bluuebunny/crossref_metadata_2025_split huggingface dataset:
Projections of individual axons in lamprey spinal cord determined by tracings through serial sections
Authors: Rovainen C. M. , Johnson Patricia A. , Roach Eileen A. , Mankovsky J. A. 
Published: January 2005

AbstractThe brain and spinal cord of one adult sea lamprey, Petromyzon marinus, 12 cm in length, were fixed in glutaraldehyde and osmium, stained in toluidine blue, embedded in Araldite, and sectioned serially at 5 μ. Over 50 large axons were traced through the spinal cord to their probable cells of origin.The axon of one giant interneuron was followed from the posterior spinal cord rostrally into the lateral medulla of the brain.A formerly unrecognized pair of Müller axons was found to originate from the reticular cells I2.An unusual feature of some Müller axons was their migration out of the ventral columns and their subsequent branching.
Autoradiographic studies of the commissural and ipsilateral association connections of the hippocampus and dentate gyrus. I. The commissural connections
Authors: Gottlieb D. I. , Cowan W. M. 
Published: January 2005

AbstractThe commissural connections of the two major cytoarchitectonic fields of the hippocampus (fields CA1 and CA3) and of the dentate gyrus of the rat have been studied autoradiographically following injections of 3H‐leucine into the contralateral hippocampal formation.The commissural projection to the dentate gyrus has its origin in the hilar region of the gyrus of the opposite side (probably from the pyramidal cells of subfield CA3c) and the majority of its fibers terminate upon a restricted segment of the granule cell dendrites (about 30 μ wide) in the inner one‐third of the molecular layer. Like the ipsilateral association pathway to this region, the commissural projection has an extensive distribution along the septo‐temporal axis of the gyrus. The commissural connections of field CA3 appear to be organized homotopically in the sense that each of its subfields seems to be related principally (if not exclusively) to the corresponding subfield on the opposite side. However, along the septo‐temporal axis of the hippocampal formation the commissural projection seems to be much more widespread, so that isotope injections into this field at any one level always give rise to transported label over a considerable rostro‐caudal extent on the opposite side. Within field CA3 the commissural terminals are confined to the region of the basal dendrites in the stratum oriens, and the middle portion of the apical dendrites in the stratum radiatum. Field CA1 does not appear to contribute to the commissural system: this is certainly true of its anterior portion which projects into the dorsal fornix rather than the fimbria, and may also hold for the posterior part of the field. Most, if not all, of the commissural fibers to field CA1 have their origin in field CA3 of the opposite side. After crossing the midline in the ventral hippocampal commissure, these fibers follow an intrahippocampal course which appears to parallel that of the Schaffer collateral system. Within field CA1 the crossed fibers terminate in relation to the basal dendrites and the proximal three‐fourths of the apical dendrites in the stratum oriens and the stratum radiatum.
Quantitative studies of transneuronal atrophy in the dorsal lateral geniculate nucleus of cats and kittens
Authors: Guillery R. W. 
Published: January 2005

AbstractThe transneuronal cell atrophy that occurs in the dorsal lateral geniculate nucleus after removal of one eye is more rapid in young than in adult cats. The change in the rate of the atrophic change continues well beyond the time at which geniculate cell growth has stopped.In a three and a half month old kitten transneuronal cell shrinkage is clearly evident within three days on the side contralateral to an enucleation, but it does not appear clearly on the ipsilateral side until the twelfth post‐operative day. On both sides of the brain there is some apparent recovery and then a later, slower cell shrinkage. In a seven month old cat the cell changes are slower, and the two stages of the atrophy are less clearly distinguishable.In the three and a half month kittens there is no significant differences between the atrophy that occurs in the binocular and the monocular parts of the nucleus and it is concluded that a binocular, or translaminar competition plays no part in producing the atrophic changes in these kittens. However, in a seven day old kitten removal of one eye appears to produce more severe atrophy in the binocular than in the monocular parts of the nucleus. Thus, a binocular competition, similar to that seen after a lid suture in seven day old kittens, may play a part in the transneuronal atrophy in these very young animals but not in older kittens.
The sensura neglecta in the pigeon: A scanning electron and light microscope study
Authors: Correia Manning J. , Landolt Jack P. , Young Eric R. 
Published: January 2005

