bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the epithalamus. I. Morphology of post‐mortem degeneration: The habenular nucleus in dog
Authors: Haines Duane E. , Jenkins Thomas W. 
Published: January 2005

AbstractThis study was undertaken to observe the structural changes occurring in myelin, axis cylinders, Nissl substance, nucleus, and general cell architecture at specific post‐mortem time intervals.The habenulopedunclar tract and the habenular nucleus of 36 adult dogs were sectioned (6 μ to 14 μ) and stained with luxol fast blue‐cresyl echt violet, 2% osmium tetroxide, and a two hour Protargol method. At O hour post‐mortem the cell membrane is relatively distinct, nuclear membrane delicate but distinct, nucleolus clear, Nissl bodies are observed in larger cells of the habenular nuclei.From 6–24 hours three main areas of change are noted: an agglutination, fragmentation, and obliteration of the Nissl substance; a progressive increase in the irregularity of the nuclear and cell membrane; a progressive increase in vaculation and in the perinuclear halo. From 24–36 hours the cytoplasm appears extremely granular with the granulation extending into the nucleus. Some cells appear swollen with indistinct nuclei or appear anucleated. From 36–48 hours the cytoplasm shows increased granulation and at 48 hours few cells show nuclei. Most cells show uniform color in the cytoplasm and nuclear area. Any remaining nuclei in the 36–48 hour interval appear pyknotic and finely granular. The myelin sheaths and axis cylinders show only limited structural change over the time span of this study.
Central projections of brachial and lumbar dorsal roots in reptiles
Authors: Joseph Barry S. , Whitlock David G. 
Published: January 2005

AbstractThe central distributions of single lumbar and brachial dorsal roots have been determined in the reptiles: Caiman sclerops, Ctenosaura hemophila and Iguana iguana. Degeneration resulting from root transections was assessed by means of the uranyl nitrate modification of the Nauta method. All dorsal root projections were entirely ipsilateral to the side of the damaged roots. A projection to the ventral horn was found in the lizards, but not in Caiman. A nuclear column, apparently homologous with Clarke's column of mammals, was observed in Ctenosaura and Caiman. A somatotopically organized dorsal column projection to gracile and cuneate nuclei was found in Ctenosaura and Caiman. No evidence was obtained for a projection to a lateral cuneate nucleus or to areas rostral to the level of the dorsal column nuclei. The findings are contrasted with previous descriptions of dorsal root projections in reptiles, as well as with the pattern of dorsal root distribution reported for amphibians and for mammals.
The development of synaptic contacts in the cerebellum of Macaca mulatta
Authors: Kornguth Steven E. , Anderson John W. , Scott Grayson 
Published: January 2005

AbstractThe maturation of various cerebellar cortical cells, the appearance of afferent fibers to the cerebellum, and the development of synaptic contacts in the cerebellar cortex and deep nuclei was investigated in the fetal macaque. Ultrastructural studies were done on cerebellum obtained from fetuses at 75, 100, 125 and 150 days after conception to interrelate the temporal development of these three systems. At 75 days, synaptic contacts were seen on somas and axons of neurons in the deep cerebellar nuclei, and climbing fibers formed pericellular baskets around Purkinje cells. By 100 days the climbing fibers synapsed with somatic spines of the Purkinje cells, and mossy fiber endings were present in the internal granule cell layer. Synaptic contacts were also seen on dendritic processes of neurons in the deep cerebellar nuclei at this time. In the 125 day cerebellum, Golgi cells were identified for the first time and climbing fibers and parallel fibers made synaptic contact with both Purkinje and Golgi cells. At 150 days parallel fibers made synaptic contact with superficial stellate cells and mature cerebellar glomeruli had appeared. At this stage, axosomatic contacts of climbing fibers on the soma of Purkinje cells had disappeared. The relationship of these anatomical observations to possible functional activity is discussed.
An electron microscopic study of neurons during postnatal development of the rat cerebral cortex
Authors: Caley David W. , Maxwell David S. 
Published: January 2005

