bluuebunny/crossref_metadata_2025 huggingface dataset:
Central distribution of efferent and afferent components of the pudendal nerve in macaque monkeys
Authors: Ueyama Teizo , Mizuno Noboru , Takahashi Osamu , Nomura Sakashi , Arakawa Hisao , Matsushima Ryotaro
Published: January 2005

Central distribution of efferent and afferent components of the pudendal nerve was studied by the horseradish peroxidase (HRP) method in 13 macaque monkeys, i.e., in nine Japanese monkeys (Macaca fuscata), two rhesus monkeys (Macaca mulatta), and two crab‐eating monkeys (Macaca fascicularis). The enzyme was applied to the central cut end of the pudendal nerve; then the monkeys were allowed to survive for 36 to 72 hr.

Retrogradely labeled neuronal cell bodies of pudendal motoneurons constituted a slender longitudinal cell column in the ventral horn. The cell column extended from high or middle S1 to high or middle S2 in eight monkeys, from middle or low L7 to high S2 in four monkeys, and from high L7 to middle S1 in a monkey. The cell column appeared to correspond to Onuf's X nucleus in man. No sex difference was recognized in the position of the cell column.

The average number of HRP‐labeled pudendal motoneurons was larger in male than in female adult Japanese monkeys, whereas no sex difference was found in the average soma diameter of the pudendal motoneurons.

Transganglionically labeled axons entered into the spinal cord through the S1 and S2 dorsal roots in 12 monkeys and through the L7 and S1 dorsal roots in one monkey. Labeled axons were distributed ipsilaterally in laminae I–VI and X of the spinal cord at the same and adjacent levels of entry of HRP‐labeled dorsal root fibers (from L7 to S3 in 12 monkeys and from L6 to S3 in one monkey). At the levels of entry, some of the labeled dorsal root fibers crossed the midline of the cord through the dorsal commissural gray to distribute contralaterally in the medial portions of lamine I–VI, especially laminae III–V, of the dorsal horn. Although the craniocaudal extent of HRP‐labeled afferent fibers varied somewhat among 13 monkeys examined, no HRP‐labeled axons were observed in the gray matter of the spinal cord segments cranial to L6 and caudal to S3. In a Japanese monkey with a postoperative survival time of 72 hr, two clusters of labeled axons were observed ipsilaterally in the medial portions of the gracile nucleus.
The morphology and synaptic connections of spiny stellate neurons in monkey visual cortex (area 17): A golgi‐electron microscopic study
Authors: Marie Richard L. Saint , Peters Alan
Published: January 2005

Based on a gold‐toning, Golgi‐electron microscope examination of 12 small and medium‐sized spiny stellate neurons in laminae 4A, 4B, and 4C of the monkey visual cortex (area 17), the ultrastructure of the cell somata, dendrites, and axons of these neurons is described. Particular attention is paid to the synapses involving the surface of different parts of these neurons. Only symmetric synapses occur on the somata of spiny stellate neurons, and these occur with a frequency of 11.0–15.9 synapses/100 μm2 perikaryal surface. Symmetric synapses also occur on dendritic shafts and, occasionally, on dendritic spines. Asymmetric synapses are occasionally present along the dendritic shafts of spiny stellate neurons, but the majority of asymmetric synapses (75–95%) occur on their dendritic spines. The initial axon segments of the smallest spiny stellate neurons possess no axo‐axonal synapses, but several symmetric synapses are present along the initial segment of a medium‐sized, spiny stellate neuron in layer 4B. Fifty‐three synapses made by boutons of the axons of these spiny stellate neurons have been identified, and all are asymmetric. Sixty per cent of the synapses are formed by boutons en passant and the remainder by the terminal swellings of spine‐like axonal appendages, boutons terminaux. Of the synapses formed by the axons of spiny stellate cells, axo‐spinous synapses outnumber axo‐dendritic synapses two to one, and axo‐dendritic synapses involve both spinous and aspinous dendrites. Evidence is presented which suggests that many of the axon terminals forming asymmetric synapses with the dendritic shafts and spines of spiny stellate neurons are derived from other spiny stellate neurons.
Aspartate aminotransferase‐like immunoreactivity in the guinea pig and monkey retinas
Authors: Mosinger Judith L. , Altschuler Richard A.
Published: January 2005

