bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synaptic complexes formed by functionally defined primary afferent units with fine myelinated fibers
Authors: Light A. R. , Perl E. R. , Réthelyi M. 
Published: January 2005

AbstractThe individual fine myelinated fibers of cutaneous mechanical nociceptors and “D‐hair” receptors were identified by electrophysiological recording with micropipette electrodes in cats and monkeys. Their intraspinal terminations were labeled by iontophoresing horseradish peroxidase intracellularly and subsequent diaminobenzidine histochemistry. These terminations were examined with light and electron microscopy to determine the nature and organization of their synaptic contacts.Myelinated fibers of the mechanical nociceptors became unmyelinated before exhibiting many enlargements that made multiple synaptic contacts in the marginal zone (lamina I) and lamina V. Pre‐or postsynaptic contacts were found only on enlargements. In the marginal zone of the cat, enlargements made simple axodendritic contacts or were scalloped, central terminals in glomeruli. In glomeruli, myelinated mechanical nociceptor enlargements were presynaptic to several dendritic appendages and postsynaptic to two different types of profiles. One type was interpreted as a presynaptic axon terminal, the other as a presynaptic, vesicle‐containing, dendritic appendage. In lamina V of the cat the nociceptor synaptic complexes were similar, but simpler, and only axonal profiles were found to be presynaptic to them. In the monkey marginal zone and deep nucleus proprius, myelinated nociceptor terminations formed the central element of glomeruli, which consisted of postsynaptic dendritic appendages and presynaptic axon terminals.D‐hair axons terminated in large numbers of enlargements in the nucleusproprius (laminae III and IV) and inner substantia gelatinosa (lamina III). Their large rounded enlargements formed the central terminals in glomeruli and were presynaptic to both ordinary and vesicle‐containing dendritic appendages; the presynaptic dendritic profiles also often contacted each other. Profiles interpreted as axonal in origin were the only terminals presynaptic to the primary ending within the D‐hair glomeruli.The results suggest that transfer of primary afferent information occurs only at enlargements of the primary fiber and that each primary fiber enters into more than one kind of synaptic arrangement. They also point out that synaptic glomeruli are common to functionally different types of primary afferent fibers and that the internal organization of glomeruli varies with the kind of primary fiber and the locus of the complex.
The effects of environmental diversity on well‐fed and previously undernourished rats: I. Body and brain measurements
Authors: Bhide P. G. , Bedi K. S. 
Published: January 2005

AbstractRats were undernourished from the 16th day of gestation to 25 postnatal days of age and then weaned on to an ad libitum diet. Around 35 days of age, 12 previously undernourished (PU) male pups were assigned to an “enriched environmental condition” (EC) and 12 to an “isolated environmental condition” (IC). Well‐fed controls were similarly assigned. After 30 days in these conditions all rats were killed by perfusion with fixative.Body and “forebrain” weights, and forebrain lengths and widths, were determined for each animal. The forebrains were subsequently embedded in paraffin wax and serially sectioned. Ten sections, identified by subcortical landmarks, were taken from each brain and used for cortical depth measurements. The whole experiment was carried out on two separate occasions.In both the well‐fed and PU groups the EC rats were between 3% and 9% lighter in body weight and between 4% and 9% heavier in “forebrain” weight than IC animals. A two‐way analysis of variance (two‐way ANOVA) indicated significant effects of nutrition and environment on body and forebrain weights but no significant interaction. Nutrition, but not environment, also had significant effects on “forebrain” width and length measurements.For the well‐fed groups, only one section out of all those measured from the two experimental series showed a significant effect of environment onthe cortical depth measurements.For the PU groups, in experiment one the cortical thickness of the EC rats was significantly greater than their IC counterparts in four out of theten sections analyzed. In the second experiment only two sections exhibitedsignificant results. In contrast to experiment one, these showed that the IC rats had a slightly but significantly thicker cortex than the EC rats. A two‐way ANOVA of the data on cortical depths showed no significant effects of, or interaction between, nutrition and environment.These observations are discussed in the context of previously publishedresults on the effects of a differential environment on body and brain measurements.
Fine structural localization of a new Purkinje cell‐specific glycoprotein subunit: Immunoelectron microscopical study
Authors: Langley O. K. , Reeber A. , Vincendon G. , Zanetta J. P. 
Published: January 2005

