bluuebunny/crossref_metadata_2025 huggingface dataset:
The distribution of bovine pancreatic polypeptide/FMRFamide‐like immunoreactivity in the ventral nervous system of the locust
Authors: Myers Camilla M. , Evans Peter D.
Published: January 2005

The distribution of bovine pancreatic polypeptide (BPP) FMRFamide‐like immunoreactivity is described in the ganglia of the ventral nerve cord and in the peripheral median nervous system of the locust, Schistocerca gregaria.

Immunoreactive cell bodies occur in three regions of the thoracic ganglia: 1) two pairs of cells lie in the anterior of the ganglion ventral to the root of nerve 1 and the anterior ventral association centre; 2) a group of cells lies in the ventral midline at the level at which nerves 3 and 4 leave the ganglion; 3) and two bilaterally symmetrical, posterior lateral groups lie between nerves 5 and 6 at the edge of the ganglion. Immunoreactive cell bodies in the suboesophageal and abdominal ganglia are confined to the midline and are distributed along the anterior‐posterior axis both dorsally and ventrally. The processes of the posterior lateral groups have been traced into the neurohaemal organs of the median nerve and beyond. In the periphery such processes innervate the salivary glands and various muscles.

The nature of the endogenous antigen contained in the immunoreactive cells has been investigated with the use of antisera against other peptides of the pancreatic polypeptide family, namely avian pancreatic polypeptide, neuropeptide Y, and peptide YY. In addition, BPP antisera not specific for the C terminal hexapeptide have been tested. Liquid preabsorption experiments with BPP and FMRFamide (the molluscan cardioacceleratory peptide) suggest that the endogenous peptide antigen contained in the stained neurones may belong to the pancreatic polypeptide family or to the FMRFamide family.
An EM‐autoradiographic and EM‐HRP study of the commissural projection of the superior colliculus in the cat
Authors: Behan Mary
Published: January 2005

Terminals of the commissural projection in the cat were characterized ultrastructurally by autoradiograhic and horseradish peroxidase methods. The results of the two studies are complementary. Terminals of commissural cells are present in the intermediate and deep layers of the cat superior colliculus. Two distinct populations of terminals are present: one containing mostly round vesicles and forming asymmetric specializations, and a second containing mostly pleomorphic vesicles and forming symmetric specializations. Both populations contact small dendrites or dendritic appendages. The two populations, mostly round and mostly pleomorphic, are present in the ratio of 2:1. Terminals measure approximately 1.1 μm in mean diameter and contact profiles ranging in size from 0.2 to 4.6 μm. There is no significant difference between the two populations in either pre‐ or postsynaptic profile size. The colocalization of terminals of commissural neurons with other afferent and efferent projections of the intermediate layers of the superior colliculus is discussed.
The dendritic architecture of the visual pretectal nuclei of the rat: A study with the Golgi‐cox method
Authors: Gregory Kenneth M.
Published: January 2005

The dendritic architecture of the neurons of the visual pretectal nuclei in the rat was studied with the Golgi‐Cox method. The olivary pretectal nucleus (PO) is characterized by distinctive neurons with a gnarled, tufted, richly branched dendritic arbor forming a dense neuropil within the nucleus. The distinct dendritic morphology of the olivary pretectal neurons enables this nucleus to be identified at all levels of the pretectum in Golgi‐impregnated preparations. Rostromedially, the PO is surrounded by peripheral neurons whose dendrites wrap around the surface of the PO. The nucleus of the optic tract (NTO) contains three types of cells: (1) superficial horizontal cells whose dendrites extend out transversely; (2) large multipolar neurons whose dendrites spread out predominantly in a transverse plane, and (3) small to medium multipolar neurons with varying dendritic architecture. The posterior pretectal nucleus (PP) is composed predominantly of (1) multipolar cells with horizontally and vertically oriented dendrites extending out transverse to the optic axons; (2) piriform cells with dendrites extending dorsally toward the brachium; and (3) small multipolar neurons. The presence of superficial horizontal and large multipolar neurons in the NTO distinguishes the NTO from the PP in Golgi preparations. The horizontally oriented dendrites of many of the multipolar neurons in the PP give this nucleus an appearance distinct from that of the NTO. The differences in dendritic morphology between the visual pretectal nuclei in the rat permit identification of these nuclei at all levels within the pretectum. The boundaries of these nuclei, as determined in the Golgi‐Cox preparations, correlate quite well with the boundaries defined by studying retinal projections (Scalia and Arango, '79).
Immunohistochemical demonstration of some putative neurotransmitters in the lamprey spinal cord and spinal ganglia: 5‐hydroxytryptamine‐, tachykinin‐, and neuropeptide‐Y‐immunoreactive neurons and fibers
Authors: Van Dongen Paul A. M. , Hökfelt Tomas , Grillner Sten , Verhofstad Albert A. J. , Sternbusch Harry W. M. , Cuello A. Claudio , Terenius Lars
Published: January 2005

The distribution of some putative neurotransmitters was investigated in the spinal cord and spinal ganglia of the lamprey, a primitive vertebrate, by using immunohistochemical methods. In the spinal cord a midline row of 5‐hydroxytryptamine (5‐HT)‐immunoreactive neurons was present immediately ventral to‐the central canal over the entire length of the spinal cord. The ventral processes of these neurons formed a dense ventromedial plexus of varicosities. In the dorsal, lateral, and ventral spinal axon columns, several longitudinal 5‐HT fibers were present. After chronic spinal transections the distribution of 5‐HT fibers was unchanged; it is therefore concluded that there was no substantial descending 5‐HT contribution and that the spinal 5‐HT neurons supplied the regional 5‐HT innervation. The spinal 5‐HT cells sent fibers into the dorsal and ventral roots; 5‐HT cell bodies and fibers were also present in the spinal dorsal root ganglia, in their dorsal, ventral, and lateral nerve branches, and in the dorsal and ventral branches of the ventral roots.

