons in the rostral medulla oblongata play an important role in the integration of visceral functions (Fuxe et al., '80).

ISSN:0092-7317    

DOI:10.1002/cne.902330304

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

年代:1985

数据来源: WILEY

摘要:

AbstractWe examined serial 40 μm vibratome, immunoperoxidase‐stained sections of the medulla with tyrosine hydroxylase (TH), dopamine‐beta‐hydroxylase (DBH), and phenylethanolamine N‐methyltransferase (CPNMT) antisera followed by Nissl staining to locate catecholaminergic neurons in cytoarchitectonic regions followed by a three‐dimensional (3D) computer reconstruction of these cell groups to determine their spatial organization. Overlay drawings of low and high power photomicrographs showing cell bodies and nuclear boundaries were entered into a digital computer storage system. Every section in the series was plotted to yield an accurate representation of regional densities of cells and location of nuclei, as revealed by two‐dimensional plots of individual sections as well as three‐dimensional plots of groups of sections. Data files were scanned in a number of ways to obtain total cell counts of TH‐, DBH‐, and PNMT‐immunoreactive cells within a designated area or cell counts of only one type of immunoreactive cell. This combination of data manipulation produced the following results: (1)A1 groupis a homogeneous population of noradrenergic neurons at levels caudal to the obex, and at the obex it is mixed with adrenergic cells. The dimensions of the A1 cell group are 1.3 × 2.7 mm, extending from −2.5 to +0.2. Part of this cell group lies in the lateral reticular nucleus. (2)A2 groupis not purely noradrenergic as previously suspected. It is a very mixed cell group containing mainly dopaminergic neurons in the area postrema (periventricular region) and the dorsal motor nucleus of the vagus, mainly noradrenergic neurons in the medial subnucleus of the nucleus of the tractus solitarius (nTS), mainly adrenergic neurons in the dorsal strip and dorsal subnucleus of the nucleus of the tractus solitarius, and a mixture of all three catecholaminergic neurons in the other subnuclei of the nTS. The dimensions of this group are 0.4 × 3 mm extending from −2.7 to +0.3. (3)C1 groupis a homogeneous population of adrenaline cells extending from +1 to +2.5 with dimensions of 1.5 × 1.5 mm and consisting of scattered neurons some of which occupy the gigantocellular reticular nucleus. (4)C2 groupis a homogeneous population of adrenaline neurons extending from +1 to +3 with dimensions of 2.5 × 3 mm. Accurate visual imaging and quantitation of the spatial organization of medullary catecholaminergic neurons within the classical anatomical framework of cytoarchitecture provides an enhanced comprehension of the organization of this region o

ISSN:0092-7317    

DOI:10.1002/cne.902330305

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

年代:1985

数据来源: WILEY

摘要:

AbstractWe describe a class of reticular neurons, named T interneurons after the branching pattern of their axons, in young larvae of the zebrafishBrachydanio rerio.The cells were identified by filling them with HRP from application sites within the CNS. A serially repeating set of about ten such neurons is present in a longitudinal column on each side of the caudal hindbrain. The T axons project across the midline, and branches course both rostrally and caudally within the medial longitudinal fascicle (mlf). The cells receive synaptic input from the Mauthner neurons, from unidentified axons in the mlf, and perhaps from trigeminal sensory fibers. They project to cranial and pectoral motor nuclei.T interneurons appear to be homologous to giant fiber neurons in the hatchetfish and to some of the cranial relay neurons in the goldfish. We discuss a possible functional role and comparative implications of their distribution in the hindbrain.

ISSN:0092-7317    

DOI:10.1002/cne.902330306

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

年代:1985

数据来源: WILEY

摘要:

AbstractWe studied the anatomy of neuromasts, afferent sensory neurons, and efferent neurons of the midbody branch of the posterior lateral line in larvae of the zebrafish (Brachydanio rerio), 5 days after fertilization. This simple sensory system consists often or 11 neuromasts, 15–20 sensory neurons, and about nine efferent neurons. The neuromasts are typical free neuromasts and both afferent and efferent synapses are present on hair cells within them. The sensory neurons project into a single longitudinal column of neuropil in the hindbrain. The sensory terminals appear by light microscopy to contact the dorsolateral dendrite of the ipsilateral Mauthner cell. Three types of efferent neurons are present; two types in the hindbrain and one type in the diencephalon. We provide several lines of evidence that demonstrate that these central neurons are efferent to the lateral line.We conclude from this morphology that the larval system includes all of the components of the adult system and is probably functional at this early stage. We also found that larvae have all of the efferent neurons found in adult zebrafish, while the number of neuromasts and sensory neurons will increase during subsequent developmen

