bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postnatal development of the cerebellar cortex in the rat. III. Maturation of the components of the granular layer
Authors: Altman Joseph 
Published: December 2004

AbstractThe migration of granule cells and the maturation of the various elements of the granular layer were studied in the cerebellar cortex of rats aged 0, 3, 5, 7, 10, 12, 15, 21 and 30 days with histological, histochemical, autoradiographic and electron microscopic techniques. The bulk of the granule cells are formed during the second week, but due to the time required for their migration and the lag in the formation of dendrites, few glomerular synapses are formed with mossy fibers before the beginning of the third week and the process is still in progress at 30 days, long after the dissolution of the external germinal layer. The maturation of Golgi cells is a protracted process. Their axons synapse with granule cell dendrites as soon as the glomeruli begin to mature. Evidence was obtained that mossy fibers synapse with the dendrites of Golgi cells. Towards the end of the second week the Lugaro cells are formed and synapses appear on their somata during the third week. Among these synapses the recurrent collaterals of Purkinje cell axons were identified. The Lugaro cells may be the primary targets of the infra and supraganglionic plexuses formed by these collaterals. In conclusion it was suggested that there are three major, successive stages in the neurogenesis of the cerebellar cortex, the morphogenic, synaptogenic and gliogenic. However, in the large Purkinje cell the synaptic maturation of one region (the soma) may begin before the morphogenic and synaptogenic maturation of the entire cell (the dendrites) is completed.
Functional significance of the fibrous laminae in the ventrobasal complex of the thalamus of slow loris
Authors: Krishnamurti A. , Kanagasuntheram R. , Wong W. C. 
Published: December 2004

AbstractInvestigations on the thalamocortical relationships were carried out on nine slow lorises. The electrophysiological data obtained from our previous experiments on the somatotopic organization within the Sm I and Sm II cortical regions were utilized for the placement of selective cortical ablations. The thalamic regions exhibiting retrograde degenerative changes were reconstructed. The projection of fibres to the electrophysiologically defined Sm I cortex is largely confined to the ventrobasal complex of the thalamus. Moreover, this region of the thalamus in slow loris is subdivided into a lateral, an intermediate and a medial portion by two main fibrous septa. The medial septum is found between the pars medialis and pars lateralis of the ventrobasal complex separating the head representation from the forelimb representation while the lateral septum, situated within the pars lateralis delineates the forelimb representation from that of the hind limb. A correlation is found to exist between these fibrous septa and the limiting sulci found within the somatic‐sensory cortex separating functional subdivisions. Moreover, a group of cells lying ventromedial to the pars medialis showed degenerative changes in the material where Sm II cortical region was ablated indicating the projection from this group of cells of at least some fibres to the second somatic‐sensory cortex. Another interesting feature that emerged from the results of the present study is the possible connection of n. subparacentralis with the paleoclaustrum, and/or the overlying allocortex.
Spino‐bulbar, spino‐thalamic and medial lemniscal connections in the american opossum, Didelphis marsupialis virginiana
Authors: Hazlett James C. , Dom Richard , Martin George F. 
Published: December 2004