Neurons and fibers containing peptides of the tachykinin (TK) family (to which, amongst others, substance P belongs) were found in the spinal cord. TK neurons in the spinal cord supplied the local TK innervation, as well as TK fibers in the dorsal and ventral roots. Fibers have been found containing either TK, or 5‐HT, or both compounds.

Neurons containing neuropeptide‐Y (NPY)‐immunoreactive material were present in a medial column just dorsal to the central canal. The NPY neurons have longitudinal, mainly descending, fibers that provide the local NPY innervation of the lamprey spinal cord.

The present results provide evidence for local spinal systems containing 5‐HT, TK, 5‐HT and TK, or NPY, but in contrast to mammals, these compounds do not seem to arise from supraspinal neurons.
The morphology of relay neurons in the dorsal lateral geniculate nucleus of the marsupial brush‐tailed possum (Trichosurus vulpecula)
Authors: Robinson Stephen R. , Webster Maree J.
Published: January 2005

The retinal terminal zones and the morphology of relay neurons within the dorsal lateral geniculate nucleus (LGNd) of the brush‐tailed possum (Trichosurus vulpecula) have been investigated with horseradish peroxidase (HRP) tracing techniques. Anterograde transport of HRP from the retina confirmed previous descriptions of the laminar distribution of retinal afferents in this nucleus. In addition, it was found that lamina III consists of two adjacent bands (IIIa and IIIb) of contralateral retinal input, separated by a terminal‐free zone 20–40 μm wide. This zone is not apparent with Nissl or fibre stains.

Relay neurons in the LGNd were retrogradely filled following cortical injections of HRP, and two classes (A and B) were distinguished. Class A neurons are found in the alpha portion of the LGNd (laminae I, II, III, and IV) and class B neurons in the beta portion (laminae V, VI, and VII). Class A cells are more densely packed and have shorter and more numerous dendrites, less‐extensive dendritic arbors, and thicker axons than class B cells. No significant differences were found between the two classes in perikaryal size or thickness of proximal dendrites. Neurons in each lamina of the nucleus have dendritic arbors which ramify extensively within adjacent laminae, except cells in lamina IIIb, which have relatively few dendrites that cross into the cell‐free zone and lamina IV.
The organization of retinal projections to the diencephalon and pretectum in the cichlid fish, Haplochromis burtoni
Authors: Presson Joelle , Fernald Russell D. , Max Marianna
Published: January 2005

The organization of retinofugal projections was studied in a cichlid fish by labelling small groups of retinal ganglion cell axons with either horseradish peroxidase or cobaltous lysine. Two major findings resulted from these experiments. First, optic tract axons show a greater degree of pathway diversity than was previously appreciated, and this pathway diversity is related to the target nuclei of groups of axons. The most striking example is the formation of the medial optic tract. Fibers that will become the medial optic tract move abruptly away from their neighbors, at about the level of the optic chiasm, and coalesce at the dorsomedial edge of the marginal optic tract. The medial optic tract projects to the thalamus, the dorsal pretectum, and the deep layer of the optic tectum. The axial optic tract is a group of fibers which segregates from the most medial portion of the marginal optic tract, at about the level of the optic chiasm. The axial tract stays medial to the marginal optic tract for a few hundred microns and then curves laterally to rejoin the marginal optic tract. At least some axial trat axons terminate in the suprachiasmatic nucleus. Within the marginal optic tract, retinal ganglion cell axons from a given retinal quadrant are always segregated into at least two groups. The smaller group projects to the superficial pretectal nucleus. The larger group projects to the superficial layer of the optic tectum.

Second, each nontectal retinal termination site receives a unique pattern of retinal input. Within the pretectum the parvocellular superficial pretectal nucleus receives a highly retinotopically organized input from all retinal regions; the basal optic nucleus receives a roughly retinotopically orgnaized input from all retinal regions; the dorsal pretectum receives an input from all retinal regions; and the central pretectal nucleus receives input only from the ventral hemiretina. Within the diencephalon the thalamus receives an input from all retinal regions, but this input is not retinotopically organized; the suprachiasmatic nucleus receives input from the region of central retina that lies just dorsal to the optic nerve head, via the axial optic tract. The accessory optic nucleus receives input from the dorsal hemiretina.
Heterogeneity of ganglia of the guinea pig myenteric plexus: An in vitro study of the origin of terminals within single ganglia using a covalently bound fluorescent retrograde tracer
Authors: Takaki Miyako , Wood Jackie D. , Gershon Michael D.
Published: January 2005

