bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postnatal differentiation of cell body volumes of spinal motoneurons innervating slow‐twitch and fast‐twitch muscles
Authors: Sato Manabu , Mizuno Noboru , Konishi Akira 
Published: December 2004

AbstractDistribution of cell body volumes of motoneurons innervating the soleus (slow‐twitch or tonic) and medial gastrocnemius (fast‐twitch or phasic) muscles was examined in adult cats and a series of kittens ranging from one to 140 days in age. To identify the soleus (Sol) and the medial gastrocnemius (MG) motoneurons, each group of motoneurons was labeled differentially by utilizing retrograde axonal transport of horseradish peroxidase injected into the muscles.It was verified statistically that in the adult cat, the mean cell body volume of the Sol motoneurons was smaller than that of the MG motoneurons. Difference of the mean cell body volume between the Sol and MG motoneurons was found to be significant around the tenth postnatal day. The mean cell body volumes of both Sol and MG motoneurons increased mainly during the third to the seventh week after birth. After this period, increase of the cell body volume was relatively slight and in the fifth month after birth, some of the motoneurons still appeared to be growing. Our findings also suggested that the MG motoneurons may exhibit the adult pattern of distribution of cell body volume in an earlier postnatal stage than do the Sol motoneurons, and that differentiation of motoneurons into the gamma and alpha types may occur earlier than differentiation into the tonic and phasic types.
Growth of the corticospinal tract and the development of placing reactions in the postnatal rat
Authors: Donatelle Janet Marie 
Published: December 2004

AbstractThe growth of corticospinal axons into the spinal cord has been demonstrated using the autoradiographic and the Fink‐Heimer silver degeneration methods. In addition, the development of several types of placing reactions has been studied. After unilateral injections of radioactive proline or unilateral injections of radioactive proline or unilateral ablations of the somatosesory‐motor cortex, corticospinal axons were found to extend into the contralateral dorsal funiculus of the lower cervical cord at one day postnatally, into mid‐thoracic segments at three days, into upper lumbar cord by five days and into coccygeal segments by nine days. Corticospinal axons are first present in the contralateral spinal gray of lower cervical cord at day 5 and in the contralateral spinal gray of lower lumbar and sacral cord by day 9. Little change in the topographical distribution or in the density of the projection is found at all levels of the spinal gray after the fourteenth postnatal day. Comparable results were found with both experimental techniques.Forelimb placing is first seen between 4 to 7 days and hind limb placing between 9 to 13 days. The last placing response to appear in both the forelimbs and the hindlimbs is placing in response to tactile and light proprioceptive stimuli. After the initial onset of the placing reactions, there is a gradual increase in the frequency and speed of the responses until 14 to 17 days postnatally, at which time the reactions appear to be mature.While a causative relationship between the growth of corticospinal axons into the spinal cord and the development of placing has not been established, a close temporal relationship has been found between first: the appearance of fore‐ or hindlimb placing responses and the appearance of corticospinal axons within the spinal gray at the appropriate levels of the cord and second: between the completion of the primary growth of corticospinal axons at the light microscopic level and the maturation of the placing reactions.
Anatomical and neurobehavioral investigations concerning the thalamo‐cortical organization of the rat's visual system
Authors: Hughes Howard C. 
Published: December 2004