AbstractThe localization of a new low molecular weight glycoprotein subunit in cerebellum was studied with the aid of the indirect immunohistochemical method at the electron microscope level. The specificity of this molecule for Purkinje cells in the rat cerebellum suggested by earlier light microscope studies was confirmed. Immunoperoxidase reaction product indicative of the presence of this glycoprotein was exclusively limited to Purkinje cells, attached to the plasma membrane, membranes of the rough endoplasmic reticulum, the cytoplasmic surface of the nuclear membrane, and on polyribosomes. The antigen was found throughout the whole cell, except for the nucleus, and enabled Purkinje cell processes to be traced in the molecular layer, in the granule cell layer (including the nerve terminals in this layer), and to their axon terminals in the deep nuclei. The fine structural localization is discussed with reference to the known properties of this antigen.
Comparison of the morphology of physiologically identified abducens motor and internuclear neurons in the cat: A light microscopic study employing the intracellular injection of horseradish peroxidase
Authors: Highstein S. M. , Karabelas A. , Baker R. , McCrea R. A. 
Published: January 2005

AbstractAbducens motoneurons and internuclear neurons were identified electrophysiologically in anesthesized, paralyzed cats and stained by intracellular injection of horseradish peroxidase. Neurons were reconstructed and surface area of selected cells measured by light microscopy. Surface area of motoneurons and internuclear neurons with similar soma size and shape were roughly comparable. Dendrites of motoneurons were highly tapered and highly branched. By contrast, dendrites of internuclear neurons were less tapered and less branched. Axons of motoneurons had no collaterals within the brainstem. Internucler axons crossed the midline at the level of their parent somata and ascended in the medial longitudinal fasciculus toward the oculomotor nucleus. Approximately 30% of the internuclear axons branched in the contralateral medial longitudinal fasciculus sending a fine collateral caudal toward the prepositus hypoglossi nucleus. The results suggest that, on the average, structural correlates of injected neurons (i.e., soma‐dendritic morphology) can account at least in part for the earlier firing and higher intraburst frequencies of internuclear neurons versus motoneurons during on‐direction rapid eye movements in alert cats.
Anatomical banding of intrinsic connections in striate cortex of tree shrews (Tupaia glis)
Authors: Rockland K. S. , Lund J. S. , Humphrey A. L. 
Published: January 2005

AbstractThe intrinsic connectivity of striate cortex was investigated by injecting horseradish peroxidase (HRP) into this area in tree shrews. Such HRP injections demonstrated periodically organized, stripelike connections within area 17. These stripes occur in layers I–IIIA and consist of a small number of retrogradely filled neurons, some clearly pyramidal, together with HRP‐labeled axon terminals. HRP‐filled axon trunks run between labeled stripes, interconnecting adjacent and distant regions of the stripe pattern. Correlation with Golgi‐stained tissue suggests that these stripes are horizontally interconnected by pyramidal neurons with long intracortical axon collaterals (followed for distances over 1 mm form the soma). The HRP‐labeled stripes measure about 230 μm in width, with a center‐to‐center repeat distance of 450–500 μm. They have been mapped over an 8 mm2 area of striate cortex and would thus seem capable of effecting lateral interactions over considerable portions of the retinotopic map. In their dimensions and overall pattern, these anatomical stripes resemble the 2‐deoxyglucose (2‐DG) bands resulting from visual stimulation of tree shrews with stripes of a single orientation. While the functional role of the HRP‐labeled stripes is unclear, their similarities with the 2‐DG pattern raise the intriguing possibility that they may be related to orientation selectivity. The striking regularity of these extensive lateral interconnections emphasizes the importance of horizontal intralaminar connections within the cortex.
Two types of synaptic glomeruli and their distribution in laminae I–III of the rat spinal cord
Authors: Ribeiro‐Da‐Silva A. , Coimbra Antonio 
Published: January 2005