Experiments were done to test the hypothesis that individual ganglia of the myenteric plexus of the guinea pig small intestine are heterogeneous with respect to the location of the neurons that provide terminals to them. The myenteric plexus, attached to the longitudinal layer of smooth muscle, was maintained in vitro. Individual ganglia were injected with a variety of potential retrograde tracers by pressure microejection from the tip (20‐μm diameter) of a glass micropipette. The fluorescent dye 4‐acetoamido, 4′‐isothiocyanostilbene‐2,2′‐disulphonic acid (SITS) was found to be an effective tracer, labeling neuronal perikarya, evidently by retrograde transport. SITS has previously been shown not to cross plasma membranes, but to be covalently bound to the outer surface of that membrane, and to be taken up by nerve terminals to be retrogradely transported to label neuronal cell bodies. SITS fluorescence was found in about 12% of the neurons within the ganglion into which it was injected and also in approximately ten times more neurons in discretely located distant ganglia. No labeling of neurons was found when SITS was injected into the bath or into the smooth muscle below the myenteric plexus. Damage to neural connectives obstructed the labeling of neurons in ganglia distal to the injection site. Individual SITS‐injected myenteric ganglia were found to vary greatly in the ratios of intraganglionic SITS‐labeled neurons to the total number of neurons within the injected ganglion. The ratios of the number of intraganglionic SITS‐labeled neurons to SITS‐labeled neurons in distant ganglia projecting to the injected ganglion from elsewhere in the myenteric plexus also varied greatly. More strikingly, individual ganglia differed over a wide range with respect to whether the neurons in distant ganglia that provided them with terminals were situated in the oral, anal, or circumferential direction. Although the majority of projections were found to be from orally located ganglia, individual ganglia were observed that received predominantly or exclusively anal or oral projections. Others received mixtures of terminals from ganglia that were anal, oral, or circumferential. This anatomical heterogeneity in the location of afferent inputs to individual myenteric ganglia is probably reflected in a functional heterogeneity as well and will have to be taken into account in further studies of the physiology of the myenteric plexus. Individual ganglia of the plexus can no longer be taken as anatomically and functionally equivalent to one another.
Distribution of neuropeptide Y immunoreactivity in the basal forebrain and upper brainstem of the squirrel monkey (saimiri sciureus)
Authors: Smith Y. , Parent A. , Kerkérian L. , Pelletier G.
Published: January 2005

The distribution of neuropeptide Y (NPY) immunoreactivity in the brain of the squirrel monkey (Saimiri sciureus) was studied by means of the indirect immunofluorescence, peroxidase‐antiperoxidase, and avidin‐biotin‐complex methods. The antiserum used was raised in rabbits and did not show any significant crossreactivity with related peptides including peptide YY and avian pancreatic polypeptide.

In the upper brainstem of the squirrel monkey a dense NPY‐immunoreactive terminal field is seen in lateral parabrachial area, locus coeruleus, and interpeduncular nucleus. A small group of NPY‐immunoreactive cell bodies is present in the lateral habenula and a moderate number of NPY‐immunoreactive fibers occurs in periaqueductal gray and nucleus raphe pallidus. The substantia nigra (SN) appears mostly devoid of NPY immunoreactivity whereas the ventral tegmental area contains a few reactive fibers. In the hypothalamus the medial preoptic area as well as the arcuate and paraventricular nuclei receive a strikingly dense NPY innervation. In addition, numerous NPY‐positive cell bodies are found within the dorsomedial half of the supraoptic nucleus but very few are seen in paraventricular nucleus. A large number of NPY‐immunoreactive cell bodies is also present in arcuate nucleus. In the basal telencephalon NPY‐immunoreactive cells abound mostly in striatum, but some are also found in the amygdala (particularly basal, central, and lateral amygdaloid nuclei), the claustrum, and in the bed nucleus of the stria terminalis. Intensely reactive network of NPY‐immunoreactive fibers is also present in all of these structures. In striatum, the numerous, fine and nonvaricose NPY‐immunoreactive fibers, as well as the NPY‐positive cell bodies, are slightly more abundant in caudate nucleus than in putamen. The globus pallidus (GP) is mostly devoid of NPY‐immunoreactive fibers and terminals. The fact that the two major recipient structures of striatal outflow (SN and GP) do not receive significant NPY input suggests that the striatal NPY‐containing neurons are intrinsically organized.
Cytodifferentiation of photoreceptors in larval goldfish: Delayed maturation of rods
Authors: Raymond Pamela A.
Published: January 2005

This study describes the differentiation of photoreceptors in larval goldfish retina. The earliest photoreceptors to differentiate were cones; 3H‐fucose labeled cone but not rod outer segments in larval as well as adult goldfish. All major cone types known to be present in the adult goldfish retina (double cones, long and short single cones) were found in the larval retina by 2 days after hatching. The cones matured rapidly; within a few days they had well‐developed outer segments and synaptic pedicles that were smaller, but otherwise similar to those in adults. Rods were slower to mature. Their outer segments were at first short, wide, and misshapen; only as they grew longer and narrower did they become straight and properly aligned. Rod spherules were first seen in fish older than 1 month; immature rods contained perinuclear synaptic ribbons and invaginating processes penetrated the cell body. These results suggest that the influence of rods and cones on visual function in larval goldfish may be quite different from the adult.
The effects of a 30 day period of environmental diversity on well‐fed and previously undernourished rats: Neuronal and synaptic measures in the visual cortex (area 17)
Authors: Bhide P. G. , Bedi K. S.
Published: January 2005

Black and white Lister hooded rats were undernourished from the 16th day of gestation until 25 postnatal days of age. These previously undernourished rats and a set of well‐fed rats were later subjected to 30 days of environmental diversity, i.e., environmental enrichment or isolation. Two separate experiments were carried out. In experiment 1, the environmental diversity lasted from 85 to 115 days of age and in experiment 2, from 35 to 65 days of age.