AbstractBoth scanning electron and light microscopy have been used to observe the tiny sensura neglecta which is located in the inferior utricular sinus of the vestibular labyrinth in the pigeon. The following new observations were made. The end organ, which occupies one‐third of the floor of the inferior utricular sinus, is ovoid, measuring 200 μm in length × 80 μm in width and 30 μm in height. The neuroepithelium of the neglecta is uniformly innervated by the neglectar nerve which contains about 60 to 90 myelinated nerve fibers that fasciculate from the posterior ampullary nerve. The fiber spectrum is unimodal with a mode diameter of 1–2 μm. From 150 to 200 Type I and Type II hair cells are found on the surface of the neglecta. The surface features of the hair cells, i.e., the pipe organ patterns of the stereocilia are identical to that of the other vestibular sensory regions. No hair cells are found on the sides of the neglecta and all hair cells project their tufts upward from the top surface. The sensory region of the neglecta is covered by a gelatinous membrane. In no instance are statoconia observed on this covering. The non‐sensory epithelium contiguous to the sensura neglecta is comprised only of “light cells” (Dohlman, '67).The above observations indicate that the sensura neglecta in the pigeon has both crista‐ and macula‐like features. It is hypothesized that this is reasonable from an evolutionary and teleological point of view. It is further suggested that regardless of its similarities to the statolithic and canalicular organs, the mode of stimulation of the neglecta can best be described by analogy to the culmen type of system associated with the auditory papilla of the lizard (Wever, '71).
A radioautographic study of the efferent pathways of the nucleus locus coeruleus
Authors: Pickel Virginia M. , Segal Menahem , Bloom Floyd E. 
Published: January 2005

AbstractThe projections of neurons in the nucleus locus coeruleus (LC) of the rat were traced by radioautography following stereotaxic injections of 3H‐proline. An ascending bundle consisting of a dense cluster of labeled axons accompanied the medial forebrain bundle (MFB) into the lateral hypothalamus. Rostral to the anterior commissure, the labeled fibers contributed to other major pathways: the stria terminalis to the amygdala, and the cingulum bundle and the supracallosal stria to the cingulate cortex, subiculum, and hippocampus. The rest of the ascending fibers terminated diffusely in the pyriform cortex and frontal neocortex. In addition, a lateral group of labeled fibers entered the cerebellum through the superior cerebellar peduncle and terminated around the Purkinje cell somata and in the molecular layer. Descending fibers which entered the medulla either terminated around brainstem nuclei or passed into the ventral portion of the spinal cord. In all areas except the brainstem, the labeling was unilateral with respect to the injection site. This distribution of label from LC provides direct confirmation for connections which have been difficult to visualize in their entirety by any other histological or cytochemical method.
Axonal proliferation following lesions of cerebellar peduncles. A combined fluorescence microscopic and radioautographic study
Authors: Pickel Virginia M. , Segal Menahem , Bloom Floyd E. 
Published: January 2005

AbstractThe hippocampus and the cerebellar cortex, two terminal fields of N. locus coeruleus (LC), contain increased adrenergic innervation 30 days after partial lesions of the superior cerebellar peduncle (SP). The qualitative observation of enhanced terminal fluorescence after lesioning was confirmed by counting terminals in the hippocampus and cerebellum labeled by radioautography after injection of 3H‐proline into LC of the rat. Use of the Vibratome method for catecholamine‐fluorescence permitted the observation of both fluorescence and labeled terminals in sections from the same animal. The increased terminal density in the hippocampus following partial SP lesions suggests that this growth may be initiated by retrograde changes within LC neurons or collaterals of the cut axons and does not require a prior denervation of the post synaptic cells.
Differences in membrane structure between excitatory and inhibitory components of the reciprocal synapse in the olfactory bulb
Authors: Landis Dennis M. D. , Reese T. S. , Raviola Elio 
Published: January 2005

