bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autoradiographic localization of progestin‐concentrating cells in the brain of the zebra finch
Authors: Lubischer Jane L. , Arnold Arthur P. 
Published: January 2005

AbstractThe production of song in passerine birds is under the control of steroid hormones, and brain regions involved in song production have been shown to contain androgen and/or estrogen receptors. Studies to date, however, have not considered the possible role of progestins in this behavior. As one approach to this question, the autoradiographic method was used to investigate the distribution of progestin‐concentrating cells in the brain of the adult male zebra finch (Poephila guttata) after injection of the radiolabeled synthetic progestin [17α‐methyl‐3H]‐promegestone. In the telencephalon, identifiable groups of progestin‐accumulating cells were found in the hyperstriatum dorsale, at the medial edge of the lobus parolfactorius, and in the medial septum. In the diencephalon, labeled groups of cells were found in the preoptic area, through much of the medial hypothalamus‐‐including nucleus periventricularis magnocellularis, nucleus medialis hypothalami posterialis, and area infundibularis‐‐and in the medial spiriform nucleus and dorsomedial thalamus. In the myelencephalon, labeled cells are described at the dorsal edge of the medulla and scattered lateral to nXII. These findings offer no support for the hypothesis that progestin acts on any of the known song regions, but do suggest areas of progestin action in the avian central nervous system outside of the known song system. Not surprisingly, these include many areas of the medial hypothalamus and other midline structures.
Projections ascending from the spinal cord to the brain in petromyzontid and myxinoid agnathans
Authors: Ronan Mark , Northcutt R. Glenn 
Published: January 2005

AbstractThe course of projections ascending through the rostral spinal cord to nuclei in the brains of petromyzontid and myxinoid agnathans was examined with silver staining of anterograde degeneration and horseradish peroxidase histochemistry. As in jawed vertebrates, the ascending spinal projections of lampreys and hagfishes appear to be organized into two major systems, the spinal lemniscal and dorsal column pathways. The spinal lemniscal pathway, extending rostrally along the ventrolateral margin of the spinal and medullary central gray, consists of a spinoreticular and possibly a spinovestibular projection in both aganthan groups. In Pacific hagfish, spinal lemniscal fibers reach the ipsilateral mesencephalic tectum, but no spinal projection to the thalamus was evident. The spinal lemniscus of lampreys ascends to the region of the isthmus and may extend into the mesencephalic tegmentum. Anterograde and retrograde tracing methods indicate that a very small population of cells in the far rostral cord of lampreys may project to the optic tectum and diencephalon; however, spinotectal and spinothalamic projections, if present, are limited in extent. The dorsal column pathway in agnathans, consisting in part of primary spinal afferents, ascends in the dorsal funiculus of the cord. The dorsal column fibers of agnathans, like those of some other anamniotes, continue beyond the spinomedullary junction through the length of the hindbrain, possibly conveying ascending somatosensory input to the sensory nuclei of the alar medulla.
Neurons of the lateral entorhinal cortex of the rhesus monkey: A golgi, histochemical, and immunocytochemical characterization
Authors: Carboni A. A. , Lavelle W. G. , Barnes C. L. , Cipolloni P. B. 
Published: January 2005

AbstractThis study identifies the neuronal types of the rhesus monkey lateral entorhinal cortex (LEC) and discusses the importance of these data in the context of the connectional patterns of the LEC and the possible role of these cells in neurodegenerative diseases. These neuronal types were characterized with the aid of Golgi impregnation techniques. These characterizations were based upon their spine densities, dendritic arrays, and, where possible, axonal arborizations. The cells could be segregated into only spinous and sparsely spinous types. The most numerous spinous types were pyramidal neurons. Other spinous types included multipolar, vertical bipolar and bitufted, and vertical tripolar neurons. The sparsely spinous neuronal types consisted of multipolar, horizontal bipolar and bitufted, and neurogliaform cells.These cells were further classified with the aid of histochemical stains and immunocytochemical markers. Nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐d) histochemistry stained multipolar, bipolar, and bitufted neurons. Stain for cytochrome oxidase (CO) was found in pyramidal and nonpyramidal cell types. Immunocytochemical techniques revealed several nonpyramidal neurons that contain somatostatin (Som) or substance P (SP). This study complements previous analyses of the neuronal components described in the LEC and adds further information about the distribution of selected neurochemicals within this cortex.
Estradiol‐concentrating forebrain and midbrain neurons project directly to the medulla
Authors: Corodimas Keith P. , Morrell Joan I. 
Published: January 2005