At the end of the period of environmental diversity, all rats were killed by perfusion with 2% phosphate‐buffered glutaraldehyde. Small pieces of tissue from the right visual cortex were embedded in Spurr's resin. For each rat two blocks of resin‐embedded tissue were randomly selected, and from these semithin sections (0.5 μm) were cut and stained with toluidine blue. Photomicrographs of cortical layers II and III were taken from these sections and used to estimate the numerical density of neurons. Ultrathin (ca. 70 nm) sections of the same region of the cortex were cut and stained with lead citrate. These sections were used to estimate the synaptic disc diameter and numerical density. Synapse‐to‐neuron ratios were calculated from the estimates of synaptic and neuronal numerical densities.

In experiment 1, well‐fed rats raised in enriched environments had a significantly smaller neuronal numerical density and a greater synaptic disc diameter than well‐fed rats raised in an impoverished environment. In experiment 2, neither the well‐fed nor previously undernourished rats showed significant effects of environmental treatment on any of the features studied. The statistical interaction between nutrition and environment was not significant for any of the features in either experiment.
Topographical organization of the afferent connections of the principal ventromedial thalamic nucleus in the cat
Authors: Jiménez‐Castellanos J. , Reinoso‐Suárez F.
Published: January 2005

The afferent connections to the principal division of the ventromedial thalamic nucleus (VMP) were studied in the cat by means of the HRP retrograde transport technique. The large (40 nl) and small (20 nl) injections of this enzyme were delivered info the VMP using different stereotaxic approaches. The main afferents to VMP emanated bilaterally from the prefrontal, premotor, and rostral agranular insular cortices. Another important group of afferents to the VMP were those originating in the rostral third of the reticular thalamic nucleus, the entopeduncular nucleus, the substantia nigra pars reticulata, and the deep cerebellar nuclei. From the cerebellar nuclei, the contralateral lateral nucleus and the caudal third of both (ipsi and contralateral) medial cerebellar nuclei were the origin of afferents to the VMP. Other cortical areas projecting fin a lower density) to the VMP were the motor cortex, the cortex along the anterior ectosylvian sulcus, the granular insular cortex, the posterior agranular insular area, the prelimbic area, and the cortex along the posterior rhinal sulcus (SRP). Among other subcortical prosencephalic structures projecting to the VMP are the dorsal claustrum, substantia innominata, hypothalamic formations, and the zona incerta. Projections originated from the brainstem in the lateral part of the intermediate and deep layers of the superior colliculus, the central gray matter, the locus coeruleus, and the reticular formation. The nucleus tegmenti pedunculopontinus pars compacta, parabrachial nuclei, the vestibular complex, and the spinal trigeminal nucleus were also origins of projections to the VMP.

We conclude by emphasizing the important bilateral cortical modulation of the different functions attributed to the VMP: recruiting‐response mediation, reticular‐activating system participation, and extrapyramidal motor integration. In light of the connections just described, the VMP may be considered as a point for impulses coming from complex association cortical areas and limbic formations to converge with those emanating from cortical and subcortical motor structures.
A morphological investigation of thalamic neurons by intracellular hrp staining in cats
Authors: Yamamoto Tetsuro , Noda Terumi , Samejima Akio , Oka Hiroshi
Published: January 2005

Morphological analysis of 77 neurons in the ventroanterior (VA), ventrolateral (VL), ventromedial (VM), and central lateral (CL) nuclei was performed by intracellular HRP staining in combination with electrophysiological studies. The neurons were classified into four groups according to either electrophysiological or morphological criteria, i.e., 20 relay neurons 18 thalamocortical (T‐C) and two thalamocaudate (T‐Cd) relay neurons, 17 projection neurons, 36 unidentified neurons, and four presumed interneurons. All 36 unidentified neurons had morphological features similar to those of relay and projection neurons. All neurons except four presumed interneurons had dendrites sparsely covered with spinelike appendages. Most of their dendrites displayed a spherically radiating branching pattern, and a few showed a tufted or linearly oriented pattern.

Sizes of somata and dendritic radii were compared in entopeduncular (Ent)‐responsive (n = 25) and cerebellar (CN)‐responsive groups (n = 37) in VA, VL, and VM nuclei. The soma size was similar in VL (18–21 × 29–34 μm) and VM (15–19 × 29–31 μm), but in VA, CN‐responsive neurons (15 × 30 μm) seemed to be smaller than Ent‐responsive ones (22 × 36 μm). The largest dendritic field of neurons in each thalamic nucleus was similar in both groups. They were about 250–320 μm in radius. Diameters of axons were also compared but no statistically significant difference was detected (i.e., 1.5 ± 0.3 mean ± S.D.) μm for the Ent group and 1.7 ± 0.5 μm for the CN group.