AbstractThe reciprocal dendro‐dendritic synapse between granule and mitral or tufted dendrites in the external plexiform layer of the olfactory bulb consists of an excitatory mitral‐to‐granule synaptic contact and an adjacent inhibitory granule‐to‐mitral synaptic contact. The pre‐ and postsynaptic membranes of both synaptic contacts were identified in replicas of freeze‐fractured external plexiform layer in rabbits, mice, and chinchillas. At the excitatory synaptic contact there is a prominent specialization in the postsynaptic memberane, represented by an aggregate of homogeneous particles associated with the external half of the membrane. In contrast, the postsynaptic membrane at the inhibitory granule‐to‐mitral synaptic contact lacks evident internal specializations, and the distribution of particles on both fracture faces resembles that at non‐synaptic regions. Less marked differences in particle distribution characterized the cytoplasmic half of the presynaptic membranes. These differences probably reflect diversity in the nature or distribution of membrane proteins at excitatory and inhibitory synapses. Protuberances on the external half of the presynaptic membrane, possibly sites of vesicle interaction with the plasma membrane, surrounded but were not coextensive with both types of synaptic contact. A few gap junctions connected proximal dendrites of mitral or tufted cells with granule cell dendrites.
The specification of the retino‐tectal projection in the chick
Authors: Crossland W. J. , Cowan W. M. , Rogers Lynn A. , Kelly James P. 
Published: January 2005

AbstractThe specificity of the connections between the retina and the optic tectum has been studied in the chick by ablating between 15% and 75% of the optic cup (usually during the third day of incubation) and subsequently determining the distribution, within the tectum, of the synapses formed by the axons of the surviving ganglion cells. This was done towards the end of the incubation period, or shortly after hatching, either autoradiographically following the injection of a tritiated amino acid into the eye, or using a variant of the Nauta‐Gygax method after sectioning the optic nerve. In every case in which the initial retinal lesion was placed after Stage 12/13 (i.e., late on the second day of incubation) the surviving ganglion cells could be shown to have formed synapses in only a limited region of the contralateral optic tectum; and as far as could be determined from an examination of the cell loss in the isthmo‐optic nucleus (in which the centrifugal fibers to the retina have their origin) the remaining portion of the neural retina consistently projected only to the homotopic region of the tectum (i.e., the region to which it would normally have been expected to project). In several cases it was found that the axons had passed over a heterotopic region of the tectum in order to reach a more distant region in which they had formed synapses. After a lesion of the optic vesicle before Stage 11 the surviving ganglion cells appeared to innervate all parts of the tectum; since the earliest retinal ganglion cells are formed at Stage 11/12 it would seem that in the chick, as in Xenopus, there is a clear temporal co‐incidence between the withdrawal of the first ganglion cells from the cell‐cycle and the establishment of the topographic specification of the retino‐tectal projection.Preliminary studies of the projection of the retina upon the optic tectum, and of the tectum upon the isthmo‐optic nucleus, in four to five week old chicks, indicates that the organization of these connections (and hence, presumably, that of the centrifugal fibers from the isthmo‐optic nucleus to the retina) is essentially the same as that in the pigeon. However, there is a significant difference in the overall morphology of the isthmo‐optic nucleus in the two species: as can best be seen in parasagittal sections, the isthmo‐optic nucleus of the chick lacks a well‐developed “anterior limb,” so that the representation of the horizontal meridian lies close to the junction of the “body” of the nucleus and its “posterior limb”.
Cell survival and architectonic differentiation of the hypothalamic mamillary region of the newborn mouse in culture,
Authors: Sobkowicz Hanna M. , Bleier Ruth , Monzain Rachel 
Published: January 2005