The excitatory amino acids, aspartate and glutamate, have been proposed as retinal neurotransmitters. Aspartate aminotransferase (AAT) is an enzyme which is involved in the routine metabolism of these amino acids and may be involved in the specific synthesis of glutamate and/or aspartate for use as a neurotransmitter. On the basis of the hypothesis that increased levels of aspartate aminotransferase may reflect a transmitter role for aspartate and/or glutamate, we have localized aspartate aminotransferase in the guinea pig and cynamolgus monkey retinas with light and electron microscopic immunohistochemical techniques. AAT‐like immunoreactivity is localized to the cones of guinea pig retina and to monkey rods. Both species contain a subpopulation of immunoreactive amacrine cells as well as a subpopulation of immunoreactive cells in the ganglion cell layer. Immunostaining is seen in bipolar cells and terminals in the monkey but not in the guinea pig retina.

We have performed quantitative analysis of the immunoreactive staining in the outer plexiform layer and described the synaptic organization of immunoreactive processes in the inner plexiform layer (TPL). Labeled amacrine processes in both species form synaptic contacts predominantly to and from bipolar terminals in the inner third of the IPL and to and from other amacrine and small unidentified processes in the outer portion of the IPL. The majority of labeled bipolar terminals in the monkey retina are seen in the inner third of the IPL where they synapse exclusively onto amacrine processes. Labeled bipolar terminals in the outer third of the IPL occasionally synapse onto ganglion processes.
Rat medulla oblongata. III. Adrenergic (C1 and C2) neurons, nerve fibers and presumptive terminal processes
Authors: Kalia Madhu , Fuxe Kjell , Goldstein Menek
Published: January 2005

The 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).
Anatomy of the posterior lateral line system in young larvae of the zebrafish
Authors: Metcalfe Walter K. , Kimmel Charles B. , Schabtach Eric
Published: January 2005

We 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 development.
Growth and death of cells of the mesencephalic fifth nucleus in Xenopus laevis larvae
Authors: Kollros Jerry J. , Thiesse Mary L.
Published: January 2005

Positions, numbers, and cell and nuclear sizes of mesencephalic fifth nucleus (M‐V) cells were determined in Xenopus laevis larvae in stages 47 through the end of metamorphosis at stage 66. M‐V cells may be found at every tectal level, from the rostralmost section almost to the caudal pole, and in the anterior medullary velum. A large majority of the cells lie between 15 and 65% caudad of the rostral tip of the tectum. At anterior and middle tectal levels the cells lie lateral to but mainly above the optic ventricle. At posterior levels, to which the ventricle does not extend, a few cells may be seen at middle and lower tectal levels, as if in transition to the anterior medullary velum. At stage 47 fewer than ten cells are seen in each animal. The numbers rise to 20–40 by stage 50, and are uniformly above 100 after stage 51. Initially many M‐V cells were small, i.e., 6–7 μm in diameter, but grew to a mean diameter of about 19 μm at stage 59, with a maximum value of 29 μm. A single individual at stage 57 had 581 cells. The peak of mean cell numbers 387, occurred at stage 59, which was also the stage with the highest mean values for nuclear and cell sizes. Pyknotic M‐V cells at low frequency were seen at stages 55 and 57, and at all stages thereafter. Cell death frequency peaked at stage 62, but continued through stage 66. By stage 66 mean cell numbers had been reduced to about 240, indicating survival of about 60% of cells present at stage 59.
The neuronal composition of area 17 of rat visual cortex. I. The pyramidal cells
Authors: Peters Alan , Kara Daniel A.
Published: January 2005

The pyramidal cells in area 17 of rat visual cortex have been examined by light microscopy using Golgi preparations and semithin plastic sections, and by electron microscopy. Pyramidal cells have cell bodies in layers II–VIa. The pyramidal cells in the lower portion of layer II/III are typical examples of this neuronal type in that they have pyramidal‐shaped cell bodies, apical dendrites which ascend to layer I, and a skirt of basal dendrites. The pyramidal cells in upper layer II/III are similar in form but have shorter apical dendrites, while the most superficial pyramidal cells lack apical dendrites and instead have two or more primary dendrites that emanate from the upper surface of their somata. In layer V the pyramidal cells are of two sizes, medium and large, and both have a typical morphology, although the larger neurons have thicker apical dendrites and better‐developed axon hillocks than the medium‐sized pyramids. The medium‐sized pyramidal cells of layer V outnumber the large ones to a ratio of 2.5:1. In layer IV a few typical medium‐sized pyramidal cells are present, but the majority are small and can be regarded as star pyramids for they have dendrites radiating in all directions. No clearly identified spiny stellate cells have been encountered in layer IV. The pyramidal cells of layer VIa are also small, and most of them have apical dendrites which only ascend as far as layer IV. In addition to these varieties, both inverted and horizontally inclined pyramidal cells have been encountered.