Three types of axonal trajectories were noted, i.e., neurons projecting their axons dorsolaterally, ventrolaterally, or horizontally. Fourteen neurons out of 37 relay and projection neurons gave off several fine distal axon collaterals in the thalamic reticular nucleus, and one T‐Cd, three projection, and one unidentified neurons gave off proximal axon collaterals near the soma‐dendritic domain in addition to those in the thalamic reticular nucleus.

Four neurons classified as presumed interneurons had smaller somata (9–13 × 18–23 μm) and varicose dendrites. Three of them received Ent‐induced inhibitory postsynaptic potentials (IPSPs) or CN‐induced excitatory postsynaptic potentials (EPSPs). Several presumed axon terminals were found to cover the soma of an adjacent neuron, which seemed to indicate their inhibitory nature.

The proximal axon collaterals in the ventral thalamic nuclei may consist of local inhibitory circuits with presumed interneurons in addition to other inhibitory circuits with thalamic reticular neurons.
Cutaneous receptive fields of somatic and viscerosomatic neurones in the thoracic spinal cord of the cat
Authors: Cervero F. , Tattersall J. E. H.
Published: January 2005

Extracellular single‐unit recordings were made from 121 neurones in the thoracic spiral cord of the cat. All neurones could be driven by electrical stimulation of dorsal root afferent fibres. The neurones were classified, according to the absence or presence of inputs from the ipsilateral splanchnic nerve, as “somatic” or “viscerosomatic,” respectively.

Cutaneous receptive fields were identified for 75 of the neurones: 31 were somatic and 44 viscerosomatic. Only two of the somatic cells received cutaneous nociceptive inputs, compared with 33 of the viscerosomatic cells. Sixty‐four percent of the whole sample of neurones had receptive fields which included three or more dermatomes. Viscerosomatic cells tended to have larger receptive fields than the somatic neurones, and six of them had fields which did not include the corresponding (T11) dermatome.

Neurones with receptive fields in the dorsal one‐third of the dermatome tended to be located in the lateral one‐third of the dorsal horn, but those with receptive fields in the ventral two‐thirds of the dermatome showed no differential distribution within the gray matter. This is discussed with respect to the results of anatomical studies on the dorsal horn projections of cutaneous afferent fibres from different regions of the dermatome.

Preliminary results from intracellular staining with horseradish peroxidase reveal extensive branching of primary afferents in the dorsal horn, and large dendritic fields of dorsal horn neurones. Our physiological and morphological results indicate that the somatotopic organisation of the thoracic spinal cord is less well defined than that of the lumbosacral region.
The projection of the lateral geniculate nucleus to area 18
Authors: Geisert Eldon E.
Published: January 2005

The present study is concerned with the projection of the lateral geniculate nucleus onto cortical area 18. Horseradish peroxidase (HRP) was injected into area 18 of 15 cats. Drawings were made to determine the location of the injection site and the distribution of labeled neurons in the lateral geniculate nuclei of each cat. The local retinotopic maps constructed prior to the injections and the reconstructions of the lateral geniculate nucleus were used to determine the location and the extent of each of the HRP injections.

In 15 of the 25 hemispheres studied, the ratio of the number of HRP‐labeled neurons in lamina A relative to the number of labeled neurons in lamina A1 was calculated. This ratio varied from 1.06 to 0.28, indicating that at least some regions of area 18 are dominated by inputs from lamina A1. However, if the HRP‐labeled neurons in lamina C are included in the counts for lamina A, then the ratio A + C/A1 has a mean of 1.11, suggesting that area 18 receives a balanced input, with inputs from the contralateral eye being relayed through laminae A and C, and inputs from the ipsilateral eye being relayed through lamina A1.

When the distribution of HRP‐labeled neurons in lamina A was plotted onto a dorsal view of the lateral geniculate nucleus, the labeled neurons formed an ellipse with the long axis of the ellipse oriented parallel to the isoelevation lines. The representation of azimuth is compressed in area 18 relative to the lateral geniculate nucleus.

In six hemispheres the injections were restricted to a few layers of the area 18. Following small injections into layer IV of area 18, the HRP‐labeled neurons occupied an extensive region of the lateral geniculate nucleus, indicating a considerable amount of convergence of the inputs to area 18. In hemispheres where the injections were restricted to layers I and II, labeled neurons were only seen in the medial interlaminar nucleus and the C laminae.
Postnatal development of 3H‐GABA‐ accumulating cells in rabbit retina
Authors: Redburn Dianna A. , Madtes Paul
Published: January 2005

Light and electron microscopic autoradiography demonstrates that 3H‐GABA is accumulated by horizontal cells in neonatal rabbit retina but not in the adult. A specific population of horizontal cells appears to be mature at birth and they avidly accumulate 3H‐GABA during a 15‐minute incubation period in vitro. Uptake into horizontal cells is not observed after the fifth postnatal day; 3H‐GABA‐accumulating horizontal cell bodies and their processes are the first identifiable components that clearly mark the future location of the outer plexiform layer at birth and as such, may be considered pioneering elements. Our observations raise the interesting possibility that the pioneering horizontal cell may provide structural and/or chemical factors necessary for the subsequent development of the outer plexiform layer of the retina.