AbstractThe development of the hypothalamic mamillary region of the newborn mouse has been studied in 519 cultures. The nuclear groups of the mamillary configuration as well as the infundibular nucleus may survive for at least 50 days. The surviving neuronal groups undergo in culture a further cytological and structural organization. The presence of ependymal tissue at the surface of the substrate enhances ependymal‐glial proliferation and this in turn supports the survival and new growth of the nerve cells in the adjacent areas. On the other hand, degeneration of white matter, especially if it occurs between the substrate and the overlying neuronal groups, has a highly detrimental effect leading to a profound regional neuronal loss. The survival of neuronal groups, the new axonal growth and the preservation of the cellular architectonics, which make possible their identification in culture, indicate that the mamillary complex has a capacity for regeneration during its development in isolation. The mamillary region and the infundibular nucleus display different developmental patterns and different structural organizations of their cells and axons. As a result, the culture seems to be divided morphologically into two distinctly separate regions.
The distribution of the sensory input in the dorsal spinal cord of the tortoise
Authors: Rosenberg M. E. 
Published: January 2005

AbstractThe functional distribution of dorsal horn structures in the lumbo‐sacral spinal cord of the tortoise (T. graeca, T. hermanni) was determined by surface mapping of the cord dorsum potential in the decerebrate animal. Electrical stimuli were applied to either skin, peripheral nerve, dorsal roots or dorsal tracts. It was shown that the cord dorsum potential in this reptile could be interpreted in the same way as that in the mammal; this permitted identification of the primary volley separately from the consequent activity of post‐synaptic structures within the dorsal horn. The longitudinal distribution of post‐synaptic activity suggested that the associated structures are not distributed uniformly along the cord but rather have concentration maxima within segments in regions just rostral to the root entry zones. Combined transverse and longitudinal mapping revealed streaming of postsynaptic activity, traced over two or three segments, towards the mid line, when proceeding rostrally from a given root entry zone. The fact that this occurred for successive roots suggests that somatotopic representation exists in the transverse plane within the dorsal horn.The longitudinal distribution of post‐synaptic activity suggested that the associated structures are not distributed uniformly along the cord but rather have concentration maxima within segments in regions just rostral to the root entry zones.Combined transverse and longitudinal mapping revealed streaming of post‐synaptic activity, traced over two or three segments, towards the mid line, when proceeding rostrally from a given root entry zone. The fact that this occurred for successive roots suggests that somatotopic representation exists in the transverse plane within the dorsal horn.
An autoradiographic study of the efferent connections of the ventral lateral geniculate nucleus in the albino rat and the cat
Authors: Swanson L. W. , Cowan W. M. , Jones E. G. 
Published: January 2005

AbstractThe efferent connections of the ventral lateral geniculate nucleus (LGNv) of the albino rat and the cat have been studied using the autoradiographic method for tracing axonal pathways. Following the injection of 3H‐proline or 3H‐leucine into the LGNv of the rat, label transported in the rapid phase of axonal flow was found bilaterally in the olivary pretectal nuclei, the lateral terminal nuclei of the accessory optic system, and the ventral portion of the suprachiasmatic nuclei of the hypothalamus, and ipsilaterally in the rostrolateral portion of the superior colliculus. Since these regions are known to receive a direct projection from the retina, comparisons have been made of the distribution of silver grains in autoradiographs of each region following injections of 3H‐proline into the eye and into the LGNv; in every nuclear region except the superior colliculus the grain distributions were found to overlap precisely and, in the suprachiasmatic nuclei there also appears to be a similarity in the relative intensity of the input to the nuclei on the two sides. In the superior colliculus, the retinal fibers end mainly within the more superficial laminae, whereas those from the LGNv are distributed mainly to the deeper layers where they overlap the projection from the striate and peristriate cortex. The LGNv has also been found to project to the zona incerta on the same side and to the contralateral LGNv, In the cat a similar set of projections to the lateral terminal nuclei of the accessory optic tract, the suprachiasmatic nuclei, and the pretectal areas of both sides has been found, together with a projection to the ipsilateral superior colliculus and the zona incerta of both sides. No evidence could be found in either species for a projection from the LGNv to the visual cortex.
Topological analysis of the brain stem: A general introduction
Authors: Nieuwenhuys Rudolf 
Published: January 2005