In electron micrographs it is apparent that although all of the pyramidal cells have symmetric axosomatic synapses, the frequency with which these synapses occur varies. The cell bodies of the various forms of pyramidal cells do not show a standard cytology. The medium‐sized pyramidal cells of layer II/III usually have rounded nuclei, while the nuclei of the small pyramidal cells of layers IV and VIa are somewhat more irregular, and the large pyramidal cells of layer V have deeply indented nuclear envelopes. The appearance of the perikaryal cytoplasm also varies. The larger pyramidal cells have numerous mitochondria and well‐developed Nissl bodies in their perikaryal cytoplasm, but the smaller cells have much‐less‐pronounced mitochondria and their rough endoplasmic reticulum is only organized into stacks at the bases of dendrites.

Pyramidal cells account for about 87% of profiles of neuronal cell bodies with nuclei in layer II/III, 90% in layer IV, 89% in layer V, and 97% in layer VIa.
Degeneration of thalamic neurons in “Purkinje cell degeneration” mutant mice. II. Cytology of neuron loss
Authors: O'Gorman Stephen
Published: January 2005

The cytology of thalamocortical relay neuron degeneration in the ventral medial geniculate nucleus (vMG) of mice homozygous for the autosomal recessive Purkinje cell degeneration (pcd) mutation has been studied by light and electron microscopy. More limited sampling of the submedial and mediodorsal nuclei suggested that cytological alterations in the vMG were typical of all degenerating thalamic nuclei. The number of vMG neurons in pcd mutants was comparable to controls at and prior to postnatal day 40 (P40). By P60 seventy percent, and by P90 approximately 9%, of the original complement of vMG neurons had degenerated in mutant mice. At P30, the general cytological organization of vMG neurons closely resembled that of neurons in littermate (+/+ or +/pcd) controls, but neurons in mutants were distinguished by the presence of small aggregates of fine granules (approximately 9 nm in diameter) that were commonly associated with otherwise normal cisternae of rough endoplasmic reticulum; neither the number nor the size of these granular aggregates increased in older mutants. By P50 cytoplasmic organelles were curiously distributed in more severely affected neurons: large areas of cytoplasm were occupied exclusively by polysomes, while profiles of endoplasmic reticulum and the Golgi apparatus appeared to be reduced. Before frank degenerative changes were apparent (at P50), all classes of synaptic terminals identified in normal mice were found to have made morphologically normal synaptic contacts on mutant vMG neuron dendrites. In contrast to the homologous nuclear complex in the cat, presynaptic dendrites were not apparent in synaptic glomeruli in wild‐type or mutant murine vMG. Cytopathological alterations in the neuropil of P50 and older mutants were dominated by degenerating dendritic profiles; there was no evidence that the loss of thalamic neurons in pcd mutants was associated with synaptic agenesis or dysgenesis or the prior or concurrent degeneration of afferent synaptic terminals.
Telencephalic connections of the trigeminal system in the pigeon (Columba livia): A trigeminal sensorimotor circuit
Authors: Wild J. M. , Arends J. J. A. , Zeigler H. Philip
Published: January 2005

A combination of autoradiography and horseradish peroxidase histochemistry was used to identify telencephalic structures linking the sensory and motor components of the trigeminal system in the pigeon. A direct telencephalic projection from the principal trigeminal sensory nucleus upon the nucleus basalis via the quintofrontal tract was confirmed. Nucleus basalis projects upon a belt of neurons within the overlying neostriatum. This region (neostriatum frontale, pars trigeminale: NFT) gives rise to the fronto‐archistriate tract which terminates both in the archistriatum intermedium and in the overlying neostriatum caudale, medial to the ventricle (neostriatum caudale, pars trigeminale: NCT). NCT projects, in turn, upon a region of archistriatum intermedium containing cell bodies of the occipito‐mesencephalic tract. This pathway provides a link between the telencephalon and premotor areas within the lateral (parvicellular) reticular formation of the lower brainstem. The trigeminal sensorimotor circuit defined in these experiments has been implicated by neurobehavioral studies in the control of pecking, grasping, and feeding in the pigeon.
Depth segregation of retinal ganglion cells projecting to mouse superior colliculus
Authors: Hofbauer Alois , Dräger Ursula C.
Published: January 2005

