bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and differentiation of early generated cells of sublayer VIb in the somatosensory cortex of the rat: A correlated Golgi and autoradiographic study
Authors: Valverde Facundo , Facal‐valverde Maria Victoria , Santacana Maria , Heredia Margarita 
Published: January 2005

AbstractAutoradiographic and Golgi techniques are used to study the origin, developmental characteristics, and adult morphology of the cells of sublayer VIb in the somatosensory cortex of the rat. In the adult rat, this sublayer forms a stratum of two to three rows of cells located immediately above the white matter. It is clearly separated from the remaining cortical layers by a light plexus of fibers. The cortical plate begins to appear in the lateral wall of the brain hemisphere at embryonic day 15 (E15). By using tritiated thymidine autoradiography, we can see that cells generated between E12 and E14 become located in layers I, V, and VI in the adult. After injections on E12, heavily labeled cells were found almost exclusively in layer I and in sublayer VIb, indicating that these are the earliest generated cells in the neocortex of the rat. No labeled cells were found in sublayer VIb after injection on E15.We describe the morphology of cells of layer VI from E15 to the adult using the Golgi technique. Our observations show the existence of different types of cells, among which we found horizontal bipolar cells very early during development. They transform into horizontal and inverted pyramidal cells, which are the predominant morphological types found in the adult. Horizontal cells lie at the lower part of sublayer VIb. Inverted pyramidal cells have descending apical dendrites penetrating the white matter. Their axons form ascending loops turning into projection fibers. A correlation with previous studies and some functional implications indicating the unique role of sublayer VIb in the rat during development and in the adult are discussed.
Topographical organization of the efferent projections of the medial prefrontal cortex in the rat: An anterograde tract‐tracing study with Phaseolus vulgaris leucoagglutinin
Authors: Sesack Susan R. , Deutch Ariel Y. , Roth Robert H. , Bunney Benjamin S. 
Published: January 2005

AbstractThe purpose of the present investigation was to examine the topographical organization of efferent projections from the cytoarchitectonic divisions of the mPFC (the medial precentral, dorsal anterior cingulate and prelimbic cortices). We also sought to determine whether the efferents from different regions within the prelimbic division were organized topographically. Anterograde transport of Phaseolus vulgaris leucoagglutinin was used to examined the efferent projections from restricted injection sites within the mPFC.Major targets of the prelimbic area were found to include prefrontal, cingulate, and perirhinal cortical structures, the dorsomedial and ventral striatum, basal forebrain nuclei, basolateral amygdala, lateral hypothalamus, mediodorsal, midline and intralaminar thalamic nuclei, periaqueductal gray region, ventral midbrain tegmentum, laterodorsal tegmental nucleus, and raphe nuclei. Previously unreported projections of the prelimbic region were also observed, including efferents to the anterior olfactory nucleus, the piriform cortex, and the pedunculopontine tegmental‐cuneiform region. A topographical organization governed the efferent projections from the prelimbic area, such that the position of terminal fields within target structures was determined by the rostrocaudal, dorsoventral, and mediolateral placement of the injection sites.Efferent projections from the medial precentral and dorsal anterior cingulate divisions (dorsomedial PFC) were organized in a similar topographical fashion and produced a pattern of anterograde labeling different from that seen with prelimbic injection sites. Target structures innervated primarily by the dorsomedial PFC included certain neocortical fields (the motor, somatosensory, and visual cortices), the dorsolateral striatum, superior colliculus, deep mesencephalic nucleus, and the pontine and medullary reticular formation. Previously unreported projections to the paraoculomotor central gray area and the mesencephalic trigeminal nucleus were observed following dorsomedial PFC injections.These results indicate that the efferent projections of the mPFC are topographically organized within and across the cytoarchitectonic divisions of the medial wall cortex. The significance of topographically organized and restricted projections of the rat mPFC is discussed in light of behavioral and physiological studies indicating functional heterogeneity of this region.
Cell proliferation during early development of the chick embryo otic anlage: Quantitative comparison of migratory and nonmigratory regions of the otic epithelium
Authors: Alvarez Ignacio S. , Martín‐Partido Gervasio , Rodríguez‐Gallardo Lucía , González‐Ramos Carmen , Navascués Julio 
Published: January 2005