AbstractProjections from the spinal cord and dorsal column nuclei to more rostral levels of the neuraxis were investigated in seventeen adult opossums by the Nauta‐Gygax and Fink‐Heimer techniques. In all cases with spinal cord lesions a greater number of degenerating fibers distributed to the medulla and pons than to the midbrain and diencephalon. Numerous degenerating fibers ended within the medial reticular formation of the medulla and caudal pons, and within the lateral reticular formation of the rostral pons and midbrain. Degenerating fibers were numerous in the reticular formation following cervical and thoracic lesions, but sparse in specimens with damage restricted to either the lumbar or sacral spinal cord. The dorsal column nuclei received afferent connections from the well known dorsal funicular pathway and, although to a much lesser extent, from the main ventrolateral spinal bundle. Although most of the latter fibers ended in the subnucleus dorsalis and spinal vestibular nucleus, some penetrated into the gracile and cuneate nuclei. Conspicuous terminal degeneration was present within the inferior olivary nucleus following cervical and thoracic lesions, but was lacking in cases of either caudal lumbar or sacral cord lesions. The location of terminal degeneration within the lateral reticular nucleus is dependent upon the level of the lesion in the spinal cord. Degenerating fibers ended within the lateral vestibular nucleus in all cases of spinal cord hemisection, and within the medial portion of the facial nucleus in cases with a lesion rostral to C‐4. After cervical and thoracic hemisections terminal fiber degeneration was present within the midbrain tegmentum, the periaqueductal gray, the intercollicular nucleus (Mehler,'69), the posterior thalamic nucleus, the ventrobasal nucleus, the parafascicular nuclei and the caudal nucleus ventralis lateralis. All thalamic nomenclature was taken from Oswaldo‐Cruz and Rocha‐Miranda, '68. In animals with more caudal lesions, no fiber degeneration was evident within the nucleus ventralis lateralis and so little within the ventrobasal nucleus that it was impossible to ascertain a somatotopic pattern of spinothalamic projections.Lesions of the dorsal column nuclei caused terminal degeneration within the inferior olivary nucleus, the pars lateralis of the nucleus of the inferior colliculus, the zona incerta, the posterior thalamic nucleus, the caudal part of the ventral lateral thalamic nucleus and the ventrobasal nucleus of the thalamus. Diffuse connections with the reticular formation, periaqueductal gray, midbrain tegmentum and the parafascicular complex were also observed. The results from small lesions indicate that the input to the ventrobasal nucleus in the opossum is organized in the typical mammalian fashion.
Morphogenesis of the cerebellum of the frog tadpole during spontaneous metamorphosis
Authors: Gona Amos G. 
Published: December 2004

AbstractThe cerebellum of the frog tadpole remains in an immature state throughout the premetamorphic (growth) phase. An external granular layer is absent except for a few scattered cells. A well defined Purkinje cell zone is also lacking. Large cells, which presumably are the immature Purkinje cells, are found in the subventricular zone.During the prometamorphic period (accelerated hind leg growth) an external granular layer, several cells thick, becomes established by a migration of cells from the base of the cerebellum. A second migration involving the movement of the external granule cells toward the ventricular region begins at this time. However, the most active period of this latter migration is at the end of the prometamorphic period and during the days following fore leg emergence, viz., metamorphic climax. Concomitantly, a well defined Purkinje cell stratum is established.
Autonomic neurons in the spinal cord of the rhesus monkey: A correlation of the findings of cytoarchitectonics and sympathectomy with fiber degeneration following dorsal rhizotomy
Authors: Petras J. M. , Cummings J. F. 
Published: December 2004

AbstractCytoarchitectonic study of cell groups in the zona intermedia of the spinal cord led to the identification of the following nuclei in the rhesus monkey: n. intermediolateralis thoracolumbalis pars principalis et funicularis (ILp, ILf); n. intercalatus spinalis (IC); n. intercalatus pars paraependymalis (ICpe); n. intermediomedialis (IM); n. intermediolateralis sacralis pars principalis et funicularis (ILSp, ILSf); n. intercalatus disseminata (ICd); and n. torsade. Unilateral thoracic or abdominal sympathectomy, or both, performed in a second group of macaques, resulted in massive numbers of chromatolytic preganglionic neurons in IC, ILp and ILf. In the third group of macaques, dorsal rhizotomy followed sympathectomy. Fiber degeneration in these cases was stained with the Nauta and Fink‐Heimer methods. Despite variations in survivaltime and staining methods, no evidence was found for dorsal root terminal connections with the somata or proximal dendritic stems of chromatolytic sympathetic or parasympathetic visceral motor neurons (IC, ILp, ILf, ILSp, ILSf) although the same cases contained terminal fibers in n. marginalis of Waldeyer, substantia gelatinosa of Rolando, n. proprius cornus dorsalis (Pd), Clarke's column, n. intermediomedialis (IM) and among axial and appendicular somatic motor neurons. The present anatomical data suggest that, within the spinal cord, visceral reflex pathways are polysynaptic. Neurons in two or more spinal cell groups, IM, Pd and Cb (central basilar area of the dorsal horn) perhaps act as intermediary cells connecting dorsal root visceral afferent fibers with visceral motor (preganglionic) neurons. The visceral reflex pathway thus described includes a four neuron chain: dorsal root cell; IM, or Pd neuron, or both; preganglionic neuron; and the postganglionic neuron of the sympathetic system in the paravertebral or collateral ganglia, or the parasympathetic postganglionic neuron lying more distally.It was also found that many preganglionic neurons of the ILp, ILf and IC cell groups are as large as somatic motor neurons. Furthermore, the impression gained in this study is that visceral motor neurons appear in far greater numbers than somatic motor neurons.
Early neuron differentiation in the mouse olfactory bulb. II. Electron microscopy
Authors: Hinds James W. 
Published: December 2004

