bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of cochlear innervation patterns in cats and rats with the Golgi method and Nomarski optics
Authors: Perkins R. E. , Morest D. K. 
Published: May 2005

AbstractCochlear innervation patterns were studied in infant cats and rats with the rapid Golgi method. Examination of thick serial sections and surface preparations with the differential interference contrast microscope (Nomarski optics) allowed direct visualization of individually impregnated spiral ganglion cells, complete with their peripheral processes and endings in the organ of Corti. Individually impregnated efferent fibers could be recognized as heavily varicose axons that project radially to endings beneath inner and outer hair cells after taking a tangential course in the intraganglionic spiral bundle. It was often possible to visualize unimpregnated hair cells in contact with the impregnated endings of both types of fibers. There are at least two types of spiral ganglion cells in the cochlea of the infant cat and rat. One type innervates only inner hair cells by means of radial fibers. These ganglion cells constitute the overwhelming majority of ganglion cells impregnated in our preparations, and each cell typically innervates two inner hair cells. Hence, these ganglion cells establish nearly “point‐to‐point” connections between the auditory nerve and the organ of Corti. The other type of ganglion cell innervates outer hair cells by means of long spiral fibers; each cell typically innervates many outer hair cells through the numerous angular enlargements and short end branches of its spiral fiber. In addition, a few of these spiral fibers also send branches to inner hair cells by means of short collaterals; it remains to be seen if such fibers also occur in mature cochleas. Efferent fibers have been traced to inner and outer hair cell regions. The simplest pattern is formed by fine beaded axons with only a few branches ending mainly beneath inner hair cells. More complex patterns are formed by larger axons with many branches ending beneath inner or outer hair cells. Many efferent fibers send branches to both inner and outer hair cells. Electrophysiological studies so far have not demonstrated different populations of units that clearly correspond to the spiral and radial fibers. Therefore, the physiological differences between inner and outer hair cell innervation remain undefined.
A cytoarchitectonic analysis of the spinal cord of the pigeon (Columba livia)
Authors: Leonard Robert B. , Cohen David H. 
Published: May 2005

AbstractThe spinal gray of the pigeon is described cytoarchitectonically to establish a foundation for anatomical and physiological studies of the pigeon spinal cord. The material includes segments from the high cervical cord through the lumbosacral enlargement, and nine cellular layers are described. In addition to this laminar organization, various distinct cell groups such as the dorsal magnocellular column, column of Terni, marginal cells and lobes of Lachi are described.Layers I–IV occupy the head of the dorsal horn, are apparent at all spinal levels examined, and represent the clearest case of laminar organization of the spinal gray of the pigeon. Layer V occupies the full extent of the neck of the dorsal horn at all segmental levels investigated. Also, the dorsal magnocellular column is situated in the central region of this layer from the rostral pole of the cervical enlargement through the lumbosacral enlargement, and arguments are advanced that this cell column is homologous to the column of Clarke. In the intermediate zone a Layer VI is defined, but it is apparent only at the enlargements. Layers VII–IX constitute the ventral horn, Layer IX being the motoneuronal cell groups. With the exception of the motoneuronal groups, the boundaries of the ventral horn layers are considerably less distinct than those of the dorsal horn, and no attempt is made to distinguish Layers VII and VIII at lumbosacral levels. At the enlargements there is a prominent lateral motoneuronal cell group consisting of large cells.It is generally concluded that the cytoarchitectonic organization of the spinal gray of the pigeon bears a rather close resemblance to that described for various mammalian species, particularly with respect to the dorsal horn.
The receptor mosaic of Aotes trivirgatus: Distribution of rods and cones
Authors: Ogden Thomas E. 
Published: May 2005

AbstractThe distribution and density of rods and cones have been determined in the temporal retina of the owl monkey Aotes trivirgatus. Rod density varied from 175,000/mm2 in the far periphery to 387,000/mm2 in the area centralis. Cone density was 4000/mm2 in the periphery and 7300/mm2 within the central retinal area. Variation of densities across the retina was continuous but the ratio of rods to cones remained about 50:1 at all locations. The cones are not randomly scattered, but are separated by distances of about 10 μ in central retina and 13 μ in peripheral retina.
The distribution of catecholamines within the inferior olivary complex of the cat and rhesus monkey
Authors: Sladek John R. , Bowman James P. 
Published: May 2005