AbstractThe location and number of estradiol (E2)‐concentrating neurons afferent to the dorsal medulla were determined by combining retrograde fluorescent tract tracing with steroid hormone autoradiography. Injections of Fluoro‐Gold were made into the medulla of 80 day old, ovariectomized, and adrenalectomized female rats. After 7 days survival to allow for retrograde transport, females were injected with [3 H] estradiol; they were then perfused and their brains processed for steroid hormone autoradiography. Following a 4hyphen;12 month exposure period, autoradiograms were developed and microscopically analyzed for the presence of E2‐concentrating neurons that project to the medulla.Numerous E2‐concentrating neurons were identified that send axons directly to the medulla; the majority were found in the bed nucleus of the stria terminalis, paraventricular nucleus of the hypothalamus, central nucleus of the amygdala, and the central gray. Of the E2‐concentrating neurons in the bed nucleus of the stria terminalis, 12.7% also projected to the medulla. E2‐concentrating neurons that sent axons to the medulla were also identified in and ventromedial to the lateral parvicellular subdivision in the caudal half of the paraventricular nucleus of the hypothalamus (69.4%). Over one‐third of the E2‐concentrating neurons found in the central nucleus of the amygdala coursed to the medulla. The central gray was the only mesencephalic brain region that contained E2‐concentrating neurons that projected to the medulla (41.9%).The medulla‐bound E2‐concentrating forebrain and midbrain neurons identified in the present study may influence autonomic tone via direct projections.
Musculotopic organization of the facial motor nucleus in macaca fascicularis: A morphometric and retrograde tracing study with cholera toxin B‐HRP
Authors: Welt Carol , Abbs James H. 
Published: January 2005

AbstractMorphometric and retrograde tracing methods were used to determine the location and number of motoneurons innervating individual facial muscles in Macaca fascicularis. Intramuscular injections of the cholera toxin B subunit‐horseradish peroxidase conjugate produced discrete labeling patterns in the ipsilateral facial motor nucleus with good definition of somata and their processes. The facial nucleus extended rostrocaudally in the pons for about 2 mm, varying in shape and cross‐sectional area along this axis. Motoneurons were clustered in subnuclei, but their boundaries were not sharp and they were not segregated by fiber bundles. The length, number, and area of subnuclei varied with rostrocaudal location.Retrograde labeling patterns revealed that individual muscles were innervated by longitudinal columns of motoneurons with each muscle region represented at all rostrocaudal levels of its column. The columns began at different rostrocaudal levels and varied in length. Columns for closely related muscles, such as the orbicularis oris and mentalis of the lower lip, tended to overlap, whereas columns for disparate muscles, such as the perioral and orbital, did not overlap. The dendritic processes of most motoneurons branched extensively among several different columns or subnuclei. Some dendrites extended outside of the nucleus into the surrounding tegmentum.Mean soma diameter (10.4‐42.2 μm) was distributed unimodally, reflecting the absence of gamma motoneurons and lack of muscle spindles in the facial muscles. Large and small motoneurons were found in all regions of the nucleus, but the largest ones were located caudally and innervated muscles of the upper and lower lip. The perioral muscles also had more neurons, longer columns, and a lower cell density than the other muscle groups examined. These features may reflect the functions of the perioral muscles in facial expression and vocalization.
Neurogenesis of the magnocellular basal forebrain nuclei in the rhesus monkey
Authors: Kordower Jeffrey H. , Rakic Pasko 
Published: January 2005