AbstractDifferentiating mitral cells were followed in serial section analysis of mouse embryos from day 12 of gestation (E12) to E14. Animals at E11 and E15 were also examined. Olfactory nerve axons reach the presumptive olfactory bulb at E12 and many penetrate deeply into the intermediate (mantle) layer at this time. The first identified young neurons (postmitotic neuroblasts) were also seen at E12. Many had a tangential orientation, and they occurred only in the region where olfactory nerve axons were present. Olfactory nerve axons (and also mitral cell axons formed later) are characterized by numerous longitudinallyoriented microtubules and an extensive system of transversely and longitudinallyorinted cisternae of smooth endoplasmic reticulum (SER). Near the growing tips of olfactory nerve axons, the microtubules disappear and the SER becomes more extensive and irregular.The four stages of early mitral cell differentiation determined in the companion paper (Hinds, '72) were confirmed by electron microscopic analysis. In the earliest cells of the primitive radial stage few organelles occur in the perikaryon, but in later cells of this stage and in cells of the pre‐axonic tangential stage a Golgi complex and a pair of centrioles occurs on one side of the nucleus at the base of the largest tangential process, thus determining a cell polarity within the tangential plane. This initial polarity at E12 seems to be random and unrelated to the polarity attained when axon outgrowth occurs at E13 and E14, suggesting a re‐orientation prior to axon outgrowth. The growing tips of primitive tangential processes were studied and compared with those of growing primitive radial processes and growing axons.
Laminar and columnar distribution of geniculo‐cortical fibers in the macaque monkey
Authors: Hubel David H. , Wiesel Torsten N. 
Published: December 2004

AbstractSingle cell recordings in monkey striate cortex have shown differences in response properties from one cell layer to the next and have also shown that the IVth layer, which receives most of its input from the geniculate, is subdivided into a mosaic of regions, some connected to the left eye, others to the right. In the present study small lesions were made in single layers or pairs of layers in the lateral geniculate body, and the striate cortex was later examined with a Fink‐Heimer modification of the Nauta method. We hoped to correlate the laminar distribution of axon terminals in the cortex with functional differences between layers, and to demonstrate the IVth‐layer mosaic anatomically.After lesions in either of the two most dorsal (parvocellular) layers, terminal degeneration was found mainly in layer IVc, with a second minor input to a narrow band in the upper part of IVa. A very few degenerating fibers ascended to layer I. In contrast, lesions in either of the two ventral (magnocellular) layers were followed by terminal degeneration confined, apparently, to IVb, or at times extending for a short distance into the upper part of IVc; no degeneration was seen in layer IVa or in layer I.After a lesion confined to a single geniculate layer, a section through the corresponding region of striate cortex showed discrete areas or bands of degeneration in layer IV, usually 0.5–1.0 mm long, separated by interbands of about the same extent in which there was no terminal degeneration. When serial sections were reconstructed to obtain a face‐on view of the layer‐IV mosaic, it appeared as a series of regular, parallel, alternating degeneration‐rich and degeneration‐poor stripes. When a geniculate lesion involved both layer VI (the most dorsal, with input from the contralateral eye) and the part of layer V directly below (ipsilateral eye), the cortical degeneration, as expected, occupied a virtually continuous strip in layer IVc and the reconstructed face‐on view of this layer showed a large confluent region of degeneration.In some of the reconstructions the cortical stripes seemed highly regular; in others there was a variable amount of cross connection between stripes. The stripes varied in width from 0.25 to 0.50 mm, and width did not seem to correlate with region of retinal representation.It is concluded that the long narrow stripes of alternating left‐eye and right‐eye input to layer IV are an anatomical counterpart of the physiologically observed ocular‐dominance columns. Because of this segregation of inputs, cells of layer IV are almost invariably influenced by one eye only. A cell above or below layer IV will be dominated by the eye supplying the nearest IVth layer stripe, but will generally, though not always, receive a subsidiary input from the other eye, presumably by diagonal connections from the nearest stripes supplied by that eye.
Experimental Studies on hatching behavior in the Chick. III. The role of the midbrain and forebrain
Authors: Oppenheim Ronald W. 
Published: December 2004