AbstractCatecholamine histofluorescence was examined in the inferior olivary complex of the cat and rhesus monkey. Species‐specific patterns of catecholamine‐containing varicosities were observed. In the rat, the highest concentration of catecholamine varicosities was seen within the dorsal lamella of the principal nucleus. In contrast, this same portion of the inferior olivary complex appeared void of catecholamine varicosities in the cat and rhesus monkey. In the cat, the highest concentration of varicosities occurred within the medial one‐half of the dorsal accessory nucleus while few, if any, varicosities were seen in this portion of the complex in the rat and monkey. The lateral lamella of the principal nucleus contained the highest concentration seen in the rhesus monkey, a finding which contrasts to the minimal number of varicosities seen in this area in the rat and cat. Catecholamine‐containing cell bodies, reported to exist in the rat, were not observed in cat and monkey. These data extend the previous observation of species‐specific distribution in rodents to include members of the more phylogenetically advanced orders; Carnivora and Primata. Catecholamines were found primarily within those portions of the olivary complex reported to be involved in harmaline‐induced tremor activity in the cat.
Some cortical projections of the dorsomedial visual area (DM) of association cortex in the owl monkey, Aotus trivirgatus
Authors: Wagor E. , Lin C. S. , Kaas J. H. 
Published: May 2005

AbstractEfferent projections from the dorsomedial visual area (DM) in the owl monkey to other portions of visually responsive cortex were determined by degeneration and autoradiographic methods of demonstrating axon pathways. The most prominent ipsilateral pathway was to posterior parietal cortex (PP) just medial to the terminal portion of the Sylvian fissure. Other ipsilateral projections were to subdivisions of the temporal lobe, the middle temporal visual area (MT) and the surrounding dorsolateral crescent (DL), to regions just rostral to area 18 on the medial wall of the cerebral hemisphere, and to the upper bank of the Sylvian fissure. The callosal projections of DM were to DM, PP, and MT of the opposite cerebral hemisphere. The results support the notion that visual association cortex consists of a number of separate, but complexly interrelated, subdivisions. The efferents to posterior parietal cortex suggest the possibility of an area for the integration of somatosensory and visual information.
Retrograde changes in the nerve fibers of the dorsal spinocerebellar and spinocervical tracts in the cat
Authors: Loewy Arthur D. 
Published: May 2005

AbstractThe potential retrograde changes that occur in the proximal segment of transected nerve fibers found in the region of the spinocervical tract (SCT) and in the region of the dorsal spinocerebellar tract (DSCT) after unilateral dorsolateral column (DLC) lesions were studied in kittens and adult cats. Nerve fibers in the region of the SCT and DSCT in the spinal segments caudal to the lesion were studied in transverse sections of Epon embedded material that had been fixed by vascular perfusion with a 4% buffered paraformaldehyde solution, post‐fixed in osmium tetroxide, and stained with Azur II‐methylene blue.T8 level DLC lesions in the 10‐week old kitten resulted in a 14 to 25% decrease in mean fiber diameter in the SCT fibers (≥ 5 μ) of the T13 level. Retrograde fiber degeneration occurred in the small and large caliber fibers of the DSCT. A 15 to 30% decrease in mean fiber diameter occurred in the DSCT fibers (≥ 5 μ). The fiber density of the DSCT decreased by 20 to 30% and this could be correlated with a 20% loss of class C neurons (Loewy, '70) and a severe atrophy affecting the remaining 80% of the surviving class C neurons in the L3 segment.Mid‐cervical DLC lesions in the 10‐week old kitten resulted in a 10% decrease in mean fiber diameter in the SCT fibers (≥ 5 μ), a 15% decrease in mean fiber diameter in the DSCT fibers (≥ 5 μ), and no change in fiber density could be determined despite the finding that these lesions produced about a 10% loss of class C neurons.A T1 level lesion in a 20‐week old kitten produced no change in the SCT fibers suggesting that the changes seen in the 10‐week old kitten after midcervical lesions were probably age‐dependent changes. A 20% decrease in mean fiber diameter (≥ 5 μ) and a 6% decrease in fiber density was detected in the DSCT.T13‐L1 level DLC lesions in the adult cats resulted in degeneration of some of the large and medium size fibers in the DSCT which was most noticeable at 20 to 25 days after surgery. DLC lesions did not cause degenerative changes in the SCT fibers 5 to 25 days after surgery.
Proliferation gradients in the inner ear of the monkey (Macaca mulatta) embryo
Authors: Wilson Doris B. , Sawyer Roger H. , Hendrickx Andrew G. 
Published: May 2005