AbstractThe organization of thalamic afferents to the rat's visual cortex was investigated autoradiographically and through the retrograde transport of horseradish peroxidase (HRP) following injections into striate and peristriate cortex. The results revealed that Nucleus lateralis posterior (NLP) projects to a large peristriate cortical field that includes areas 18A, 7, and the anterior portion of area 18, and to a circumscribed temporal area corresponding to Krieg's ('46a,b) area 20. The dorsal lateral geniculate nucleus (LGNd) was shown to project to two spatially discontinuous cortical areas. The largest geniculate receiving area is partially coextensive with Krieg's area 17, but an extension of this projection posterior and medial to the striate cortex was found. In addition, a geniculate projection to a restricted field located in the lateral peristriate cortex was identified.Concurrent investigations were designed to assess the pattern discrimination abilities of rats prepared with striate cortical ablations, lesions in NLP and combined striate‐cortical and thalamic ablations. Comparison of these animals with normal control subjects revealed that the striate cortex in the rat (as in the cat [Doty, '71; Sprague et al., '77] and the tree shrew [Killackey and Diamond, '71; Ware et al., '74]) is not necessary for successful pattern discrimination, and that the geniculo‐striate and NLP‐extra‐striate projection systems are both involved in mediating the visual discriminative abilities of the rat.The results add species generality to the concept that the central connections to the visual cortex are characterized by parallel‐conducting thalamic channels and contribute to the growing number of demonstrations that the extra‐striate cortex and associated thalamic cell groups contribute significantly to the process of visual‐pattern recognition.
The nucleus corporis pontobulbaris of the North American opossum
Authors: Martin G. F. , Linauts M. , Walker J. M. 
Published: December 2004

AbstractThe nucleus of the pontobulbar body (PBu) in the North American opossum is located, for the most part, adjacent to the motor root of the trigeminal nerve. Material prepared by degeneration and autoradiographic methods shows that the PBu receives projections from the facial motor‐sensory cortex, red nucleus, spinal cord and cerebellum. The latter fibers probably take origin within the fastigial nucleus. Each of the afferent connections ends in a restricted part of the PBu, but there is considerable overlap. Use of the horseradish peroxidase technique reveals that the PBu projects to the spinal cerebellum (anterior lobe, pyramis and paramedian lobules), to visual‐auditory areas of the vermis and to the lobus simplex as well as to crus I and II of the hemispheres. Although there is some topography to such projections, it is not sharply defined and many regions of the PBu contain labelled neurons after injections of horseradish peroxidase into widely separate areas of the cerebellar cortex.Because of its embryogenesis and position, the PBu is often considered part of the dorsolateral basilar pons. It appears from our material, however, that the organization of PBu afferent and efferent connections is different from that of the adjacent basilar pons, and arguments for considering the PBu a separate precerebellar nucleus are presented.
Size, laminar and columnar distribution of efferent cells in the sensory‐motor cortex of monkeys
Authors: Jones E. G. , Wise S. P. 
Published: December 2004

AbstractThe cells of origin of cortico‐cortical and subcortical projections from the subfields of the somatic sensory area and from the motor cortex have been identified in cynomolgus and squirrel monkeys by the retrograde axonal transport method.The somata of the cells of origin of a particular fiber system have a specific laminar or sublaminar distribution. The somata of the majority of cortico‐cortical cells lie in the supragranular layers. Those projecting to the opposite cortex are confined to the deeper half of layer III (layer IIIB). Ipsilateral cortico‐cortical neurons lie mainly superficial to them in layers IIIA and II, but in the second somatic sensory area (SII) and in area 2 of the first (SI), small numbers are also found in layer V. Corticospinal cells lie in the deeper part of layer V and corticostriatal cells in the superficial part. Corticopontine, corticobulbar and corticorubral cells lie in between. The majority of corticothalamic cells lies in layer VI but a second, smaller population is found in the deep part of layer V.The cells giving rise to a particular set of efferent connections can be distinguished in terms of size and, with the exception of the corticospinal cells, their size does not vary greatly from area to area. In many cases, the size and laminar specificity indicates that cells sending axons to one site cannot have collateral branches projecting to another.In most of the fiber systems studied, labeled cells form single or multiple strips, 0.5–1 mm wide and oriented mediolaterally across the cortex. The strips appear in all of the subfields of the somatic sensory and motor areas and may form the basis of the clustering of like groups of efferent neurons demonstrable in physiological studies.
Topographic projections between the nucleus isthmi and the tectum of the frog rana pipiens
Authors: Gruberg Edward R. , Udin Susan B. 
Published: December 2004