AbstractThe time of origin of the neurons that comprise the magnocellular basal forebrain nuclei in rhesus monkeys was determined by using [3H] thymidine autoradiography. Thirteen pregnant animals received an injection of [3H] thymidine between embryonic days 27 (E27) and E50 of their 165 day gestation, and their offspring were sacrificed during the early postnatal period. Neurons within this region were generated in a biphasic pattern. An initial burst of [3H] thymidine‐labeled magnocellular neurons was first observed throughout short quiescent period, cells of the remaining anterior basal forebrain (inclusive of magnocellular neurons comprising the vertical limb of the diagonal band and the anteromedial and anterolateral regions of the nucleus basalis) were generated between E36 and E45 with a peak of neurogenesis seen on about the same time, but the peak period of neurogenesis in this region occurred slightly earlier (E36 and E40) and was completed by E43. During the second phase of neurogenesis, neurons within the posterior division of the basal forebrain were generated first, with their genesis virtually completed between E33 and E36. The genesis of all neurons comprising the magnocellular basal forebrain nuclei was completed by E48 of gestation. A general caudal to rostral gradient of neurogenesis was observed within this telencephalic region. In contrast, a neurogenic gradient was not discerned in the radial direction. The present data demonstrate that neurons comprising the basal forebrain magnocellular nuclei in monkeys are generated early in gestation with two peak times of neuronal genesis. These nuclei are among the earliest to be generated in the entire telencephalon, which, like neurons of the thalamus and cortical neurons giving rise to cortical‐cortical connections, places them in a strategic position to potentially influence their target neurons within the cortical mantle that are generated later in gestation.
Timing and patterns of astrocyte migration from xenogeneic transplants of the cortex and corpus callosum
Authors: Zhou Hai Feng , Lee Lawrence Hou‐Chung , Lund Raymond D. 
Published: January 2005

AbstractThe timing, pattern, and pathway of astrocyte migration were investigated in vivo by transplantation of CD‐1 mouse cerebral cortex E13‐14 or corpus callosum P2‐3 into neonatal rat cortex. A monoclonal antibody specific for a mouse astrocyte surface antigen M2 was used to identify the location of the grafts and the migrated donor astrocytes. Within the host cortex, astrocytes from cortical grafts began migration at post‐transplantation day PTD 7. Over the next 4 days, the most distant displaced donor cells were found progressively further away from the grafts, migrating at a rate of about 220 μm/day. After PTD 11, the migration rate for the farthest displaced donor cells slowed to 25 μm/day, and the cells appeared to stop at about PTD 16 at a distance of 1,100 μm from the edge of the graft. Astrocytes had a faster migration speed in the white matter and covered a longer distance (5 mm) than those in the gray matter, extending on occasion into the contralateral hemisphere. The patterns of astrocyte migration differed depending on local cues around the transplant. Donor astrocytes that had been implanted into the host cortex migrated toward the host cortical surface, sometimes ín several radial lines. Astrocytes from grafts, especially callosal grafts, placed in the subcortical white matter migrated along the host fiber tracts. Many astrocytes transplanted into the hippocampus formed laminar patterns close to the hippocampal neuronal layers. These results suggest that the direction, pattern, and speed of astrocyte migration are influenced by local substrates in the host brain.
Transient patterns of GAP‐43 expression during the formation of barrels in the rat somatosensory cortex
Authors: Erzurumlu Reha S. , Jhaveri Sonal , Benowitz Larry I. 
Published: January 2005