AbstractRadioautographic studies were conducted on early developmental stages of the inner ear in monkey (Macaca mulatta) embryos ranging in age from stage 11 to stage 20 (25 to 39 days' gestation) and labeled for one hour with [3H] thymidine. The most active period of proliferation occurred at stage 13, at which time all regions of the otocyst, including the endolymphatic duct, were heavily labeled. In subsequent stages the dorsal portion of the endolymphatic duct failed to incorporate label, whereas proliferation continued in the ventral portion of the duct near its communication with the medial wall of the otocyst. The duct thus appeared to grow upward as a result of cell division from below. Mitotic activity continued in the remainder of the otocyst although there was a progressive temporal decrease in the labeling index. Spatial gradients also occurred, with dorsal and lateral regions less active than ventral and medial ones. As the otocyst differentiated, the cells in various areas became attenuated. These flattened cells were still capable of undergoing cell division, as indicated by the presence of labeled nuclei in all regions of the utricle, saccule, semicircular ducts, and cochlear duct.
Dorsal column nuclei projections to the cerebellar cortex in cats as revealed by the use of the retrograde transport of horseradish peroxidase
Authors: Cheek M. D. , Rustioni A. , Trevino D. L. 
Published: May 2005

AbstractThe existence of a cerebellar projection from the dorsal column nuclei (gracile and cuneate nuclei, DCN) has been proposed on electrophysiological grounds but questioned when studied with neuroanatomical techniques. The retrograde transport of horseradish peroxidase (HRP) has been used for the present study and provides anatomical evidence of a DCN‐cerebellar pathway. In adult cats, 1 to 6 μl of 30% HRP were injected in pars intermedia of the anterior lobe (lobules IV–V), in paramedial lobule and in vermis of the anterior (lobules IV–V) and of the posterior lobe (lobule VII). After survival of 24 to 48 hours, all animals were perfused with a double aldehyde mixture and serial 40 μ sections through the medulla oblongata were incubated for visualization of HRP. In all cases, medullary nuclei known to project to the injected cortical regions of the cerebellum contained HRP‐positive neurons mainly ipsilateral to the injection (e.g., external cuneate nucleus) or mainly contralateral to it (e.g., inferior olivary complex).Following ipsilateral injections in either the paramedian lobule or the pars intermedia, HRP‐positive neurons in the cuneate nucleus were concentrated in its rostral portion where multipolar cells with radiating dendrites predominate. In contrast, none of the cells of the clusters region, in the caudal part of the cuneate nucleus, displayed HRP‐positive granules. In cases in which the anterior vermis was injected a few labelled cells were present in the rostral part of the gracile nucleus but not in the clusters region of this nucleus. No labelling of DCN neurons was evident after posterior vermis injection.To compare the distribution of cells contributing to the DCN‐cerebellar pathway with that of thalamic relay cells in the DCN, 0.5 to 3 μl of 30% HRP were injected in the nucleus ventralis posterolateralis of the thalamus in another series of cats. Contralateral to the thalamic injection, labelled cells were concentrated in the clusters region of the gracile and cuneate but rostrally in these nuclei they were scattered among unlabelled neurons.The preferential location in the DCN of cells which project to the cerebellum and of cells which project to the thalamus stresses the heterogeneous organization of these nuclei along the rostrocaudal axis. Further, the results indicate that regions of the DCN which have been distinguished on the basis of cytoarchitectonics (Kuypers and Tuerk, '64) and of afferents (Rustioni, '73, '74) differ also in their efferent projections.
Autoradiographic localization of hormone‐concentrating cells in the brain of an amphibian, Xenopus laevis. I. Testosterone
Authors: Kelley Darcy B. , Morrell Joan I. , Pfaff Donald W. 
Published: May 2005