The retinotectal projections in the mouse were analyzed with injections of horseradish peroxidase into the superior colliculus and of radioactive amino acids into the eye. At least 70% of the ganglion cells, and possibly all of them, were found to project to the superior colliculus, including ganglion cells of all sizes. Small injections revealed that ganglion cells of different sizes terminate at different levels in the superior colliculus. The small ganglion cells that form the vast majority of all cells project predominantly to the upper stratum griseum superficiale. A small population of mainly medium‐sized and large ganglion cells project to the deep stratum griseum superficiale and to the stratum opticum. The ipsilateral projection is restricted to the deep stratum griseum superficiale and stratum opticum and consists predominantly of medium‐sized and large ganglion cells.
Fine structure of peptidergic and catecholaminergic nerve fibers in the anterior cerebral artery and their interrelationship: An immunoelectron microscopic study
Authors: Matsuyama Tomohiro , Shiosaka Sadao , Wanaka Akio , Yoneda Shotaro , Kimura Kazufumi , Hayakawa Toru , Emson Piers C. , Tohyama Masaya
Published: January 2005

This study shows (1) the ultrastructure of vasoactive intestinal polypeptide (VIP)‐, substance P (SP)‐, and neuropeptide Y (NPY)‐containing nerve fibers in the walls of the cerebral arteries and (2) the relationship between these peptidergic (VIP, SP, and NPY) and catecholaminergic (CA) nerve terminals by immunohistochemistry combined with false transmitter (5‐hydroxydopamine) histochemistry under the electron microscope. VIP‐, SP‐, and NPY‐like immunoreactivity (VIPI, SPI, and NPYI) were found diffusely in the axoplasm and around the small clear vesicles in the nerve terminals. In a few cases, SPI was found within the large vesicles. Most of the VIPI terminals were ensheathed by the cytoplasm of the Schwann cells together with CA terminals, identified as those with a number of small granulated vesicles. In some cases, they were directly apposed to the smooth muscle cells at a distance of about 100 nm. SPI terminals were frequently solitary but about 30% were located together with CA and other (neither SPI nor CA) terminals ensheathed by Schwann cells, directly apposed to the smooth muscle cells at a distance of about 100 nm. On the other hand, NPYI terminals were also identified as CA terminals, indicating the coexistence of these two substances. These findings suggest a close interrelationship between peptidergic and CA nerve terminals in the neurogenic control of cerebral blood vessel function.
Efferent connections of the centromedian and parafascicular thalamic nuclei: An autoradiographic investigation in the cat
Authors: Royce G. James , Mourey Robert J.
Published: January 2005

The efferent projections of the centromedian and parafascicular (CM‐Pf) thalamic nuclear complex were analyzed by the autoradiographic method. Our findings show that the CM‐Pf complex projects in a topographic manner to specific regions of the rostral cortex. These fibers distribute primarily to cortical layers I and III; however, the projection to layer I is more extensive.

Following an injection into the rostral portion of the CM‐Pf complex, label is found within the lateral rostral cortex, particularly within the presylvian, anterior ectosylvian, and anterior lateral sulci, and within the rostral medial cortex where label is present within the cruciate and anterior splenial sulci and anterior cingulate gyrus. An injection into the caudal dorsal portion of the CM‐Pf complex results in label within the more ventral portions of the rostral lateral cortex where it is present within the anterior sylvian gyrus, presylvian regions, and gyrus proreus; and within the rostral medial cortex, where it is present within the rostral cingulate gyrus, and within the cruciate sulcus, and an extensive region ventral to the cruciate sulcus which includes the anterior limbic area. Injections into the caudal ventral portion of the CM‐Pf complex result in virtually no cortical label, although a few labeled fibers are found in the subcortical white matter.