AbstractThe differentiation and maturation of the neurons of rat cerebral cortex during the first three weeks of postnatal life has been studied with the light and electron microscopes. At birth, the supeficial cortex is largely made up of undifferentiated cells, tightly packed together in vertical columns between which the developing process and blood vessels, and relatively extensive extracellular spaces are found. During the first two weeks, these cells diferentiate into either neuroblasts and neurons, or into spongioblasts and neuroglia. In the case of neurons but not neuroglia, this maturation occurs in a gradient from the depths toward the surface. The round undifferendtiated cells are characterized by an absence of processes, a thin rim of perinuclear cytoplasm containing few organelles, and a peripheral clumping of condensed nuclear chromatin. The differentiating neuroblasts display increasing numbers of cytoplasmic organelles, especially endoplasmic reticulum, evenly dispersed nuclear chromatin, and presumptive apical dendrites. The rough endoplasmic reticulum of neuroblasts become swollen during the transition into neurons during the second week. The endoplasmic reticulum forms subsurface cisterns that transiently evaginate the cell membrane, forming conspicuous diverticuli in the neuropil at the same time that the cells display an increase of cytoplasmic matrix density and increasing numbers of ribosomes. During the three weeks following birth, organelles increase in number and complexity, synapses develop, the extracellular spaces disappear, and the maturing neurons become separated from one another by the growth of neuropil and nonnervous elements. At the end of this three week period the cortical tissue and its neurons are apparently mature and the adult pattern of cortical fine structure is established.
Ventrolateral spinal cord afferents to the brain stem in the domestic pig
Authors: Breazile James E. , Kitchell Ralph L. 
Published: January 2005

AbstractThe distribution and termination within the brain stem of nerve fiber systems which comprise the ventrolateral funiculus of the spinal cord were studied in the domestic pig. Guillery et al. ('61) modification of the Nauta‐Gygax technique for silver impregnation of degenerating nerve fibers was utilized in this study. It is concluded that a spinothalamic tract does exist in the domestic pig, but that it is secondary in prominence to a large spinoreticular fiber system. The distribution and terminations of fibers within the brain stem of the pig resemble the pattern described by Anderson and Berry ('59) for the cat.
An electrophysiological study of the cerebellar projections to the nucleus ventralis lateralis of thalamus in the cat. I. Nuclei fastigii et interpositus
Authors: Angaut Pierre , Guilbaud Gisègle , Reymond Marie‐Claude 
Published: January 2005

AbstractStimulation of nucleus fastigii and interpositus of the cerebellum of the cat under chloralose anaesthesia evokes non‐relayed responses in the thalamic region including and surrounding n. ventralis lateralis (VL).Monosynaptic responses to stimulation of nucleus interpositus are only contralateral whereas those of n. fastigii are bilateral.Responses to fastigial stimulation appear in an area restricted to VL and n. ventralis medialis, contralateral projections being much more extensive than homolateral.Projections of n. interpositus extend widely upon VL and n. ventralis anterior encroaching on a small rostral area of nucleus ventralis posterolateralis; some fiber responses are also recorded up to a capsular zone close to globus pallidus.The results of the current study are discussed with regard to the data from anatomical and physiological literature.
Septohabenular connections in the rat, cat and monkey
Authors: Powell Ervin W. 
Published: January 2005

AbstractSeptohabenular projections were studied using the Nauta‐gygax method of staining degenerating axons. The results are in general agreement with those reported by others. However, the septum projects differentially to the habenula and the patterns differ slightly in the three species studied. Rostral parts of the septum projected to the lateral habenular nucleus and posterior parts to the medial nucleus. Dorsal and ventral structures of the septum had a slight dorsal ventral topography of projection in the stria medullaris thalami. Projection through the stria medullaris was confined to its medial part only in the rat. The largest number of fibers to bypass the habenula and terminate in the mesencephalic central gray occurred in the monkey.
The sympathetic trunks of a hibernator, the bat Myotis lucifugus
Authors: Webber Richard H. , Kallen Frank C. 
Published: January 2005