Labeling patterns of other retinal cells also show varying degrees of change during development. (1) A population of amacrine cells accumulate 3H‐GABA at birth. These cells show little change in their morphological or 3H‐GABA uptake properties from birth to adulthood. (2) Müller cells show weak accumulation of 3H‐GABA at birth. Subsequent to this time, labeling of Müller cells is significantly more robust, resulting in Müller cell domination of retinal autoradiographic patterns in more mature retinas. (3) Every cell body in the ganglion cell layer accumulates 3H‐GABA at birth. The number of labeled cells declines during postnatal development, resulting in a very limited adult population. We conclude that the ability of retinal cells to accumulate 3H‐GABA does not remain constant during postnatal development; rather each cell population displays a unique maturation sequence that results in a dramatic developmental shift in the number and types of GABA‐accumulating cells present in the retina.
Neurogenesis in reptilian cortical structures: 3H‐thymidine autoradiographic analysis
Authors: Goffinet A. M. , Daumerie Ch. , Langerwerf B. , Pieau C.
Published: January 2005

Histogenesis was studied in forebrain cortical areas of two reptiles, Emys orbicularis and Lacerta trilineata, by using tritiated thymidine autoradiography. Four areas were considered: the dorsomedial, the general (dorsal), and the lateral cortices, and the dorsal ventricular ridge (DVR). The bulk of neurogenesis in these four pallial fields proceeds within a short period of 8‐9 days, between developmental stages 15 and 18 in Emys and stages 32‐34 in Lacerta. Lateral‐to‐medial as well as anterior‐to‐posterior tangential gradients of histogenesis are present in both species. Radial neurogenetic gradients are directed from outside to inside, except in the medial cortex of lizards, where no radial gradient is seen. This pattern of histogenesis in the cortex of turtles and lizards is comparable to that in mammals in terms of timing and tangential, areal variations. It might represent a “common denominator” of cortical histogenesis. However, in contrast to the mammalian cortex, which develops according to an inside to outside, “inverted” pattern, radial neurogenesis in the cortex of turtles and lizards follows an outside‐to‐inside gradient. These observations suggest that the inside‐out gradient of cortical neurogenesis has been acquired during evolution of the synapsid radiation from stem reptiles to mammals, and that it may be related to the development of radial cortical architectonics.
Selective cytochemical demonstration of glycoconjugate‐containing terminal N‐acetylgalactosamine on some brain neurons
Authors: Nakagawa Fukuo , Schulte Bradley A. , Spicer Samuel S.
Published: January 2005

Paraffin embedded sections of rat, mouse, dog, and human brain were stained with a battery of lectin‐horseradish perioxidase conjugates to localize and characterize glycoconjugates. In the rat and mouse cerebral cortex, a subpopulation of nonpyramidal neurons stained selectively with three lectins with specific affinity for terminal N‐acetylgalactosamine (GalNAc). These and only these lectins stained the surface of the cell body, dendritic shafts, and proximal parts of the dendritic arborization. Most reactive, nonpyramidal neurons revealed a multipolar dendritic pattern, but some possibly belonged to the bitufted and bipolar types of neuron. The GalNAc‐containing neurons appeared widely distributed in layers II–VI with relatively greater abundance in layers IV and V. In the cortex of rats and mice the stained neurons occurred in moderate numbers in the frontal, frontoparietal, striate, retrosplenial, and entorhinal regions, but were less numerous in the hippocampal gyrus, dentate gyrus, and olfactory area. Other neurons in the basal ganglia and brain stem stained weakly for GalNAc. Examination of the frontal cortex of human and canine brains showed a similar distribution of nonpyramidal neurons with affinity for GalNAc‐binding lectins. At high magnification, the surface staining of neurons in the cerebral cortex, deep cerebellar nucleus, and other sites appeared periodic rather than continuous. The periodic character of the neuronal surface staining suggested a location for the reactive glycoconjugate in or between the synapses. The GalNAc‐containing glycoconjugate occurred in a selected cell type, failed to bind the other lectin conjugates, and differed from biochemically detected glycoconjugates. It is, therefore, considered a newly recognized entity of possible physiologic significance for a population of cortical neurons.
Neurotensinlike immunoreactive neurons in the hedgehog (Erinaceus europaeus) and the sheep (Ovis aries) central nervous system
Authors: Papadopoulos G. C. , Karamanlidis A. N. , Antonopoulos J. , Dinopoulos A.
Published: January 2005

Neurotensin‐containing neurons in the hedgehog and sheep central nervous system were studied immunohistochemically. In both species, mapping of neurotensin neurons was achieved only after pretreatment with colchicine injected intracerebroventricularly 2 days prior to perfusion. Bipolar or multipolar neurotensin neurons, 10–30 μm in diameter, were observed in the following regions of the central nervous system of both species: medial amygdaloid nucleus, lateral septal nucleus, interstitial nucleus of the stria terminals, caudate nucleus, preoptic area, and hypothalamus. On the contrary, while immunoreactive neurons were found in the central amygdaloid nucleus, nucleus accumbens, nucleus of the diagonal band, subthalamus, superior central nucleus, dorsal raphe nucleus, central gray substance of the pons, and dorsal horn of the spinal cord of the hedgehog, respective regions of the sheep appeared to be devoid of immunoreactive perikarya. Also, in some regions, namely the hippocampal formation, the central gray substance of the midbrain, the locus coeruleus, and the nucleus of the solitary tract, neurotensin neurons were found exclusively in the latter species.