AbstractDuring development of the otic anlage, a certain proportion of epithelial cells migrate toward the mesenchymal compartment to form part of the acoustic‐vestibular ganglion. The migrating cells are observed only in the zone of the otic anlage that will make contact with the acoustic‐vestibular ganglion (so‐called ganglion zone). In Hamburger and Hamilton's stages 13 to 16, the number of epithelial cells that migrate is relatively low, but it becomes steadily higher from stage 17 on. In the otic anlage of chick embryos, between developmental stages 9 and 21 (48 to 94 hours of incubation), mitotic index, apical or basal localization within the epithelium of dividing cells, and orientation of the mitotic spindles were analyzed. These features in the ganglion zone were compared with observations in the rest of the otic epithelium, where migratory processes do not take place. In stages 13 to 15, when few epithelial cells are migrating, the mitotic index (MI) in the ganglion zone of the otic anlage is similar to that in nonmigratory regions. In more advanced stages, however, when cell migration becomes accelerated, the MI in the migratory zone of the otic wall is significantly higher than that in the rest of the otic epithelium. This suggests an intimate relationship between the migration of otic epithelial cells and a high rate of cell proliferation, the possible nature of which is discussed. Although the majority of mitoses in the otic anlage are located at the apical surface of the epithelium, from stage 13 onward, a few dividing cells are seen in the basal third of the epithelium. Furthermore, these basal mitoses appear exclusively in the migratory zone of the otic anlage, thus suggesting a possible relationship between epithelial cell migration and basal mitosis. During the developmental period prior to stage 18, no significant differences in mitotic spindle orientation are noted between migratory and nonmigratory zones of the otic anlage. In contrast, in stages of maximal otic epithelial cell migration (stages 19 to 21), the frequency of mitoses with the spindle axis oriented radially is significantly higher in the migratory zone. These findings point toward a close correlation between increased frequency of radial mitotic spindle orientation and intense cell migration, although the exact nature of this relationship is as yet unknown.
Morphology and distribution of neurons immunoreactive for substance P in the turtle retina
Authors: Cuenca Nicolas , Kolb Helga 
Published: January 2005

AbstractImmunocytochemical staining procedures with the HRP‐complexed antibody to substance P have been carried out on the turtle retina. Examination by light microscopy of wholemount retinas has allowed us to evaluate the morphology and distribution of the substance P immunoreactive cell types. Two amacrine cell types and two or more ganglion cell types are stained in our hands. Type A amacrines are tri‐stratified wide‐field amacrines. They have their major dendrites in S1 and S3 of the inner plexiform layer and they emit fine dendrites from the major dendrites that end in varicose boutons in S5 on and around cell bodies in the ganglion cell layer. Some of the dendrites in S1 radiate out in axon‐like fashion for 1 mm across the retina. The type B amacrine cells are small to medium‐field in dendritic extent. They have smaller cell bodies than type A and a single or, at most, two primary dendrites that pass directly to S3 before branching profusely into an intricate net‐like dendritic field. The ganglion cells that are stained with substance P antibodies appear to be of several types but their exact morphologies are in doubt because only portions of their major dendrites are stained. Substance P immunoreactive axons are clearly seen to project from the cell bodies to the optic nerve head and axons are stained in the optic nerve itself.The substance P‐stained ganglion cells occur in an irregular distribution that reaches a peak density in an elongated band parallel to and 1 mm below the visual streak. The type B amacrine cells reach a maximum density in the visual streak and are distributed in a highly regular mosaic decreasing in density in elliptical isodensity contours from the visual streak. In contrast the type A amacrine cells are rare or absent in the streak, being located in an irregular mosaic in peripheral retina.
On the number of purkinje cells in the human cerebellum: Unbiased estimates obtained by using the “fractionator”
Authors: Nairn J. G. , Bedi K. S. , Mayhew T. M. , Campbell L. F. 
Published: January 2005