AbstractThe sympathetic trunks in Myotis lucifugus are each characterized by three unusually prominent ganglia: the superior cervical, the stellate and a “large lumbar” ganglion. The superior cervical appears to distribute only to the head region. The cervical sympathetic trunk connects with the vagus nerve but not to the cervical spinal nerves. The stellate is the largest of the trunk ganglia. A prominent nerve arising from it follows the vertebral artery. This vertebral nerve connects with the second to the seventh, and sometimes the eighth, cervical spinal nerves. Another prominent branch from this ganglion follows the cervical artery to ramify in the interscapular brown fat pad. The stellate ganglion supplies the brachial plexus directly and via the vertebral nerve. Its branches also supply thoracic viscera important for arousal from hibernation as well as for flight. The large lumbar ganglion contributes very few fibers to abdominal or pelvic viscera but, via the lumbosacral plexus, may affect vasoconstriction in the pelvic wall and posterior extremities. The prominent prevertebral ganglia in the abdomen and pelvis, which include an adrenal‐;renal complex, are probably supplied by the tenth thoracic to second lumbar spinal nerves.
The postnatal development of the canine cerebellar cortex
Authors: Phemister Robert D. , Young Stuart 
Published: January 2005

AbstractThe cerebellum of the neonatal puppy was found to be incompletely differentiated. Its gross dimensions were less than half those of the normal adult, and although major lobules were recognizable, folial development was rudimentary. Microscopically, the cortex on the second postnatal day was distinguished by a thick subpial external granular layer of actively dividing cells. Beneath this transient layer, permanent cortical layers were largely undeveloped and myelination was not yet evident. During the first two postnatal weeks, the width of the external granular layer remained relatively constant (at slightly more than 50 μ), while other cortical layers underwent considerable growth, with histologic and cytologic differentiation. After the second postnatal week, the width of the external granular layer declined steadily, so that by the tenth week only a vestige of the layer remained. Between the second and seventy‐second postnatal days, a tenfold increase occurred in the width of the molecular layer. Major growth and differentiation also occurred in the internal granular layer, which became almost tripled in its width during the first ten postnatal weeks. Myelination proceeded in a centrifugal direction and occurred earlier in the vermis than in the hemispheres. By the end of the first month, myelination of the vermis was practically complete, and by the tenth week, the arbor vitae of the hemispheres appeared fully myelinated.
The cytoarchitecture of the human anteroventral cochlear nucleus
Authors: Bacsik Robert D. , Strominger Norman L. 
Published: January 2005

AbstractThe cytoarchitecture of the anteroventral cochlear nucleus (Av) was studied in six human brain stems stained with cresyl violet. A compensating polar planimeter was used to measure the cross‐sectional area of perikarya drawn with a camera lucida device. The majority of neurons are ovoid in shape with somewhat eccentric nuclei and moderately coarse Nissl granules which are uniformly distributed throughout the neuroplasm. On a dimensional basis, there is a single population of cells which vary in size according to a normal distribution. The average perikaryal size is 370 sq. μ (18 × 26 μ). Cellular density is greatest along the lateral margin of Av near the rostral end. Neurons of all sizes intermingle in every part of the nucleus and no circumscribed area can be characterized as containing exclusively or even predominantly neurons of any given size. The cytoarchitecture of the human anteroventral cochlear nucleus so closely resembles that of the rhesus monkey as to suggest similar fiber projections and physiological properties in both species.
Distribution of cerebellar and somatic lemniscal projections in the ventral nuclear complex of the Virginia opossum
Authors: Walsh T. Myrick , Ebner Ford F. 
Published: January 2005