The existence of these differences in the distribution pattern of neurotensin‐immunoreactive neurons between the two species as well as between them and others already examined is briefly discussed.
Stellate cell development in the frog cerebellum during spontaneous and thyroxin‐induced metamorphosis
Authors: Hauser Kurt F. , Uray Nándor J. , Gona Amos G.
Published: January 2005

Stellate cell development was studied in the bullfrog cerebellum during spontaneous and thyroxin‐induced metamorphosis using the Golgi‐Kopsch method and electron microscopy. Cells that possessed axosomatic synapses and resembled stellate cells were present even in the incipient molecular layer of the cerebellum in the premetamorphic tadpole. These cells may have originated from the early, transient wave of external granule cells that have been reported in the cerebellum of premetamorphic tadpoles in the first 6 months of development, and may constitute the variant population of stellate cells that are present later during development or the degenerating cells that have been observed during metamorphosis as scattered dying cells in the molecular layer.

Typical stellate cells, whose development resembled the genesis and differentiation of stellate cells in birds and mammals, were initially observed at the outer border of the molecular layer that is adjacent to the external granular layer during the onset of metamorphosis. These stellate cells were bipolar with processes extending in a plane perpendicular to elongating parallel fibers, and with progressive development, became multipolar with dendrites oriented in various directions with respect to the pia. Stellate cell axons innervate the dendrites and somata of Purkinje cells and other stellate cells, and can be categorized into two types: (1) axons with extensive branching near the soma of origin, and (2) long axons with few branches that occasionally terminate in the Purkinje cell layer. Atypical neurons that did not resemble typical stellate cells were also present in the molecular layer; these might be classified as a stellate cell variant.

The generation and differentiation of stellate cells can be‐induced 1 to 2 years prematurely by administering thyroid hormone to premetamorphic tadpoles. Like most events of cerebellar histogenesis in the frog, stellate cell development also appears to be largely a thyroid‐dependent phenomenon.
Rostrocaudal differences in dendritic growth and synaptogenesis in rat sympathetic chain ganglia
Authors: Snider William D.
Published: January 2005

Vertebrate embryos show a rostral to caudal gradient of morphogenesis. I have investigated the effect of this developmental gradient on neuronal maturation and synapse formation by comparing the development of rostral and caudal sympathetic chain ganglia in the rat. In young adults the superior cervical and lumbar ganglia are almost identical in terms of neuronal morphology and quantitative aspects of innervation. In neonates, however, substantial rostrocaudal differences are apparent in dendritic complexity, number of axons innervating ganglion cells, and synaptic density. There is an associated delay in ganglion cell‐target interactions in the lumbar region.

My results show that rostrocaudal position is significantly correlated with the time course of dendritic growth and synaptogenesis and suggest that ganglion cell‐target interactions may be important in these developmental processes. This difference in developmental rate, however, does not lead to differences in neuronal morphology or synaptic density between rostral and caudal ganglia in maturity.
The projections from striate cortex (V1) to areas V2 and V3 in the macaque monkey: Asymmetries, areal boundaries, and patchy connections
Authors: Van Essen D. C. , Newsome W. T. , Maunsell J. H. R. , Bixby J. L.
Published: January 2005

The organization of projections from V1 to areas V2 and V3 in the macaque monkey was studied with a combination of anatomical tecniques, including lesions and tracer injections made in different portions of V1 and V2 in 20 experimental hemispheres. Our results indicate that dorsal V1 (representing the inferior contralateral visual quadrant) consistently projects in topographically organized fashion to V3 in the lunate and parietooccipital sulci as well as to the middle temporal area (MT) and dorsal V2. In contrast, ventral V1 (representing the superior contralateral quadrant) projects only to MT and ventral V2. A corresponding dorsoventral asymmetry in myeloarchitecture supports the idea that V3 is an area that is restricted to dorsal extrastriate cortex and lacks a complete representation of the visual field. The average surface area of myeloarchitectonically identified V3 was 89 mm2. Additional information was obtained concerning the laminar distribution of connections from V1 to V2 and V3, the patchiness of these projections, and the consistency of projections to other extrastriate areas, including V4 and V3A.
Morphological evidence for the existence of multiple neuronal classes in the cat lateral superior olivary nucleus
Authors: Helfert Robert H. , Schwartz Ilsa R.
Published: January 2005

This study characterizes morphologically the neurons residing within the matrix of the cat lateral superior olive (LSO), excluding the hili and myelinated axon envelope. Several light microscopic techniques including Golgi impregnations, Nissl stains, and acetylcholinesterase histochemistry were used, as well as electron microscopy. Five distinct classes of neurons have been identified: principal neurons, multiplanar neurons, marginal neurons, small neurons, and class 5 neurons. These neuronal classes differ in regard to their size and shape, dendritic organization, perikaryal synaptic density, and their relative numbers.