AbstractSystematic examination of photomontages revealed two types of synaptic glomeruli in laminae II‐III. Type I glomeruli have a dark small central (C) terminal of indented contour with closely packed spherical vesicles of variable diameter and few mitochondria. Among the peripheral terminals there are dendritic spines and a few presynaptic dendritic spines (V1 terminals) and axon endings rich in discoid vesicles (V2). These glomeruli occur in groups which are particularly evident in parasagittal sections in which successive C terminals are connected by narrower portions or dark unmyelinated profiles. Type II glomeruli have an electron‐lucent and large C terminal of regular contour with less packed synaptic vesicles of more uniform diameter, more mitochondria, and sometimes neurofilaments. Presynaptic dendrites are fewer and axon endings more numerous. C terminals in type II glomeruli are fusiform in longitudinal section, rarely occurring in groups.Lamina I is virtually devoid of glomeruli. Within lamina II, glomeruli are rare in a dorsalmost 20‐μm band and abundant in the immediately ventral 20‐μm band in which type I glomeruu are prevalent (ñ 79%). In ventral lamina II, type II glomeruli predominate (66%), being pratically exclusive in lamina III where most contain neurofilaments. Considering the distribution of terminations of primary afferents, it is suggested that type I C terminals originate from unmyelinated primary afferents, type II C terminals without neurofilaments from direct myelinated fibers, and those with neurofilaments from recurrent large fibers. The distinct numbers of presynaptic dendritic and axonal endings suggest different modulatory mechanisms functioning in the two types and in ventral vs. dorsal areas of this region.
Axonal guidance during development of the great cerebral commissures: Descriptive and experimental studies, in vivo, on the role of preformed glial pathways
Authors: Silver Jerry , Lorenz Suzanne E. , Wahlsten Douglas , Coughlin Jack 
Published: January 2005

AbstractDo structres exist within the embryonic central nervous system that guide axons across the midline during development of the great cerebral commissures (corpus callosum, anterior commissure)? With the use of serial section and reconstructive computer graphic techniques we have found that during normal ontogeny of the mouse forebrain and before the arrival of the pioneer fibers of the corpus callosum at the midline, a population of primitive glial cells migrates medially (through the fused walls of the dorsal septum) from the ependymal zones of each hemisphere. At the midline, and well rostral to the lamina terminalis, these cells unite to form a bridgelike structure of “sling” suspended below the longitudinal cerebral fissure. The first callosal axons grow along the surface of this cellular bridge as they travel toward the contralateral side of the brain. The “sling” disappears neonatally. The fibers of the anterior commissure grow within the lamina terminalis along a different type of preformed glial structure. Movement of these axons occurs through an aligned system of glial processes separated by wide extracellular spaces.Do these transient glial tissues actually provide guidance cues to the commissural axons? Analyses of three situations in which the glial “sling” is genetically or surgically impaired or nonexistent indicate that this structure does, indeed, play an essential role in the development of the corpus callosum. We have analyzed (1) the embryonic stages of a congenitally acallosal mouse mutant (strain BALB/cCF), (2) several pouch stages of a primitive acallosal marsupial, Didelphys virginiana (opossum), and (3) animals in which the “sling” had been lesioned surgically through the uterine wall in the normal embryo (strain C57BL/6J).In the acallosal mouse mutant fusion of the septal midline is delayed by about 72 hours and the “sling” does not form. Although the would‐be callosal axons approach the midline on schedule, they do not cross. Instead, the callosal fibers whirl into a pair of large neuromas adjacent to the longitudinal fissure. Similarly, in the opossum, fusion of the medial septal walls and formation of the glial “sling” are also lacking. However, in this species, instead of traveling dorsally, the “callosal” axons turn ventrally and pass contralaterally by way of the anterior commissure pathway. Surgical disunion of the glial “sling” also resulted in acallosal individuals. The callosal pathology in these affected animals mimicked exactly that of the genetically lesioned mutant. Our observations suggest that many different types of oriented glial tissues exist within the embryonic neural anlage. We propose that such tissues have the ability to influence the directionality of axonal movements and, thereby, play a crucial role in establishing orderly fiber projections within the developing central nervous system.
Segmental distribution and central projectionsof renal afferent fibers in the cat studied by transganglionic transport of horseradish peroxidase
Authors: Kuo David C. , Nadelhaft Irving , Hisamitsu Tadashi , de Groat William C. 
Published: January 2005