The subcortical projection from the CM‐Pf complex terminates within the caudate nucleus, putamen, globus pallidus, subthalamic nucleus, zona incerta, fields of Forel, hypothalamus, thalamic reticular nucleus, and rostral intralaminar nuclei. Prominent silver grain aggregates are also present within the ventral lateral, ventral anterior, ventral medial, and lateral posterior nuclei, and ventrobasal complex. The aggregates in the thalamus appear to be fibers of passage, but whether these are also terminals cannot be determined with the techniques used in the present study.
Corticopontine projection in the macaque: The distribution of labelled cortical cells after large injections of horseradish peroxidase in the pontine nuclei
Authors: Glickstein Mitchell , May Jack G. , Mercier Barbara E.
Published: January 2005

We studied the distribution of corticopontine cells in the monkey cerebral cortex. Horseradish peroxoidase (HRP) was injected into the brainstem of monkeys in an attempt to fill the pontine nuclei on one or both sides. In control animals we injected the medullary pyramids or varied the route, size, or location of pontine injections. All retrograde filled corticopontine neurons were layer V pyramidal cells. Corticopontine cells were distributed within a largely continuous area of cortex which extended from the cingulate cortex medially to the sylvian fissure laterally; from the superior temporal fissure caudally to the medial part of the frontal granular cortex rostrally. Areas 4 and 6 of Brodmann (1905) contained the highest density of filled cells. In the primary visual cortex, area 17, there were a few labelled cells restricted to the rostral portion of the upper bank of the calcarine fissure, in a region representing the lower periphery of the visual field. The results are discussed in relation to the possible functions of the corticopontine system, especially the role of the extrastriate visual areas in visually guided movement.
Neuronal connections in the primary auditory cortex: An electrophysiological study in the cat
Authors: Mitani Akira , Shimokouchi Minoru
Published: January 2005

Neuronal connections in the primary auditory cortex (AI) of the cat were studied electrophysiologically by using intracellular recording techniques. Fast‐conducting fibers from the medial geniculate nucleus (MG) projected monosynaptically onto AI neurons in layers III–VI (mainly in layer IV), whereas slow‐conducting MG‐fibers projected monosynaptically onto AI neurons in layer I. AI neurons which received monosynaptic inputs from the auditory association cortices (AII and Ep) and/or from the contralateral AI were distributed in all layers of the AI; the commissural fibers from the contralateral AI were divided into fast‐ and slow‐conducting ones.

AI neurons were categorized into seven types: type I neurons which received monosynaptic inputs from slow‐conducting MG‐fibers were located in layer I. Type II neurons which received polysynaptic inputs from the MG were located in layers II–VI. Type III neurons which sent their axons to the AII or Ep were mainly located in layer III. Type IV neurons which sent their axons to the contralateral AI were located mainly in layer III. Type V neurons which received monosynaptic inputs from fast‐conducting MG‐fibers were located mainly in layer IV. Type VI neurons which projected onto the inferior colliculus were located in the upper part of the layer V. Type VII neurons which projected onto the MG were located in layers V and VI.
Light microscopic analysis of golgi‐impregnated rat subthalamic neurons
Authors: Afsharpour Salman
Published: January 2005

The neuronal morphology of the rat subthalamic nucleus (STH) was studied using Golgi techniques and Nissl stain. The results show that the somatic shapes of STH neurons vary from fusiform to oval or polygonal. Soamtic cross‐sectional areas vary between 140 μm2 and 440 μm2. Some of the cells have a few somatic spines. Two to six primary dendrites gave rise to tapering daughter dendrites which extend up to 500 μm. These dendrites are sparsely covered with spines. Some distal dendrites and primary dendrites of the STH also bear filiform appendages. Neurons located in the deep portion of the STH have oval dendritic fields whose long axis is parallel to the long axis of the nucleus in frontal or sagittal planes. Some of these neurons have one or two dendrites which cross the borders of the STH into the zona incerta, the lateral hypothalamus, or the cerebral peduncle. Generally, neurons located at the borders of the STH have their dendritic fields extending parallel to the borders and are confined to the nucleus. However, some neurons adjacent to the ventrolateral border of the nucleus have some dendrites extending into the cerebral peduncle. Quantitative analysis of the STH neurons showed a unimodal distribution of somatic sizes as well as the number of primary dendrites. No neurons with obvious Golgi type II characteristics were found.

Two types of afferent fibers were observed entering the STH. One type consists of axon collaterals arising from the cerebral peduncle ventrolaterally, or the internal capsule rostrally, while the other enters the nucleus after crossing the internal capsule rostrally.