AbstractStereological estimates of the numbers of Purkinje cell nucleoli in human cerebellar cortex have been obtained from systematic random samples of tissue by using the fractionator. The estimates are unbiased by fixation, section thickness, or sampling errors and are independent of any assumptions about cell shape, size, or spatial orientation. Twelve brains from aged subjects of both sexes were examined.The average complement of nucleoli in four female brains (age range 71–93 years) amounted to 14.8 millions (with an observed coefficient of variation between subjects of 29%). For three male brains (76–91 years), the corresponding estimates were 15.7 millions (10%). No significant sex differences were found for these small samples. Five brains of unknown sex and age yielded values of 15.8 millions (18%).For the twelve brains examined, the total number of Purkinje cell nucleoli per cerebellum was found to be 15.4 millions (19%). Estimated numbers showed a significant positive correlation with cerebellar weights. The number of nucleoli in an individual cerebellum was obtained with high precision in as short a time as 4 hours.
Development of calcitonin gene‐related peptide (CGRP) immunoreactivity in relationship to the formation of neuromuscular junctions in Xenopus myotomal muscle
Authors: Benjamin Peng H. , Chen Qiming , de Biasi Silvia , Zhu Dingliang 
Published: January 2005

AbstractImmunoreactivity (IR) to calcitonin gene‐related peptide (CGRP) has recently been found in chick motoneurons. Bath application of this peptide causes an increase in surface acetylcholine receptor (AChR) density and cAMP level in cultured chick muscle cells. These results suggest a role for this peptide in the formation of synaptic specializations. In this study, we examined the development of CGRP IR in larval Xenopus myotomal muscle in relation to synaptogenesis. Using an antiserum against CGRP, a monoclonal antibody against the p65 synaptic vesicle antigen and a fluorescence conjugate of α‐bungarotoxin, we followed the development of synaptic specializations with fluorescence microscopy in whole‐mount specimens. We found that the postsynaptic specialization in the form of AChR clusters was first detected in stage 22 (24 hour) embryos. The presynaptic specializations, including the synaptic vesicle clusters as evidenced by p65 antibody staining and CGRP IR, were first detected at stage 32 (40 hours). The appearance of these two presynaptic specializations followed the same time course. Subsequently, all three structures, the AChR clusters, CGRP IR, and synaptic vesicle clusters, were colocalized at the neuromuscular junction (NMJ). This shows that CGRP is unlikely to be involved in signaling the development of the postsynaptic apparatus. This premise is further examined in cultures of Xenopus myotomal muscle cells. CGRP at concentrations up to 1 μM did not affect the number of AChR clusters, nor did it interfere with the formation of clusters induced by polycation‐coated beads. In contrast, an extract from the basement membrane of Torpedo electric organ promoted the formation of AChR clusters and interfered with the clustering activity of the beads. These results suggest that CGRP, an integral component of the presynaptic specialization, is not involved in signaling synaptogenesis at the NMJ.
Corticotropin‐releasing factor immunoreactivity in monkey neocortex: An immunohistochemical analysis
Authors: Lewis David A. , Foote Stephen L. , Cha Choong I. 
Published: January 2005