AbstractThe connections between the nucleus isthmi and the tectum in the frog have been determined by several anatomical techniques: iontophoresis of horseradish peroxidase into the tectum, iontophoresis of 3H‐proline into the nucleus isthmi and the tectum, and Fink‐Heimer degeneration staining after lesions of the nucleus isthmi. The results show that the nucleus isthmi projects bilaterally to the tectal lobes. The ipsilateral isthmio‐tectal fibers are distributed in the superficial layers of the tectum, coincident with the retinotectal terminals. The contralateral isthmio‐tectal fibers travel anteriorly adjacent to the lateral optic tract and cross the midline in the supraoptic ventral decussation, where they turn dorsally and caudally; upon reaching the tectum, the fibers end in two discrete layers, layers 8 and A of Potter. The tectum projects to the ipsilateral nucleus isthmi and there is a reciprocal topographic relationship between the two structures. Thus, a retino‐tecto‐isthmio‐tectal route exists which may contribute to the indirect ipsilateral retinotectal projection which is observed electrophysiologically. The connections between the nucleus isthmi and the tectum in the frog are strikingly similar to the connections between the parabigeminal nucleus and the superior colliculus of mammals.
Retinal ganglion cells in the crucian carp (Carassius carassius). I. Size and number of somata in eyes of different size
Authors: Kock Jan‐Henrik , Reuter Tom 
Published: December 2004

AbstractGanglion cell somata were drawn, measured and counted in flatmounted crucian carp and goldfish retinas stained with cresyl violet or methylene blue. Soma diameter histograms suggest that the ganglion cells can be divided into two populations with overlapping soma sizes: a large group of small cells and a small group of large cells, the latter constituting 2.5–5% of all ganglion cells. With increasing distance from the optic disc the mean soma diameter increases while the ganglion cell density decreases. In a peripheral growth zone close to the margin the ganglion cells become smaller again.The total number of ganglion cells in retinas of different size was calculated from the areas of the flat‐mounted preparations and the cell densities in two representative regions. In the crucian carp population used in this work the total number of ganglion cells per retina was found to increase from roughly 140,000 (mean of 8 scattered values) to a full 200,000 between eye diameters 4 and 10 mm, this increase taking place mainly between eye diameters of 4 and 6.5 mm.Thus, due to a drastically decreasing cell density, the total number of ganglion cells increases only by a factor of about 1.5 while the retinal area becomes sixfold. During the same growth period the mean soma diameter increases by a factor of about 1.3 and the soma volume more than doubles. The optic nerve of a small crucian carp was studied by electron microscopy. About equal numbers of unmyelinated and myelinated axons were found. The axons in the optic nerve are, on an average, considerably thicker than the axons on the retinal surface.
Embryonic behavior, hatching and neuromuscular development in the chick following a transient reduction of spontaneous motility and sensory input by neuromuscular blocking agents
Authors: Oppenheim Ronald W. , Pittman Randall , Gray Marjory , Maderdrut Jerome L. 
Published: December 2004