These results suggest that the rat STH is an open nucleus in contrast to other species such as man, monkey, and cat, where it is closed, and that the rat STH may contain only one type of neuron.
Distribution of central cholinergic neurons in the baboon (papio papio). I. General morphology
Authors: Satoh K. , Fibiger H. C.
Published: January 2005

The morphological characteristics of cholinergic neurons in the central nervous system (CNS) of the baboon (Papio papio) were studied by choline acetyltransferase (ChAT) immunohistochemistry and acetylcholinesterase (AChE) pharmacohistochemistry. The distributions of central cholinergic neurons as visualized by these two histochemical techniques were similar in most, but not all regions of the brain and spinal cord. Based upon these observations, central cholinergic neurons that are immunoreactive to ChAT and intensely stained for AChE by the pharmacohistochemical procedure can be divided into four major groups: (1) those in the caudate nucleus, putamen, nucleus accumbens and anterior perforated substance. These ChAT‐containing and AChE‐intense neurons are large and multipolar, and are scattered throughout these structures. (2) The rostral cholinergic column, which consists of a continuous mass of cholinergic perikarya situated in the medial septal nucleus, nucleus of the diagonal band, and nucleus basalis (Meynert). The ChAT‐immunoreactive and AChE‐intense cell bodies of the nucleus basalis are a prominent feature in the basal forebrain of the baboon. The labeled neurons are large, multipolar, and hyperchromic and show a tendency to aggregate in cell clusters. These cells are distributed within the full extent of the substantia innominata, often being associated with sub‐cortical fiber networks such as the medullary laminae of the globus pallidus. (3) The caudal cholinergic column, which consists of a continuous group of cholinergic neurons in the caudal midbrain and pontine tegmentum. The rostral component of this group of cells is the nucleus tegmenti pedunculopontinus (subnucleus compacta) and it extends caudally to include the later‐odorsal tegmental nucleus. Compared to that in other species the nucleus tegmenti pedunculopontinus in the baboon appears to occupy a relatively greater volume and is composed of a greater number of cholinergic neurons. The cells of the caudal column are large and hyperchromic. (4) Nuclei of origin of somatic and visceral efferents of the cranial nerves (III, IV, V, VI, VII, IX, X, XI, XII) and spinal nerves. In addition to these major cholinergic cell groups, a small population of ChAT‐positive and AChE‐intense cell bodies can be observed at the floor of the fourth ventricle and in lamina VII and X of the cervical cord. The present findings indicate that although some differences exist, the overall distribution and morphological features of cholinergic cell bodies identified in the baboon brain and spinal cord are similar to those demonstrated previously in investigations of the rhesus monkey and nonprimates.
Organization of the nigrothalamocortical system in the rhesus monkey
Authors: Ilinsky I. A. , Jouandet M. L. , Goldman‐Rakic P. S.
Published: January 2005

The nigrothalamocortical connections and their topography were analyzed by autoradiography and double or triple retrograde labeling with the fluorescent dyes Fast Blue, Diamidino Yellow, and Propidium Iodide. Injections of tritiated leucine into different parts of the substantia nigra (SN) revealed that the medial SN projects to the medial magnocellular subdivisions of the ventral anterior (VAmc) and mediodorsal (MDmc) nuclei of the thalamus while the lateral SN projects to the more lateral and more posterior part of the VAmc, and the paralaminar, parvicellular, and densocellular subdivisions of the mediodorsal nucleus (MDmf, MDpc, and MDdc). With the exception of the MDmf, terminal areas observed in the mediodorsal nucleus were in the form of scattered clusters of grains. Analysis of the thalamus in cases with fluorescent dye injections into the lateral orbital gyrus (Walker's area 11), principal sulcus (area 46), anterior bank of the arcuate gyrus (areas 8 and 45), supplementary motor area (area 6), and motor cortex (area 4) revealed topographic organization of the nigrothalamocortical projection system. The parts of the VAmc and MDmc which receive afferents from the medial part of the SN in turn project to the most anterior regions of the frontal lobe including principal sulcus and orbital cortex. The lateral posterior VAmc, MDmf, MDpc, and MDdc, all of which receive afferents from the lateral part of the SN, project to more posterior regions of the frontal lobe including, in addition to the principal sulcus, the frontal eye field and also areas of the premotor cortex. These findings indicate that the SN has preferential targets in the thalamus and cerebral cortex which are segregated from those of the globus pallidus and cerebellum. Whereas the motor cortex is the primary target of cerebellar output (Asanuma et al., 1983b), and the premotor cortex is the target of pallidal output (Schell and Strick, 1984), the SN output appears to be directed more anteriorally—;to the prefrontal cortex.
Ontogeny of phenylethanolamine N‐methyltransferase‐ and tyrosine hydroxylase‐like immunoreactivity in presumptive adrenaline neurones of the foetal rat central nervous system
Authors: Foster G. A. , Schultzberg M. , Goldstein M. , Hökfelt T.
Published: January 2005