AbstractThe distributions of cerebellar and somatic lemniscal projections to the ventral nucleus of the thalamus were compared in the opossum to determine the extent of overlap in the terminal field of these two fiber systems. Following lesions of these structures, the degenerated fibers were traced to the thalamus using the Fink‐Heimer technique. The results indicate that the cerebellum projects only to the rostral portion of the ventral nucleus, while the gracile and cuneate nuclei project to the caudal portion of the ventral nucleus. We conclude from comparing these two afferent fiber systems that there is no detectable overlap in the cerebellar and lemniscal projections to the ventral thalamic nucleus of the opossum. These results support the hypothesis that the single somatic sensory‐motor area of the opossum's cortex receive afferent fibers from at least two separate subdivisions of the ventral nucleus. Outside the border of the ventral nucleus, cerebellar and lemniscal projection fields do overlap, especially in a cell group just dorsal to the ventral posterior nucleus. This is a distinctly different type of organization of these afferent fiber systems. This cell group has recently been shown likewise to project to the parietal somatic sensory‐motor cortex. Since the mode of intracortical termination of this projection differs markedly from that of the VP and VAL projections, the somatic sensory‐motor cortex of the opossum can be said to receive fundamentally different projections from two thalamic regions both of which are recipients of both cerebellar and somatic‐lemniscal information.
Retinal structure in the smooth dogfish, Mustelus canis: Light microscopy of bipolar cells
Authors: Witkovsky Paul , Stell William K. 
Published: January 2005

AbstractRetinal bipolar cells of the smooth dogfish (Mustelus canis) were examined in the light microscope after vital staining with methylene blue or in Golgi‐impregnated preparations. Bipolars of Mustelus retina, as of other vertebrate retinas, were divisible into two broad categories: those with fine axons and those with bulbous axonal terminals. Further classification was made on the basis of the level of axonal termination within the inner synaptic layer (ISL). The wide, monostratified axons of some bipolar cells (type a1) ramify in the distal (outer) third of the ISL to a total horizontal span of 400–600 μm. These cells possess elliptical dendritic arbors 80–100 X 150–200 μm in diameter, variously shaped perikarya, and a cylindrical or bulbous Landolt's club. In flatmounted preparations, these cells often are seen to have all dendrites exiting horizontally from one side of the perikaryon, the axon exiting horizontally from the other side. The narrow, multistratified axons of a second class of bipolars (type a2) ramify within the distal half of the ISL to a horizontal span of 45–130 μm. Their dendritic arbors are round or elliptical and of a diameter similar to that of axonal spread. A filamentous or flask‐shaped Landolt's club is generally present. The axons of bipolars with bulbous axonal terminals (type b) end in the middle of the ISL. The perikaryon is tulip‐shaped and a circular dendritic arbor, 70–100 μm in diameter, spreads concentrically about it. These cells always lack a Landolt's club. In the proximal (inner) half of the ISL, both wide monostratified (type c1) and narrow multistratified (type c2) bipolar cell axons are encountered. The axons of cells which have monostratified endings in the proximal ISL (type c1) branch more frequently and have lesser horizontal extents than the axons of their counterparts (type a1) in the distal ISL. All bipolars ending in the proximal ISL lack a Landolt's club. The thick ISL of Mustelus retina is divided into at least three vertical sub‐layers, within each of which terminate axons of one or two classes of bipolar cells and dendrites of a single class of giant ganglion cells. If giant ganglion cells receive direct synaptic input from bipolar cells, the vertical strata of the ISL contain structurally distinct, and perhaps functionally different, bipolar‐ganglion cell pathways.
Projections of cervicothoracic dorsal roots to the cuneate nucleus of the rat, with observations on cellular “bricks”
Authors: Basbaum Allan I. , Hand Peter J. 
Published: January 2005