AbstractCorticotropin‐releasing factor (CRF) has been implicated in the patho‐physiology of certain human neuropsychiatric disorders that affect neocortical function. However, the anatomical organization of CRF‐containing structures in the expanded and highly differentiated primate neocortex has not been previously described. In this study, the distribution of CRF‐immunoreactive neurons and processes was characterized in the neocortex of New World squirrel monkeys (Saimiri sciureus). Substantial regional differences were present in the density, laminar distribution, and morphological appearance of CRF‐immunoreactive neurons. The greatest density of labeled neurons was present in anterior cingulate cortex. A wide range of intermediate densities of CRF‐immunoreactive neurons was evident in the association regions of the prefrontal, parietal, and temporal cortices. The lowest numbers of CRF‐immunoreactive neurons were observed in the primary visual and primary motor cortices. For example, the density of labeled neurons was nearly five times greater in the anterior cingulate cortex than in the precentral cortex.CRF‐immunoreactive neurons were also distributed in at least four different laminar patterns. For example, in the agranular anterior cingulate cortex, labeled cell bodies were distributed throughout layers II, III, and V. In other regions, such as the posterior cingulate cortex, labeled neurons were present in layers II, III, and IV. In contrast, labeled neurons were predominantly present in layers II and superficial III of the visual cortex, whereas in the inferior temporal cortex, they were present predominantly in layer IV.Regional and laminar differences were also present in the relative distributions of the two major morphological types (as defined by cell body shape) of CRF‐immunoreactive neurons. Vertically oriented oval neurons, which frequently had a single dendritic process arising from each somal pole, were most frequently found in layer III. In contrast, the labeled neurons in layers II and IV tended to have a round‐ or triangular‐shaped soma. In layer IV of some association cortices, these multipolar neurons were associated with a high density of rod‐like structures composed of large immunoreactive varicosities clustered together in vertical arrays. These structures were frequently found to be located immediately below the soma of pyramidal neurons. Comparison of these findings with Golgi impregnation studies strongly suggests that CRF is present in the soma and axonal cartridges of a subset of chandelier neurons.The heterogeneous distribution and morphological diversity of CRF‐containing neurons suggest that CRF may mediate distinct functions in different regions and layers of monkey neocortex.
Embryonic development of four different subsets of cholinergic neurons in rat cervical spinal cord
Authors: Phelps Patricia E. , Barber Robert P. , Brennan Lynn A. , Maines Victor M. , Salvaterra Paul M. , Vaughn James E. 
Published: January 2005

AbstractThe developmental stage at which a neuron becomes committed to a neurotransmitter phenotype is an important time in its ontogenetic history. The present study examines when choline acetyltransferase (ChAT) is first detected within each of four different subsets of cholinergic neurons previously identified in the cervical enlargement of the spinal cord: namely, motor neurons, partition cells, central canal cluster cells, and dorsal horn neurons. By examining the temporal sequence of embryonic development of these cholinergic neurons, we can infer the relationships between ChAT expression and other important developmental events.ChAT was first detected reliably on embryonic day 13 (E13) by both biochemical and immunocytochemical methods, and it was localized predominantly within motor neurons. A second group of primitive‐appearing ChATpositive cell was detected adjacent to the ventricular zone on E14. These neurons seemed to disperse laterally into the intermediate zone by E15, and, on the basis of their location, were tentatively identified as partition cells. A third group of primitive ChAT‐immunoreactive cells was detected on E16, both within and around the ventral half of the ventricular zone. By E17, some members of this “U”‐shaped group appeared to have dispersed dorsally and laterally, probably giving rise to dorsal horn neurons as well as dorsal central canal cluster cells. Other members of this group remained near the ventral ventricular zone, most likely differentiating into ventral central canal cluster cells.Combined findings from the present study and a previous investigation of neurogenesis (Phelps et al.: J. Comp. Neurol. 273: 459–472, '88), suggest that premitotic precursor cells have not yet acquired the cholinergic phenotype because ChAT is not detectable until after the onset of neuronal generation for each of the respective subsets of cholinergic neurons. However, ChAT is expressed in primitive bipolar neurons located within or adjacent to the germinal epithelium. Transitional stages of embryonic development suggest that these primitive ChAT‐positive cells migrate to different locations within the intermediate zone to differentiate into the various subsets of mature cholinergic neurons. Therefore, it seems likely that spinal cholinergic neurons are committed to the cholinergic phenotype at pre‐ or early migratory stages of their development. Our results also hint that the subsets of cholinergic cells may follow different migration routes. For example, presumptive partition cells may use radial glial processes for guidance, whereas dorsal horn neurons may migrate along nerve fibers of the commissural pathway. Cell‐cell interactions along such diverse migratory pathways could play a role in determining the different morphological, and presumably functional, phenotypes expressed by spinal cholinergic neurons.
Distribution of hyaluronic acid and chondroitin sulfate proteoglycans in the presumptive aganglionic terminal bowel of ls/ls fetal Mice: An ultrastructural analysis
Authors: Tennyson Virginia M. , Payette Robert F. , Rothman Taube P. , Gershon Michaed D. 
Published: January 2005