AbstractThe development of the rat barrel field cortex was investigated with an antibody to the axonal membrane‐specific phosphoprotein GAP‐43 in order to examine the developmental pattern of afferent projections, and with cytochrome oxidase histochemistry and Nissl stains to reveal the morphogenesis of cortical barrels.On the first two days after birth, GAP‐43 immunostaining in the cortical plate was light and diffuse, then became intense in the presumptive layer IV of the parietal cortex on PND3 (day of birth = PND0). Immunoreactive densities were visible as small, focal patches within the centers of prospective barrels. These densities increased in size and intensity over the next few days and then diminished abruptly. On PnD7, the distribution of GAP‐43 was coextensive with barrels, as defined by cytochrome oxidase histochemistry and Nissl staining. GAP‐43 virtually disappeared from the barrels after PND7. From the second postnatal week, GAP‐43 immunostaining was evident in the septa between barrels and in the dysgranular regions of SI cortex. This pattern of GAP‐43 distribution was complementary to the pattern of cytochrome oxidase activity, and persisted into maturity.In an attempt to identify possible source(s) of GAP‐43 positive afferents in the developing barrels, we examined the effects of altering the sensory periphery on the distribution of GAP‐43 immunostaining in the cortex. Rat pups had row C whiskers cauterized on PND0 and were sacrificed on PND3 or PND5. Whereas immunopositive densities corresponding to intact whiskers developed in a normal, punctate pattern, cortical representation of the lesioned whiskers formed a continuous band of labeling that was evident as early as PND3.We argue that the disjunctive expression of GAP‐43 in the barrel field reflects the pattern of distribution of afferents (most likely from the ventrobasal thalamic nucleus) to the barrel field cortex, and that this pattern may be instructive in the formation of barrels as cytoarchitectonic units. The rapid alteration in patterns of immunostaining following whisker lesions lends further support to the conclusion that the “barrel template” is conveyed to the neocortex by incoming afferents. The possible significance of the transient expression of GAP‐43 in the maturing barrel field is discussed.
Human photoreceptor topography
Authors: Curcio Christine A. , Sloan Kenneth R. , Kalina Robert E. , Hendrickson Anita E. 
Published: January 2005

AbstractWe have measured the spatial density of cones and rods in eight wholemounted human retinas, obtained from seven individuals between 27 and 44 years of age, and constructed maps of photoreceptor density and between‐individual variability. The average human retina contains 4.6 million cones (4.08–5.29 million). Peak foveal cone density averages 199,000 cones/mm2 and is highly variable between individuals (100,000–324,000 cones/mm2). The point of highest density may be found in an area as large as 0.032 deg2. Cone density falls steeply with increasing eccentricity and is an order of magnitude lower 1 mm away from the foveal center. Superimposed on this gradient is a streak of high cone density along the horizontal meridian. At equivalent eccentricities, cone density is 40–45% higher in nasal compared to temporal retina and slightly higher in midperipheral inferior compared to superior retina. Cone density also increases slightly in far nasal retina. The average human retina contains 92 million rods (77.9–107.3 million). In the fovea, the average horizontal diameter of the rod‐free zone is 0.350 mm (1.25°). Foveal rod density increases most rapidly superiorly and least rapidly nasally. The highest rod densities are located along an elliptical ring at the eccentricity of the optic disk and extending into nasal retina with the point of highest density typically in superior retina (5/6 eyes). Rod densities decrease by 15–25% where the ring crosses the horizontal meridian. Rod density declines slowly from the rod ring to the far periphery and is highest in nasal and superior retina. Individual variability in photoreceptor density differs with retinal region and is similar for both cones and rods. Variability is highest near the fovea, reaches a minimum in the midperiphery, and then increases with eccentricity to the ora serrata. The total number of foveal cones is similar for eyes with widely varying peak cone density, consistent with the idea that the variability reflects differences in the lateral migration of photoreceptors during development. Two fellow eyes had cone and rod numbers within 8% and similar but not identical photoreceptor topography.
Branching patterns of corticospinal axon arbors in the rodent
Authors: Kuang Rong Zhen , Kalil Katherine 
Published: January 2005