AbstractThe distribution of cervicothoracic (C1–T2) dorsal roots to the cuneate and accessory cuneate nuclei was studied in the rat with the Fink‐ Heimer I technique following single extradural rhizotomies. Cytoarchitectural analysis of the cuneate nucleus revealed an anatomically distinct caudal and rostral region. The caudal region was characterized by discrete aggregates of cells arranged as “slabs” or “bricks” which continue vertically almost to the ventral limit of the cuneate nucleus. In contrast, the cells of the rostral region were organized in a non‐focal manner.The projection of the cervicothoracic dorsal roots to the cuneate nucleus reflected the cytoarchitectural pattern observed; non‐focal terminal fields of degeneration in the rostral region and discrete “terminal field bands” of degeneration isolated from one another by degeneration‐free zones in the caudal region. However, the projections of dorsal roots C5 and T2 to the caudal region is non‐focal.In both regions of the cuneate nucleus, the distribution of dorsal root degeneration was topographically organized with cranial roots terminating ventrolaterally and more caudal roots, dorsomedially. The amount of intersegmental overlap of dorsal root terminal fields was greater in the rostral than in the caudal region.Individual dorsal roots projected differentially to the two regions of the cuneate nucleus. Roots C3 and C4 distributed primarily to the rostral region whereas C5 to T1 distributed to both regions. T2 root projected primarily to the caudal region. Dorsal roots C1 and C2 did not terminate in either region of the cuneate nucleus.All roots studied projected heavily and topographically to the accessory cuneate nucleus. Extensive overlap of the very dense terminal fields characterized the dorsal root projections to the accessory cuneate nucleus.On the basis of cytoarchitectonics and dorsal root projections, a dual organization of the cuneate nucleus was revealed. This organization reflected previous anatomical and electrophysiological studies in the rat and paralleled the organization described in the dorsal column nuclei of the cat. The significance of the dual organization with respect to dorsal column function was discussed, as was the finding of the lack of C1 and C2 dorsal root projections to the cuneate nucleus.
Investigation of glial cells in semithin sections. II. Variation with age in the numbers of the various glial cell types in rat cortex and corpus callosum
Authors: Ling Eng‐Ang , Leblond C. P. 
Published: January 2005

AbstractSemithin Epon sections stained with toluidine blue were used to enumerate astrocytes, microglia, the three subtypes of oligodendrocytes, and cells referred to as free subependymal cells, in the corpus callosum and cerebral cortex of male Sherman rats of various ages. The period covered extended from a few days before weaning (3/4 month of age) until the time when growth became negligible (5 months of age).The total number of glial cells increases with age in both cortex and corpus callosum. However, the investigation of individual cell types reveals that the number of microglia remains fairly constant throughout the period under study. The number of astrocytes in corpus callosum increases up to the age of one month, but remains constant thereafter, while their number in the cortex is the same at all investigated times. In the case of oligodendrocytes, the three subtypes behave differently. About two‐thirds of the oligodendrocytes in rats aged three‐quarters of a month are of the light or medium shade types, but the number of these gradually decreases with age and becomes very low in five‐month‐old rats. In contrast, the dark cells which constitute about one‐third of the oligodendrocytes in young rats make up nearly the whole of this group in adults. Finally, free subependymal cells are absent in cortex throughout the period under study, but are present in corpus callosum, where their number steadily declines with age.In conclusion, the numbers of astrocytes and microglia seem to remain constant in growing rats after the age of one month. Dark oligodendrocytes markedly increase in number with age, while the other types of oligodendrocytes and the free subependymal cells are reduced to negligible numbers by the age of five months.
Vestibular cortical projection in the rabbit
Authors: Ödkvist L. M. , Rubin A. M. , Schwarz D. W. F. , Fredrickson J. M. 
Published: January 2005

AbstractThe neocortical surface of the rabbit's brain was explored by macroelectrodes with isolated electrical stimulation of the vestibular nerve. Surface positive evoked potentials were recorded within the first somatosensory (SI) forelimb field. Negative field potentials in middle cortical layers were only found in a small area within the rostral part of this field. The rabbit's vestibular field is compared with those of rodents, carnivores and primates.
Experimental reorganization of the cerebellar cortex. IV. Parallel fiber reorientation following regeneration of the external germinal layer
Authors: Altman Joseph 
Published: January 2005

AbstractThe heads of Long‐Evans hooded rats were irradiated with a schedule of low‐level x‐ray which allowed regeneration of the external germinal layer. In the subsequently regenerated molecular layer, parallel fibers were often reoriented. In some cerebella this was restricted to a single lobule, frequently several lobules were affected, rarely almost the entire vermis. It was postulated that the reorientation of parallel fibers was determined by the invasion route of multiplying cells from spared foci of the external germinal layer. Where parallel fibers were rotated transversely, the axons of basket cells and the arborizing dendrites of Purkinje cells became oriented longitudinally. This, and other considerations indicated that parallel fibers exert a guiding influence on the pattern of growth of the spiny branchlets of Purkinje cells.