AbstractThis paper introduces a research project within the framework of which the brain stems of twelve representative vertebrates will be analysed according to a new procedure termed topological analysis. The first part reviews the development of the concept that the brain stem essentially consists of a number of longitudinal zones or columns. From this review it appears that, although during the past 80 years a considerable amount of evidence favoring this concept has been accumulated, a number of important questions pertaining to number, delimitation and content of the zones in the brain stem are still awaiting a definitive answer. The second part of this paper is devoted to a detailed description and a critical evaluation of the topological procedure. This procedure, which has been especially designed to facilitate the study of the zonal pattern of the brain stem, essentially involves two steps. First the cell masses are projected back to their site of origin at the ventricular surface, and next the ventricular surface, with its sulci and the projections of the cell masses marked upon it, is flattened out, i.e., is subjected to a one‐to‐one topological transformation. In the third part of this paper the choice of the species which will be studied within the framework of our program is discussed. The species selected are: the lamprey Lampetra fluviatilis, the shark Squalus acanthias, the actinopterygians Acipenser fulvescens, Lepisosteus osseus and Salmo irideus, the brachiopterygian Polypterus ornatipinnis, the lungfish Lepidosiren paradoxa, the crossopterygian Latimeria chalumnae, the amphibians Ambystoma mexicanum and Rana esculenta, the turtle Testudo hermanni, and the opossum Didelphis virginiana. In the final part the objectives of the project are discussed. Most important among these are: (1) furnishing clear and succinct analyses of the brain stems of representatives of all groups of vertebrates, (2) specification of the fundamental plan of the brain stem, (3) facilitation of the establishment of homologies and simplification of the nomenclature and (4) presentation of a sound basis for experimental hodological work.
Catecholamine‐containing neurons of the nucleus locus coeruleus in the cat
Authors: Jones Barbara E. , Moore Robert Y. 
Published: January 2005

AbstractThe nucleus locus coeruleus of the cat brain was studied using the Falck‐Hillarp fluorescent histochemical method for the demonstration of cellular monoamines. In the cat, as in other mammals, the locus coeruleus is made up of catecholamine‐containing neurons. The cell bodies of these neurons are diffusely distributed in the dorsolateral pontine tegmentum, occupying a portion of the lateral central gray and extending laterally across the paralemniscal tegmental field to surround the brachium conjunctivum in its marginal nucleus. The neurons of the locus coeruleus are readily distinguished from others in the area in Nissl‐stained material as well as in that prepared by the Falck‐Hillarp method. No subdivisions of the nucleus are evident in either Falck‐Hillarp or Nissl stained material. The locus coeruleus nucleus appears to include those neurons previously identified as the magnocellular component of the marginal nucleus of the brachium conjunctivum and the Kölliker‐Fuse nucleus.
Postembryonic growth of the optic lobe of Octopus vulgaris, lam
Authors: Giuditta Antonio , Prozzo Nicola 
Published: January 2005

AbstractThe pattern of growth of the optic lobe of Octopus vulgaris has been investigated from 0.1 to 6.0 gms body weight by measuring the weight of the lobe and the number of nuclei present in the tissue homogenate. In the normal habitat, the rate of increase in nulcear number relative to increase in body weight is 1.32 up to 1.5–1.8 gms, but undergoes a three‐fold decrease above this size. On the other hand, the rate of increase in tissue weight remains essetially constant throughout the same period of development, with the exception of the interval between 1.0 g and 1.5 gms during which it rises markedly. Nuclear density increases steadily up to approximately 1.2 gms and approaches a constant value above this size.In octopuses reared in transparent containers or under an opaque cover the rates of increment in number of nuclei and in tissue weight are generally lower than normal between 0.2 g and 1.5 gms. In both experimental conditions the wave of acceleration in the rate of increase of tissue weight occurring between 1.0 g and 1.5 gms in normal animals appears earlier particularly in octopuses reared under an opaque cover. At body weights larger than 1.5–2.0 gms the rates of increment in number of nuclei and tissue weight become higher than normal in octopuses reared in transparent boxes, but change in the opposite direction when rearing takes place in opaque containers. In the former condition, the nuclear density of newly added tissue starts decreasing earlier than normal but reaches a higher level at body weights above 2 gms, while in octopuses reared under an opaque cover the decrease occurs at approximately normal timing but attains lower values at higher body weights.