AbstractVarious portions of the midbrain and forebrain of chick embryos were ablated by microsurgical techniques at early prefunctional stages of incubation (38–45 hours) in an attempt to assess the role of these parts of the nervous system in early embryonic motility and in later prehatching and hatching behavior.Embryos with the entire telencephalon and anterior diencephalon removed (total FB) exhibited no behavioral defects until about 20 days of incubation, at which time they were unable to initiate the final climax stage of hatching, in which the embryo normally cracks the shell around the circumference and emerges or hatches. On the other hand, embryos with no diencephalic damage and with sparing of parts of the cerebral hemispheres, were able to initiate the final climax stage, and actually manage to hatch (partial FB).Removal of only the dorsal part of the midbrain (primarily the primordia of the optic lobes) resulted in no behavioral deficits until after hatching. These embryos (partial MB) exhibited completely typical prehatching and hatching behavior. However, a complete gap in the midbrain region, separating the forebrain from the hindbrain, precluded all prehatching and hatching behavior. These embryos continued to exhibit behavior more characteristic of early (pre 16 day) embryonic stages and never managed to hatch.The possibility was discussed that the basic coordinated motor pattern utilized during prehatching and hatching stages (Type III activity) is organized in the hind‐ or mid brain area, but that in order for the final climax stage of hatching to be initiated and maintained, facilitation (or a more direct influence) from either (or both) the anterior diencephalon, or the caudal and basal parts of the telencephalon is needed.
The number of Purkinje cells and inferior olivary neurones in the cat
Authors: Mlonyeni Maxwell 
Published: December 2004

AbstractIt is generally assumed that (i) all neurones of the inferior olive send their axons to the cerebellum; (ii) the fibers from the olive end as climbing fibers; (iii) one climbing fiber establishes extensive synaptic contact with one Purkinje cell. From this it has been inferred that there is one inferior olivary neurone per Purkinje cell. The number of neurones in both inferior olives from four cats have been counted in histologic sections. The totals obtained are 145380, 127270, 126920 and 121360, respectively. In two of the cats the Purkinje cells were counted. The ratios of inferior olivary neurones to Purkinje cells were found to be 1 : 10 and 1 : 11, respectively.
Time differences in the formation of the receptor types in the developing chick retina
Authors: Morris Valerie B. 
Published: December 2004