The appearance of phenylethanolamine N‐methyltransferase (PNMT)‐and tyrosine hydroxylase (TH)‐like immunoreactivity (LI) in the foetal rat central nervous system has been investigated. Antibodies raised against PNMT and TH were used in an indirect immunofluorescence method. Attention was focussed on areas containing putative adrenaline‐containing nerve cell bodies or fibres and, using an elution‐restaining technique, it was possible to analyze whether neurones contained PNMT‐LI, TH‐LI, or both. PNMT‐immunoreactive neurones could first be visualized on day 13 of gestation, in the ventrolateral and dorsal medulla oblongata, and probably corresponding to those of the C1 and C2 groups. The number of positive cell bodies and the intensity of their fluorescent staining in these areas were not dissimilar at this stage to the number and intensity observed at 1 day postnatal, the final age studied. At day 16, PNMT‐positive cells were observed for the first time in midline areas of the rostral dorsal medulla oblongata‐caudal pons, associated with the medial longitudinal fasciculus. These cells probably composed the C3 cell group. Many PNMT‐immunoreactive fibres could be seen at day 13 of gestation, in the medulla, and coursing both in an ascending bundle around the mesencephalic flexure and in a descending bundle toward the spinal cord. The extent of the bundles increased with gestational age, such that dense meshworks of PNMT‐immunoreactive varicose fibres were visible ventral to the aqueductus Sylvii, and the periventricular and lateral regions of the hypothalamus by days 18 to 19, and in the paraventricular nucleus, the septum, and the thoracic spinal cord by day 1 after birth. A sparser fibre plexus was observed in the amygdala at day 1 postnatal.

In contrast to the explosive appearance of PNMT‐immunoreactive cells at day 13 of gestation, the development of TH‐LI within these same neurones was much more protracted. Only rarely were TH‐LI awl PNMT‐LI colocalized at day 13, and even at birth TH‐LI could not be visualized in 5% of PNMT‐immunoreactive cells in the ventrolateral medulla oblongata, and in 50% of those in the dorsal vagal complex. A similar tardy appearance of TH‐LI in PNMT‐immunoreactive fibres was observed also. It should be emphasized that strongly TH‐immunoreactive neurones were found already at gestational day 10.5 in the medulla oblongata, caudal to the PNMT‐immunoreactive cells.

It is concluded that the expression of enzymes involved in the synthesis of adrenaline is not unitarily controlled, and may be partly dependent on other than epigenetic factors. Furthermore, ascription of the term adrenergic to a class of neurones appears to require the identification of more than a single synthetic enzyme.
An immunocytochemical study of the development of central serotoninergic neurons in the chick embryo
Authors: Wallace James A.
Published: January 2005