AbstractThe terminal colon of the ls/ls mouse is aganglionic because an intrinsic defect prevents its colonization by cells migrating from the neural crest. Previous studies showed that laminin, type IV collagen, and glycosaminoglycans accumulate in the region of the presumptive aganglionic ls/ls bowel through which crest‐derived cells would be expected to migrate. It was suggested that crest‐derived cells might fail to enter the abnormal bowel because they receive inappropriate signals from a defective extracellular matrix. This hypothesis was evaluated by analyzing the ultrastructure of the extracellular matrix in mutant and control gut. Tissue was fixed in the presence of ruthenium red before or after selective enzymatic digestion. Heparan sulfate proteoglycan (diameter ≅ 15 nm) and chondroitin sulfate proteoglycan (diameter ≅ 20‐50 nm) granules were found in both control and presumptive aganglionic gut. The heparan sulfate proteoglycan granules were primarily located within formed basal laminae, while chondroitin sulfate proteoglycan granules decorated plasma membranes and 5 nm hyaluronic acid microfibrils that formed a network in the extracellular matrix. At day E11.5, the mutant gut differed from the control in the following: (1) Hyaluronic acid microfibrils were longer and more numerous. (2) There were larger numbers of chondroitin sulfate proteoglycan granules associated with cell membranes and with hyaluronic acid microfibrils. By day E13 the spaces between mesenchymal cells of the outer wall of the control bowel contained a regular lattice of hyaluronic acid microfibrils studded with chondroitin sulfate proteoglycan granules. Instead of this lattice, tangles of excessively long hyaluronic acid microfibrils, coated more heavily than in the control with chondroitin sulfate proteoglycan granules, were found in the presumptive aganglionic gut. These results confirm that the extracellular matrix is abnormal in the presumptive aganglionic bowel of the ls/ls mouse; moreover, they also indicate that the defect involves not one, but several components of the extracellular matrix, as well as their distribution. The defective extracellular matrix is apparent at a time when crest‐derived cells would be expected to be migrating in the terminal bowel and is located in their path. The observations thus support the idea that a localized abnormality of the extracellular matrix interferes with the colonization of the terminal bowel by crest‐derived cells in the ls/ls mouse.
Infrahyoid and accessory motoneurons in the japanese monkey (Mascaca fuscata)
Authors: Ueyama Teizo , Satoda Takahiro , Tashiro Takashi , Sugimoto Tetsuo , Matsushima Ryotaro , Mizuno Noboru 
Published: January 2005

AbstractThe segmental and topographical organization of motoneurons innervating the infrahyoid (IH) and the spinal accessory (AC) Muscles was studied in the Japanese monkey (Macaca fuscata) with thje retrograde horseradish peroxidase (HRP) method after application of HRP to the peripheral nerve branches supplying the IH and AC inuscles. IH motoneurons constitute two distinct slender cell columns, a longer medial and a shorter lateral one. The medial cell column extends from the most caudal level of the hypoglossal nucleus to the lower levels of the sececond cervical (C2) cord segment. In the medial column, motoneurons supplying the sternohyoid and sternothyroid muscles are distributed at the medullary and C1 levels, while those innervating the omohyoid muscle are primarily distributed at the C2 level. The lateral cell column consists of motoneurons supplying the thyrohyoid muscle and extends from the most caudal level of the hypoglossal nucleus to the middle levels of the C1 cord segment. Axons of thyrohyoid motoneurons follow a dorsomedially directed bent emergent course, making a hairpin turn.AC motoneurons supplying the sternocleidomastoid (SC) and trapezius (TZ) muscles form a single slender cell column extending from the most rostral level of the pyramidal decussation to the middle levels of the C6 cord segment. SC motoneurons are distributed from the most rostral level of the pyramidal decussation to the middle levels of the C3 cord segment, while TZ motoneurons are distributed from the upper levels of the C2 cord segment to the lower levels of the C6 cord segment. At the levels of the C2 and C3 cord segments, both SC and TZ motoneurons are distributed in the AC cell column; the cluster of SC motoneurons is located dorsomedial to that of TZ motoneurons.