ISSN:0092-7317    

DOI:10.1002/cne.902330307

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe responses of 65 cells to electrical stimulation of the contralateral optic nerve were intracellularly recorded in the pigeon optic tectum by using micropipettes filled with a solution of horseradish peroxidase. Nineteen of them were successfully labeled. Microscopic examination of the filled cells shows that our sample includes six pyramidal, ten ganglion, two stellate, and one, bipolar horizontal cells. Thus, pyramidal and ganglion neurons constitute the most numerous types of cells in our sample. Pyramidal cells were located in layer II but mostly in its non‐retinorecipient part, and they had restricted ascending dendritic trees oriented orthogonal to the tectal lamination. Ganglion cells were located in layer in with one exception, which was in sublayer IIi. These cells had non‐oriented dendritic trees which ramify over considerable distances. Terminal dendritic branches from a number of pyramidal and ganglion cells extended superficially well within the region of optic fibers termination. In our study, ganglion cells constituted the efferent tectal elements. Pyramidal cells responded to optic nerve stimulation with a pure EPSP, with an EPSP‐IPSP sequence, or with a pure IPSP. Ganglion cells always exhibited an IPSP either alone or preceded by an EPSP. Stellate and bipolar cells responded with a pure EPSP. The study of the laminar distribution of labeled and non‐labeled cells shows from surface to depth, a gradual increase in the number of cells responding with an EPSP‐IPSP or with a pure IPSP and a gradual decrease in the number of those exhibiting a pure EPSP. The analysis of the sensitivity of EPSPs and IPSPs to high frequency optic nerve stimulation shows that (1) monosynaptic as well as polysynaptic EPSPs can be recorded from cells in the non‐retinorecipient tectal region, (2) a number of ganglion and pyramidal cells receive a direct retinal excitatory input as their dendrites pass through the region of optic endings, (3) most IPSPs are polysynaptic, (4) some cells located in the retinorecipient region may receive direct retinal inhibitory

ISSN:0092-7317    

DOI:10.1002/cne.902330308

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

年代:1985

数据来源: WILEY

摘要:

AbstractPostnatal development of axosomatic synapses was studied in the rat visual cortex in order to obtain experimental data that may explain how the unequal distribution of asymmetric and symmetric synapses evolves on the soma of cortical neurons. Three types of synaptic junctions were identified: (1) asymmetric or type 1 synapses, with postsynaptic densities ≥ 20 nm, (2) symmetric type 2 synapses, and (3) symmetric synapses with an intermediate structure. The third synapse type had a structure similar to that of type 1 synapses, although the postsynaptic densities were thinner than 20 nm.Type 1 synapses developed in three phases. In phase 1, the first postnatal week, there were many free postsynaptic thickenings and immature synapses whereby a higher degree of postsynaptic differentiation was visible in comparison to the presynaptic elements. During the following 10 days, phase 2, type 1 synapses containing thin postsynaptic densities and intermediate synapses temporarily increased in number. Intermediate synapses are interpreted as precursors of type 1 synapses that have relatively immature postsynaptic elements. Toward the end of synaptogenesis, phase 3, the free postsynaptic thickenings reappeared while type 1 synapses containing well developed postsynaptic elements prevailed. Throughout the whole postnatal period, the numerical density of axosomatic type 1 synapses remained very low and the ratio of asymmetric to symmetric synapses at the neuronal somata was inversely proportional to that at the dendrites. Also, there was a significant decrease in the numerical density of type 1 synapses between postnatal days (P) 17 and 30. Data normalized according to cortical growth suggest that this is probably due to a decrease in the number of axosomatic type 1 synapses. This corresponds to the observation that in layers III and V a few type 1 synapses were found on pyramid‐like cells up to P10 which then disappeared in later stages.Axosomatic type 2 synapses appear to be formed by two different presynaptic processes. The first presynaptic type contains flocculent material with glycogen granules and resembles axonal growth cones. These junctions contain multiple adhesion patches, intermediate junctions, one or more active zones, narrow synaptic clefts, and small pleomorphic vesicles. All of these are structural features of adult type 2 synapses. The growth‐cone‐like presynaptic elements disappeared after about 3 weeks. The second presynaptic type is smaller in size and also forms contacts with a structure similar to adult type 2 synapses. During the first postnatal week, the numerical density of symmetrical synapses (including intermediate synapses) was very low and increased more or less at a regular pace until P55. These data suggest that during postnatal development fewer type 1 synapses are formed on the somata than in the surrounding neuropil, and there was an additional reduction in the number of axosomatic type 1 synapses during the third and fourth postnat

ISSN:0092-7317    

DOI:10.1002/cne.902330309

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

年代:1985

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902330301

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

年代:1985

数据来源: WILEY