The development of central serotoninergic neurons in the chick embryo has been investigated immunocytochemically by utilizing an antiserum to serotonin (5‐HT). Immunoreactive neurons are first detected in the brain‐stem on embryonic day 4 (E4, stage 23), days earlier than 5‐HT systems have been detected previously by biochemical techniques. The earliest 5‐HT‐containing cells at E4 appear rostral to the pontine flexure, yet by E5, 5‐HT neuronal groups are observed throughout the brainstem from just caudal to the mesencephalic flexure to the cervical flexure. During this and subsequent phases of development, two distinct patterns of cellular migration seem to be involve‐l in the formation of the various 5‐HT neuronal groups. One pattern involves a ventral migration of 5‐HT cells, which appears dependent upon the directional guidance of midline radial processes (formed by floor plate cells) that extend across the neuroepithelium. The other pattern involves a lateral migration of cells, followed by an aggregation and rearrangement of 5‐HT neurons into distinct subgroups or clusters. Through these patterns of migration most components of the 5‐HT neuronal system can be recognized as early as E12, with the mature organization of the 5‐HT cell groups occurring by E17. One unexpected finding was the comparatively late appearance (between E9 and E12) of 5‐HT neurons in the paraventricular organ of the hypothalamus. Thus, in comparison to the initial observation of the majority of brainstem 5‐HT neurons at E4 to E5, the hypothalamic 5‐HT cells appear after a delay of between 5 and 7 days. Such differences illustrate the fact that neurons sharing a common neurotransmitter phenotype do not necessarily share the same developmental timetable for the expression of that particular phenotype, or they may undergo neurogenesis during considerably different periods of embryogenesis.
Spectral sensitivities of seven morphological types of photoreceptors in the retina of the turtle, Geoclemys reevesii
Authors: Ohtsuka Teruya
Published: January 2005

Spectral 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 the turtle retina.
Projections to the basilar pontine nuclei from face sensory and motor regions of the cerebral cortex in the rat
Authors: Mihailoff G. A. , Lee H. , Watt C. B. , Yates R.
Published: January 2005

Orthograde 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).
Ontogeny of tonotopic organization of brain stem auditory nuclei in the chicken: Implications for development of the place principle
Authors: Lippe William , Rubel Edwin W
Published: January 2005

The 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 fixed and immutable.
Cytology and intrinsic organization of the perihypoglossal nuclei in the cat
Authors: McCrea R. A. , Baker R.
Published: January 2005

The morphology of the neurons in the perihypoglossal nuclei (nucleus prepositus, nucleus intercalatus, and nucleus of Roller) of the cat was studied in normal Nissl material, and by intracellular injection of horseradish peroxidase.

The neurons in the nucleus prepositus were morphologically heterogeneous. Many of the cells in the ventromedial part of the caudal prepositus had relatively large somata, and complex dendritic trees which arose from numerous proximal dendrites and ramified extensively in the ventromedial aspect of the prepositus. These neurons had thick axons which typically did not give rise to local collaterals. The cells in the dorsolateral part of the caudal prepositus tended to have small somata, and dendritic trees which arborized in that region of the nucleus. The axons of these small cells frequently gave rise to local collaterals which terminated in the prepositus. Most of the cells in the prepositus had medium‐sized somata and relatively few dendrites which branched in an isodendritic manner and extended for long distances, frequently leaving the nucleus. These “principal” prepositus neurons had axons which arborized unilaterally, and often gave rise to collaterals which terminated in either the ipsilateral or contralateral prepositus. The neurons in the nucleus of Roller and nucleus intercalatus which were intracellularly injected with horseradish peroxidase resembled the multidendritic and small prepositus cells, respectively.

The intrinsic connectivity of the perihypoglossal nuclei was also studied by injecting horseradish peroxidase or 3H‐leucine into the prepositus nucleus. The results of these experiments suggest that the perihypoglossal nuclei are highly interconnected bilaterally, although the large cells in the ventromedial prepositus and the nucleus of Roller contribute little to these intrinsic connections, and are not major recipients of intrinsic inputs. On the other hand, the magnitude of the reciprocal connections between the prepositus and the nucleus intercalatus suggests that they are functionally related.
Cutaneous projections from the rat hindlimb foot to the substantia gelatinosa of the spinal cord studied by transganglionic transport of WGA‐HRP conjugate
Authors: Molander C. , Grant G.
Published: January 2005

The somatotopic organization of cutaneous afferent fibers from the hind‐limb foot in the substantia gelatinosa of the spinal cord was investigated in adult Sprague Dawley rats following intracutaneous injections of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP). The different parts of the foot were found to project in a precise manner to the medial two‐thirds of the substantia gelatinosa of the spinal cord segments L3–L5. The projections from the digits were arranged in a consecutive row rostrocaudally, with the most medial digit in caudal L3 and the most lateral digit in caudal L4 or rostral L5. The plantar skin was found to project both rostral and caudal to the projection of the digits. The dorsal foot skin projects lateral to the digits, neighboured by the medial edge of the foot rostrally and the lateral edge caudally. Within the projection of a particular digit, the plantar skin was found medially and the dorsal skin laterally. A certain degree of overlap for the projections from the different foot skin areas was found.