AbstractEmbryos were immobilized with neuromuscular blocking agents for one to four days between days 10 and 15 of incubation. This treatment reduces spontaneous motility, as well as movement‐initiated proprioceptive and cutaneous stimulation. Although the major aim of these experiments was to determine the effects of such treatment on subsequent behavioral development, several indices of neuromuscular and general morphological development were also examined.A single injection of curare on day 10 continues to depress spontaneous motility for virtually the entire remaining incubation period. This effect is due to the persistence of unmetabolized curare in the closed system of the egg. When a comparable dose of a rapidly metabolized neuromuscular blocking agent (succinylcholine) is given, this long term behavioral depression is not found. Embryos treated with SC can remain totally immobilized for up to 60 hours with no apparent repercussions on subsequent behavior; spontaneous embryonic motility, reflex sensitivity, hatching, and several general posthatching behaviors, all appeared normal following such treatment.Embryos immobilized for as little as 48 hours developed joint malformations and were retarded in general growth by about one day whereas 24 hours of paralysis was not sufficient to induce these effects.Twenty‐four hours of total paralysis from days 10 to 11, plus a 40–50% reduction in motility until days 15 or 16, does not appear to cause any abnormalities in muscle or spinal cord development. Muscle histology, motor endplates, cell number in the spinal cord and choline acetyltransferase and acetylcholinesterase activity in spinal cord and muscle were all comparable to controls. An 80–90% reduction in motility on days 11 through 15, however, induces an apparent alteration of the intensity and distribution of histochemically demonstrable AChE in the anterior and posterior latissimus dorsi muscles.The present findings suggest that the suppression of overt motility for a period comprising ca. 5–12% of the total incubation time (21 days) does not modify subsequent behavioral development or the underlying neurogenetic mechanisms. Though these findings provide some support for the notion that the embryonic nervous system develops in forward reference to and without benefit from function or sensory input, only a more complete reduction of neural function, especially CNS activity, can provide a critical test of this concept.
The developmental morphology of Torpedo marmorata: Electric organ — Myogenic phase
Authors: Fox Geoffrey Q. , Richardson Guy P. 
Published: December 2004

AbstractThe early development of the electric organ of Torpedo marmorata has been examined by light and electron microscopy to the 40‐mm stage of embryo growth. The myogenic nature of this tissue is confirmed ultrastructurally by the presence of myoblasts and myotubes both containing myofibrils cross striated with Z, A and I bands. Fusion between these cells is also found taking place. A scheme is presented to explain the development of the overall structural plan of the organ and specifically the formation of the future electrocyte columns.At 40 mm, a series of morphological transformations signals the onset of a divergent developmental pattern ultimately leading to the establishment of mature electrocyte columns. These features include rounding up of myotubes, dissolution of myofibrils and the appearance of intermediate size filaments (11 nm) and perhaps a non‐muscular actin (5.5 nm). This early myogenic phase of development occurs in the absence of any specific nervous contact even though electromotor nerves are always in close proximity.
Photoreceptors and oil droplet colors in the red area of the pigeon retina
Authors: Mariani Andrew P. , Leure‐Dupree Alphonse E. 
Published: December 2004

AbstractSix types of photoreceptors in the red area (dorso‐temporal quadrant) of the pigeon retina are identified using Golgi impregnation, light microscopy and electron microscopy. Golgi impregnation is used to categorize the receptors into morphological types. Examination of oil droplets in the inner segments of cones in fresh, unfixed tissue shows five different types which can be characterized by color, size and stratification. Therefore, in sections through the length of the receptors examined by electron microscopy, the oil droplets contained in the inner segments of the cones can be identified as to their color by their characteristics (i.e., size and stratification), and the groups of receptors thus classified, further characterized as to the morphology of their terminals. Rods have no oil droplets in their inner segments, and their synaptic terminals are located in the outermost stratum of the outer plexiform layer (OPL). Principal members of double cones have yellow oil droplets in their inner segments, while accessory members contain small colorless oil droplets. The synaptic terminals of double cones are located in the same (outermost) stratum of the OPL as rod synaptic terminals. Two types of single, straight cones house either red or orange oil droplets and terminate in the intermediate stratum of the OPL. Oblique single cones with yellow‐green oil droplets in their inner segments contribute synaptic terminals to the innermost stratum of the OPL.
A golgi study of cell types in the hilar region of the hippocampus in the rat
Authors: Amaral David G. 
Published: December 2004