AbstractThe times at which the receptor types completed their final S phase was measured by injecting 3H‐thymidine at a series of incubation times and then rearing the embryos to hatching. Incorporation of 3H‐thymidine by the developing receptors was examined, subsequently, in EM autoradiographs of differentiated receptors whose type could be identified. The time at which each receptor type completed final S was estimated from the proportions unlabelled at each of the times at which 3H‐thymidine was injected. The incubation time at which 50% of the receptor type had completed final S was 134.2 hours for principal cones, 139.5 hours for rods, 145.6 hours for single cones and 153.5 hours for accessory cones. It is unlikely, from these estimates, that a principal cone, rod, single cone and an accessory cone, which constitute the repeating group in the retinal mosaic pattern in the periphery, are formed from one stem cell. Each receptor type in a repeating group is probably formed, in the final cell cycle, from a different precursor cell.
Postjunctional membrane specialization at cholinergic myoneural junctions in the leech
Authors: Rosenbluth Jack 
Published: December 2004

AbstractMyoneural junctions are described in the body musculature of the leech. Although similar to cholinergic junctions elsewhere, these exhibit a distinctive postjunctional membrane specialization consisting of discrete, concave patches, occupying a small proportion of the total postjunctional area, at which both the inner and outer surfaces of the membrane appear to be coated. The outer coating consists of a hexagonal array of projections which arise from the outer dense lamina of the plasma membrane and extend into the junctional cleft. The projections are spaced at intervals of ∼ 150 Å and are thickened at their tips. The inner dense lamina of the membrane is coated by an amorphous cytoplasmic material. Details of this specialization show up well in specimens that have not been post‐osmicated but are stained (in sections) with permanganate and uranyl acetate. It is hypothesized that the morphologically specialized patches are composed of units containing the acetylcholine receptors.
Autoradiographic localization of hormone‐concentrating cells in the brain of the female rhesus monkey
Authors: Pfaff Donald W. , Gerlach John L. , McEwen Bruce S. , Ferin Michel , Carmel Peter , Zimmerman Earl A. 
Published: December 2004

AbstractWith autoradiographic procedures, cells which bind 3H‐estradiol were found in preoptic, hypothalamic and limbic structures in the brains of ovariectomized, adult female rhesus monkeys. Estrogen‐binding cells were seen in the medial preoptic area, medial anterior hypothalamus, ventromedial nucleus, and especially heavy labelling was seen throughout the extent of the arcuate (infundibular) nucleus of the hypothalamus. In limbic structures, cells in the bed nucleus of the stria terminalis and in the medial nucleus of the amygdala were well labelled. Systematic charting also revealed smaller numbers of estrogen‐concentrating cells in other specific hypothalamic and limbic locations. In the anterior pituitary, significant numbers of basophils and acidophils were found to bind estrogen. Pars intermedia and the posterior lobe were virtually unlabelled. In the uterus, heavily labelled cells were seen in the endometrial stroma and in the myometrium. These autoradiographic findings agree with results of parallel biochemical experiments.In monkeys injected with 3H‐corticosterone, the most extensive high‐intensity binding found with autoradiography was in the hippocampus. Both pyramidal neurons and dentate gyrus granule cells were labelled. Biochemical experiments, also, showed highest cell nuclear accumulation of corticosterone in the hippocampus.Findings with estradiol in the rhesus monkey extend to primates conclusions based on autoradiographic experiments with steroid sex hormones in a wide variety of vertebrates, including fish, amphibians, birds, and various mammalian species (Morrell et al., '75a). All of these vertebrate forms have sex hormone‐concentrating neurons, which are found in specific preoptic, hypothalamic and limbic structures. In the species studied, such hormone‐concentrating neurons appear to be involved in the hormonal control of behavioral and pituitary function.
The accessory optic system of the ferret
Authors: Thorpe Penelope A. , Herbert J. 
Published: December 2004

AbstractThe accessory optic system of the ferret has been studied both by silver degeneration staining and by autoradiography after intraocular 3H leucine injections. There is no anterior accessory optic tract but a posterior tract containing only crossed fibres leaves the brachium of the superior colliculus and ends in the two nuclei, the medial and lateral terminal nuclei, lying either side of the cerebral peduncle. Both suprachiasmatic nuclei receive retinal fibres visible only on autoradiographs; most fibres end in the contralateral nucleus. No other area in the hypothalamus appears to receive retinal fibres demonstrated by these methods.