AbstractAutoradiographic methods were used to investigate locations of hormone concentrating cells in the CNS of Xenopus laevis. Both male and female frog brains contained labelled cells. Four major hormone uptake sites were identified: the anterior preoptic area, the ventral infundibular nucleus, a dorsal tegmental area of the medulla and a presumptive motor nucleus of cranial nerves IX–X. The distribution of labelled cells was very similar for male and female brains. Available information on these testosterone uptake sites in anurans indicates possible roles in gonadotropin regulation and reproductive behavior.
Autoradiographic localization of hormone‐concentrating cells in the brain of an amphibian, Xenopus laevis. II. Estradiol
Authors: Morrell Joan I. , Kelley Darcy B. , Pfaff Donald W. 
Published: May 2005

AbstractAutoradiographic techniques for light microscopic examination of sex steroid retention were applied to the brains of male and female Xenopus laevis, an anuran amphibian, after 3H‐estradiol administration. Estrogen was concentrated by cells in three telencephalic areas (the ventral striatum, the ventral‐lateral septum and the amygdala), the anterior preoptic area, the ventral thalamus, the ventral infundibular nucleus, and in the torus semicircularis. The anterior preoptic area and the ventral infundibular nucleus contained the greatest number of labelled cells.The topography of estrogen‐concentrating cells was the same in male and female brains. This fact and comparisons of 3H‐estradiol with 3H‐testosterone retention in Xenopus suggest that the sex steroid itself, and not the genetic sex of Xenopus determines the pattern of uptake by cells in the brain.The distribution of hormone‐concentrating cells in Xenopus has many similarities to that found in birds and mammals. Preoptic, hypothalamic (tuberal), limbic forebrain and specific mesencephalic sites in all these forms contain labelled cells following radioactive sex steroid administration. Findings in Xenopus add to the argument for a phylogenetically stable system of hormone‐concentrating nerve cells in limbic, hypothalamic and mesencephalic structures.
Junctions in the meninges and marginal glia
Authors: Nabeshima Sachio , Reese T. S. , Landis Dennis M. D. , Brightman M. W. 
Published: May 2005

AbstractThe meninges of various mammals were prepared for examination with the electronmicroscope by thin sectioning or freeze‐fracturing. Particular attention was given to the distribution of tight junctions in order to determine the basis for the meningeal barrier between the blood circulating in dural vessels and the cerebrospinal fluid in the subarachnoid space. While some dural blood vessels are fenestrated, those in the subarachnoid space are not and their component endothelial cells are joined by an extensive system of tight junctions. An extensive and continuous system of tight junctions was also found in a layer of specialized cells at the border of the arachnoid with the dura. This arachnoid barrier layer is apparently the only basis of the meningeal barrier because often cellular layers in the dura and arachnoid lack tight junctions although they are linked by gap junctions and desmosomes. In particular, tight junctions are lacking at the border of the “subdural space” which is actually a fascial plane within the dura. Tight junctions are also lacking between astrocytes at the surface of the brain but these cells are linked by gap junctions and a new type of intercellular junction. The distribution of these junctions, as well as assemblies of intramembranous particles at the astrocytic border, raises the question whether this layer might have a role in the exchange of certain substances between the brain and cerebrospinal fluid.
Distribution and properties of commissural and other neurons in cat sensorimotor cortex
Authors: Miller Robert 
Published: May 2005