Principal neurons compose approximately three‐quarters of the LSO neurons. They are multipolar and uniplanar in their dendritic arborization, radiating from the hili in rostrocaudal planes perpendicular to the curvatures of the LSO. In transverse sections the principal cell perikarya are fusiform and bipolar, with mean dimensions of 23 × 11 μm. More than 60% of the surface of these cells is contacted by synaptic terminals. Multiplanar neurons (averaging 23 × 19 μm) compose only 11% of the LSO neuronal population. Their dendritic arborization is not restricted to any particular plane, and their somal surface receives synaptic contacts similar, in number and type, to principal cells. Marginal neurons, although they are similar to principal neurons in shape and dendritic arborization, differ in that they are generally smaller (averaging 20 × 10.5 μm). They also possess fewer axosomatic synaptic contacts (− 33%), are oriented perpendicularly to principal neurons, are limited in distribution to the contours of the LSO immediately beneath the myelinated axon envelope, and constitute only 4% of the neuronal population. Small neurons (mean dimensions = 9 × 8 μm) compose 8% of the LSO neurons. They possess a multiplanar array of primary dendrites and have nuclei with multiple deep infoldings. Small neurons have the fewest axosomatic synaptic contacts of all classes of LSO neurons (−10%). Additionally, there are neurons that are similar to principal neurons, but receive fewer axosomatic contacts (− 33%). These cells have been tentatively identified as class 5 neurons until more information on this type allcws for the assignment of a more descriptive name. A number of acetyleholinesterase‐positive neurons are also found within the LSO, whose relationship to the other classes of neurons is presently unresolved. Possible functions of the multiple neuronal types are discussed.
Relationship of ocular pigmentation to the boundaries of dorsal and ventral retina in a nonmammalian vertebrate
Authors: Springer Alan D. , Mednick Adam S.
Published: January 2005

The goldfish eye and retina are partitioned traditionally into dorsal and ventral sectors by a horizontal meridian that passes through the optic disc and is perpendicular to a vertical meridian that extends from the remnant of the choroid fissure through the optic disc. Axons of retinal ganglion cells (RGCs) situated above the horizontal meridian are thought to reach the optic tectum via the ventrolateral optic tract and axons of RGCs situated below the horizontal meridian are thought to reach the optic tectum via the dorsomedial optic tract. When cobaltous‐lysine was applied to small temporal retinal slits that were centered on the traditional horizontal meridian, filled fibers were found in the dorsomedial, but not in the ventrolateral, optic tract (Springer and Mednick, '83). Since cobalt‐filled axons should have been found in both optic tracts, the traditional horizontal meridian does not indicate the actual boundary between dorsal and ventral retina. We report here that the goldfish iris contains nasal and temporal pigmentation lines (darts) that are each located approximately 21° above the traditional horizontal retinal meridian. Cobalt applied to retinal slits located just above the darts filled RGC axons in the ventrolateral optic tract and cobalt applied to retinal slits just below the, darts filled RGC axons in the dorsomedial optic tract. Converging evidence for the reliability of the darts as indicators of the boundary between dorsal and ventral retina was obtained by applying cobalt to severed RGC axons along the dorsomedial edge of the tectum. Cobaltfilled RGCs were found below the nasal dart. The irideal darts may be useful for standardizing electrophysiological retinotectal maps across subjects and laboratories. They will also be useful for elucidating the different trajectories of dorsal and ventral RGC axons, as well as their transformations within the visual pathways.
Synaptic organization of the cone horizontal cells in the catfish retina
Authors: Sakai Hiroko M. , Naka Ken‐Ichi
Published: January 2005

Horizontal cells of the vertebrate retina are known to contribute to the formation of the receptive fields surrounds photoreceptor and biopolar cells. However, few synapses have bee describe anatomically that might mediate these interactions. We have observed in the catfish retina that cone horizontal cell perikarya and dentrites make‐conventional chemical synapses onto photoreceptor terminal telodendria and, onto bipolar cell dendrites, while horizontal cell axon terminals make chemical synapses onto the perikarya and processes of amacrine cells. The synapses are characterized by clusters of round vesicles aggregated close to the site of contact, as well as by electron‐dense material associated with both pre‐ and postsynaptic membranes. The three kinds of synapses observed anatomically correspond to the synaptic pathways involving cone horizontal cells that have been suggested by the physiology of these cells.
A quantitative morphological study of interstrain variation in the developing rat optic nerve
Authors: Hunter A. , Bedi K. S.
Published: January 2005

Groups of pigmented (Black and White Hooded Lister) and albino (Sprague Dawley) rats were killed at 7, 15, and 25 postnatal days of age. Their optic nerves were embedded in resin suitable for both light and electron microscopy. Quantitative stereological procedures were used to estimate total fibre number and the degree of myelination in the optic nerves at the various ages.

At 7 days of age, both albino and pigmented rats had about 220,000 optic nerve fibres. By 15 days, both strains showed a reduction of some 30,000 fibres. This fibre loss continued in both strains after 15 days of age, but more rapidly in the pigmented strain. At 25 days of age, pigmented rats had 72,371 ± 7,244 fibres, whilst albino rats had 102,681 ± 4,138 fibres (P <01). More than 99.5% of optic nerve axons in both strains were unmyelifiated at 7 days of age. By 25 days of age about 90% of all remaining fibres were myelinated in both strains.

The mean diameter of the myelinated axons was estimated to be between 0.59 and 0.65 μm in all animals, there being no significant age or strain differences.

In contrast, the mean diameter of nonmyelinated axons increased significantly with age. This increase was greater for albino than pigmented rats, such that by 25 days of age the respective values were 0.49 μm and 0.42 μm (P < .05).