AbstractDespite extensive study of corticospinal connections in a variety of species, little is known about the detailed morphology of corticospinal axon arbors. Results in previous studies of primates based on intra‐axonal filling with horseradish peroxidase (HRP) staining of a limited sample of fibers suggest that corticospinal arbors branch widely to multiple motoneuronal pools. To determine whether this pattern of corticospinal connectivity is present in nonprimate species as well, we studied the branching patterns of corticospinal axon arbors in a rodent species, the golden hamster. The axons were labeled by iontophoretic ijection of Phaseolus vulgaris‐leucoagglutinin (PHA‐L) into small regions of the forelimb and hindlimb sensorimotor cortex, and immunohistochemistry with the peroxidase‐antiperoxidase (PAP) method was used to reveal fine details of terminal arbors within the cervical and lumbar enlargements of the spinal cord. As in higher mammals, corticospinal connections are topographically organized. Moreover, corticospinal axons arising from somatosensory cortx project primarily to the dorsal horn, whereas those from motor cortex terminate most heavily in the ventral horn. This differential projection pattern, not previously demonstrated in rodents, implies functional differences between somatosensory and motor components of the corticospinal pathway. Reconstruction of corticospinal arbors in the ventral horn showed that in both cervical and lumbar spinal cord segments, axons branch widely into interneuronal regions. A surprising number appear to extend into motoneuron cell groups, and some of these axons branch into multiple motoneuronal pools. Widely divergent corticospinal axons that branch to multiple motoneuron pools have been shown to mediate activity in functionally related muscle groups of the primate forearm. The present results suggest that in other species, such as the rodent, a similar divergence of corticospinal arbors may also function to facilitate activity in subsets of muscles.
Shapes and distributions of the catecholamine‐accumulating neurons in the rabbit retina
Authors: Tauchi Masaki , Madigan Nancy K. , Masland Richard H. 
Published: January 2005

AbstractRabbit retinas were fixed with mixed aldehydes and examined for the fluorescence of catecholamines. Labeled cell bodies were present in the layer of the amacrine cells. A band of fluorescent processes was present in layer 1 of the inner plexiform layer. Weaker labeling was present in two deeper strata, one near the middle of the inner plexiform layer (presumably layer 3) and one at the juction of layers 4 and 5. Immunohistochemistry showed tyrosine hydroxylase (TH) to be present in the same cells and the same strata of the inner plexiform layer as the endogenous catecholamines. Exposing the retina to exogenous dopamine or norepinephrine resulted in stronger labeling in the middle and deep levels of the inner plexiform layer. At the same time a second population of amacrine cell bodies became visible.Catecholamine fluorescence contained in the amacrine cell bodies was used as a guide to their injection with Lucifer yellow CH. The filled dendritic arbors revealed two main types of cells. The type 1 cells are monostratified at the most distal level of the inner plexiform layer. They have relatively uncomplicated, radially branching dendritic trees. They are the cells densely stained by immunohistochemistry with antibodies against. TH. The type 2 cells are tristratified, with minor branching in layer 1 of the inner plexiform layer and major branching in the two deeper sublayers. The descending dendrites follow a complicated course, and it is not uncommon for intermediate dendrites to cross between strata more than once.The relationship of the cells to their dendritic plexuses was further studied in retinas in which the aldehyde‐induced fluorescence of catecholamines was photoconverted to a diaminobenzidine product. The type 1 cells were found to dominate the plexus of dendrites in layer 1 of the inner plexiform layer. The catecholaminergic plexuses in the middle and deep levels of the inner plexiform layer are formedf by dendrites of the type 2 cells.The position of every type 1 cell was mapped in retinas stained with antibodies directed against TH. In one retina we counted 5,613 type 1 cells, distributed evenly across the retina. In another retina, all of the catecholamine‐accumulating cells were counted. There were 9,058 with a distribution that peaks in the visual streak. The type 1 cells appear to be the dopaminergic cells previously studied by others and thought to regulate the flow of information from rod bipolar cells to ganglion cells. The low density and wide spread of type 2 cells suggests that they, too, perform a generalized control function, presumably a novel one that dictates their intricate, tristratified shape.