AbstractThe segmental and central distributions of renal nerve afferents in adult cats and kittens were studied by using retrograde and transganglionic transport of horseradish peroxidase (HRP). Transport of HRP from the central cut ends of the left renal nerves labeled afferent axons in the ipsilateral minor splanchnic nerves and sensory perikarya in the dorsal root ganglia from T12 to L4. The majority of labeled cells (85%) were located between L1 and L3. A few neurons in the contralateral dorsal root ganglia were also labeled. Labeled cells were not confined to any particular region within a dorsal root ganglion. Some examples of bifurcation of the peripheral and central processes within the ganglion were noted. A small number of preganglionic neurons, concentrated in the intermediolateral nucleus, were also identified in some experiments. In addition, many sympathetic postganglionic neurons were labeled in the renal nerve ganglia, the superior mesenteric ganglion, and the ipsilateral paravertebral ganglia from T12 to L3Transganglionic transport of HRP labeled renal afferent projections to the spinal cord of kittens from T1 1 to L6, with the greatest concentrations between Ll and L3. These afferents extended rostrocaudally in Lissauer's tract and sent collaterals into lamina I. In the transverse plane, a major lateral projection and a minor medial projection were observed along the outer and inner margins of the dorsal horn, respectively. From the lateral projection many fibers extended medially in laminae V and VI forming dorsal and ventral bundles around Clarke's nucleus. The dorsal bundle was joined by collaterals from the medial afferent projection and crossed to the contralateral side. The ventral bundle extended into lamina VII along the lateroventral border of Clarke's nucleus. Some afferents in the lateral projection could be followed ventrally into the dorsolateral portion of lamina VII in the vicinity of the intermediolateral nucleus. In the contralateral spinal cord, labeled afferent fibers were mainly seen in laminae V and VIThese results provide the first anatomical evidence for sites of central termination of renal afferent axons. Renal inputs to regions (laminae I, V, and VI) containing spinoreticular and spinothajamic tract neurons may be important in the mediation of supraspinal cardiovascular reflexes as well as in the transmission of activity from nociceptors in the kidney. In addition, the identification of a bilateral renal afferent projection in close proximity to the thoracolumbar autonomic nuclei is consistent with the demonstration in physiological experiments of a spinal pathway for the renorenal sympathetic reflexes.
Patterns of extraocular innervation by the oculomotor complex in the chick
Authors: Heaton Marieta B. , Wayne Demise B. 
Published: January 2005

AbstractThe horseradish peroxidase retrograde tracer technique was used to map tne projection pattern of the oculomotor nuclear complex to the extra‐ocular muscles in the chick embryo. The following projection pattern was found: The dorsolateral oculomotor subnucleus innervates the ipsilateral in‐ferior rectus muscle, the dorsomedial subnucleus innervates the ipsilateral medial rectus muscle, a lateral division of the ventromedial subnucleus innervates the ipsilateral inferior oblique muscle, and a medial division of the ventromedial subnucleus innervates the contralateral superior rectus muscle. The so‐called central nucleus also innervates the contralateral superior rectus muscle. This pattern was extremely discrete, with virtually no overlapping representations. These results provide the first evidence for a functional medial‐lateral subdivision of the ventromedial subnucleus. This pattern relates to the unusual development of this subnucleus and suggests that only part of the primordium for this cell group migrates across the mid‐line during its ontogeny, rather than all of it, as was previously believed. The subnuclear organization of the avian oculomotor complex is also considered in comparison to such functional organization in other species.
Visuotopic organization of projections from striate cortex to inferior and lateral pulvinar in rhesus monkey
Authors: Ungerleider Leslie G. , Galkin Thelma W. , Mishkin Mortimer 
Published: January 2005