AbstractThe morphology of neurons in the “hilar region” of the hippocampus (fields CA3c and CA4 of Lorente de Nó, '34) was analyzed with several variants of the Golgi technique. Hippocampi were dissected from the brains of 28‐day‐old rats, fixed and impregnated by immersion, and sectioned perpendicular to the long axis. Based on the resident cell types, aspects of the neuropil, and published data related to afferent termination, the area under study was divided into four zones. At least 21 cell types were observed throughout these zones, several of which had not previously been described. Many cells in this area exhibited an impressive number and variety of dendritic and axonal appendages, including spines on the proximal portion of some axons. The close apposition of fibers to these axonal spines suggested the possibility of axo‐axonal interactions. The influence of dentate granule cells, through their mossy fibers, on the synaptic economy of the “hilar region” was found to be more extensive than previously reported. Mossy fibers appeared to terminate on the dendrites of several types of non‐pyramidal cells, which bear no thorny excrescences, by means of thin filiform extensions which emanate from the mossy fiber expansions and by means of thin mossy fiber collaterals which are devoid of typical expansions. Consideration is given to a long‐standing debate as to whether the deep “hilar region” (CA4 of Lorente de Nó, '34, hilus of the fascia dentata of Blackstad, '56) is related more to the hippocampus or to the fascia dentata and it is concluded that the deep hilar region is an area of mergence of the polymorphic zones of these two cortical structures. The results of the present study do not support the proposition that the deep hilar region is an extension of the pyramidal layer of the hippocampus as suggested by Lorente de Nó ('34), and thus CA4 is a misnomer. Rather, the cells in this area are most closely related to the fascia dentata and should thus be considered to lie in the polymorphic zone of “area dentata” as proposed initially by Blackstad ('56).
The morphology of the hippocampus and dentate gyrus in normal and reeler mice
Authors: Stanfield Brent B. , Cowan W. Maxwell 
Published: December 2004

AbstractThe morphology of the hippocampus and dentate gyrus in normal and reeler mice has been studied in Nissl, myelin, Golgi, Timm's sulfide silver and gold chloride‐sublimate preparations. It is evident form both cell‐and fiber‐stained sections that despite the obvious defect in the positioning of the hippocampal pyramidal and dentate granule cells in the reeler mouse with in the radial dimension, the hippocampal formation as a whole shows a normal and consistent progression of cytoarchitectonic fields along its transverse axis, and a normal and consistent progression of changes in the structure of the hippocampus and dentate gyrus along their longitudinal axes. Thus, at least in these structures, the reeler gene seems to exert its effect only in the radial dimension.Cell counts in the area dentata indicate that the number of dentate granule cells in the reeler mouse is reduced compared to that found in normal or heterozygous animals. Although it has been known for some time that the number of granule cells in the reeler cerebellar cortex is markedly reduced, this appears to be the first evidence of a reduction in cell number in a forebrain structure.All the major cell types normally found in the hippocampus and the dentate gyrus are recognizable in Golgi‐stained preparations from the brains of reeler mutants. However, in both regions there are a number of abnormalities in the appearance of the cells which seem to be related to the cellular ectopia. Thus, whereas most of the pyramidal and granule cells which attain a normal position in the mutant usually have normal, or near‐normal dendritic arbors, the dendrites of nearly all ectopic cells are severely distorted, both in their orientation and general configuration. In preparations stained by the Timm's sulfide silver technique it is evident that the general lamination pattern seen in normal mice is retained in the reeler hippocampus and dentate gyrus despite the gross malpositioning of many of the relevant neurons. However, although the overall laminar arrangement is preserved, there are some fairly consistent abnormalities; for example, the normal trilaminar staining pattern seen in the stratum moleculare of the dentate gyrus is replaced in the reeler by a bilaminar pattern.In gold chloride‐sublimate impregnated preparations there is no obvious alignment of the astrocytes in the stratum moleculare of the dentate gyrus in either normal or reeler mice. Moreover, the distribution of the astrocytes with in this zone is fairly normal in the reeler mouse, although, in general, these cells appear to be more consistently stellate in form than in normal animals.