AbstractAnatomical material from two series of monkeys (Macaca mulatta)was used to determine the full extent and visuotopic organization of striate projections to the pulvinar. One series was processed for degeneration by the Fink‐Heimer procedure following unilateral lesions of lateral, posterior, or medial striate cortex (representing the central, peripheral, and far peripheral visual field, respectively); collectively, the lesions included all of area 17. The second series was processed for autoradiography following tritiated amino‐acid injections into striate sites representing the center of gaze and eccentricities ranging from 0.5° to greater than 30° from fixation in both the upper and lower fields.The results indicate the existence of two separate striate projection zones within the pulvinar. One, the PI/PL zone, is located primarily within the inferiorpulvinar (PI) but extends into the adjacentlateral pulvinar (PL). The other, the PL zone, is located entirely within the lateral pulvinar and partially surrounds the first zone along its dorsal, lateral, and ventral aspects.Within the PI/PL zone, striate projections are topographically organized and represent the entire contralateral visual field. Central vision is represented laterally and posteriorly, with the fovea represented at the caudal pole of the nucleus; conversely, far peripheral vision is found medially and anteriorly, adjacent to the medial geniculate nucleus. The representation of the horizontal meridian runs obliquely across PI/PL, such that the upper visual field is located ventrolaterally and the lower visual field dorsomedially. The representation of the vertical meridian is located along the lateral margin of PI in anterior sections of the pulvinar, but within PL in posterior sections. Thus, the vertical meridian appears to form the border between the lateral margin of the PI/PL zone and the medial margin of the PL zone. At the lateral margin of the PL zone is the representation of its horizontal meridian. Striate projections to the PL zone, unlike those to the PI/PL zone, are limited to the representation of central vision. These results suggest that striate inputs contribute to the visual properties of neurons (Bender, 1981 a) throughout the PI/PL zone, but are insufficient to explain the visual properties of neurons outside of the central visual field representation in the PL zone.
Innervation of monkey extraocular muscles: Localization of sensory and motor neurons by retrograde transport of horseradish peroxidase
Authors: Porter John D. , Guthrie Barton L. , Sparks David L. 
Published: January 2005

AbstractNeurons that provide sensory and motor innervation of extraocular muscles in the monkey have been identified and localized by retrograde transport of horseradish peroxidase (HRP). Injections of HRP into individual extraocular muscles of rhesus or pig‐tail monkeys labeled pseudounipolar neurons that were localized within the ipsilateral semilunar ganglion. The distribution of labeled neurons within the ganglion was consistent with its somatotopic organization as the majority were found within the ophthalmic subdivision. Absence of labeled neurons within either the trigeminal mesencephalic or spinal nucleus was in agreement with previous findings in the cat (Porter and Spencer, '82). Intracranial transection of the ophthalmic nerve prior to muscle injection eliminated all labeling within the ganglion. These data indicate that the extraocular muscles can be selectively deafferented in order to examine the potential role(s) of proprioception in the neural control of eye movements.Injections of HRP into the extraocular muscles also resulted in the la beling of individual motoneuron populations. Each extraocular muscle was found to receive solely unilateral innervation, with contralateral representation of only the superior rectus and superior oblique. Within the oculomotor nucleus there was a moderate topographic segregation of individual motoneuron populations. Primate medial rectus and inferior rectus representations, while at variance with the classical descriptions (Warwick, '53), were consistent with those obtained in contemporary tracer studies (Büttner Ennever and Akert, '81; Spencer and Porter, '81). Superior rectus motoneurons were distributed along the medial aspect of the contralateral nucleus, with the predominant representation at caudal to midnuclear levels. Inferior oblique motoneurons filled the gap lateral to those of the superior rectus and ventral to medial rectus (dorsal subgroup) and inferior rectus representations at their respective levels. Following injections of the lateral rectus and superior oblique labeled motoneurons were found within the ipsilateral abducens nucleus and contralateral trochlear nucleus, respectively. Superior oblique motoneurons were strictly confined to the well‐defined neuronal borders of the trochlear nucleus. Those innervating the lateral rectus, in addition to lying within the abducens proper, extended ventrolaterally from the nucleus to form a discrete ventral abducens nucleus. Our data provide a complete description of the innervation pattern of primate extraocular muscles which is based upon contemporary tracer techniques. These findings include the first demonstration of the localization of monkey first‐order afferent neurons which subserve extraocular muscle proprioception.