AbstractCommissural, cortico‐cortical and cortico‐caudate neurons have been investigated in the primary sensorimotor cortex of the cat, using antidromic stimulation techniques, and histological identification of recording sites. These neurons are to be found in all cortical laminae except the first; commissural and cortico‐cortical neurons were found to be commonest in laminae III and VI, whilst cortico‐caudate neurons were most abundant on the border between laminae III and V, in motor areas. In sensory areas topographically identified as representing distal parts of limbs, commissural neurons are very rare, confirming neuroanatomical studies on the origin and termination of callosal fibres.The intracerebral neuronal projections investigated in this study had slow conduction velocities (less than 1 m/sec, up to about 10 m/sec). It was found that projections from area 6, whether commissural, cortico‐caudate, or corticopeduncular have slower conduction velocities than their counterparts from area 4. It is suggested that this is related to the type of motor control in which these two areas are involved (slowly‐responding postural movements, as opposed to more rapid distal limb movements). No neurons were found which had both commissural (or cortico‐cortical), and cortico‐fugal projections.
Tectal efferents in the blind cave fish Astyanax Hubbsi
Authors: Sligar Catherine M. , Voneida Theodore J. 
Published: May 2005

AbstractSuction lesions were placed in the optic tecta of 36 blind cave fish. Three main bundles of tectal efferents were observed. A large, caudally directed fascicle distributes to the ipsilateral torus semicircularis, nucleus isthmi, and lateral tegmental areas of the mesencephalon and pons via the ipsilateral tectobulbar tract. Contralaterally, this fascicle descends to pontine levels as the contralateral tectobulbar tract.A second, rostrally directed bundle exits from the tectum at two levels. A small fascicle leaves from the caudal tectum and ascends rostrally as the commissura transversa. This bundle then joins with more rostrally exiting fibers and the combined fascicles collect in the area of the medial optic tract. They remain in this position until the level of the postoptic commissure where they decussate. Subsequently, this bundle moves caudally and enters the contralateral tectum at its most rostral extreme.The third bundle of tectofugal efferents leaves the tectum medially, at the level of the lesion, and enters the tectal commissure, through which it is distributed to the ipsilateral torus longitudinalis and contralateral optic tectum.
Early formation of synapses in the molecular layer of the fetal rat cerebellum
Authors: West Mark J. , Del Cerro Manuel 
Published: May 2005

AbstractThe initial phase of synaptogenesis in the molecular layer of the albino rat cerebellum has been studied quantitatively and qualitatively with the electron microscope. Using both aldehyde‐osmium (AL‐OS) and ethanolic phosphotungstic acid (E‐PTA) preparations, synapses were observed as early as embryonic day 19 throughout the entire rostro‐caudal extent of the vermal molecular layer. The undeveloped nature of the elements participating in the formation of these synapses precluded their identification, for at this stage of cerebellar development, the Purkinje cells have not developed characteristic dendrites and both the massive production of cells within the external granule layer and the migration of neuroblasts through the molecular layer are in their initial phases. Evidence of synapse formation at this early stage of molecular layer development indicates that the rudiments of neuronal systems are present before the bulk of the molecular layer has come into existence and before most of the constituent elements of the cerebellum have differentiated. From embryonic day 19 to embryonic day 22, the number of E‐PTA synaptic contacts was always less than the number of AL‐OS synapses. This discrepancy and the variations observed in the morphology of the presynaptic components of E‐PTA stained synaptic contacts, indicate that E‐PTA morphology, and particularly the development of presynaptic dense projections, represents a late stage of synapse formation.
The topographical distribution of S‐100 and GFA proteins in the adult rat brain: An immunohistochemical study using horseradish peroxidase‐labelled antibodies
Authors: Ludwin S. K. , Kosek J. C. , Eng L. F. 
Published: May 2005

AbstractThe cytological and topographical distribution of S‐100 and glial fibrillary acidic (GFA) proteins in the adult rat brain has been compared using the horseradish peroxidase‐labelled antibody technique. Both proteins are present in astrocytes and structures composed of astrocytic processes, namely the glial limitans and the perivascular membranes, but the cytological localization varies between the two proteins. S‐100 is found in the nucleus and cytoplasm whereas GFA protein is confined to the cytoplasm. Neither is found in neurons, but S‐100 is present in some oligodendroglia, suggesting a general regulatory role in glia. Although GFA protein is present in both protoplasmic and fibrous astrocytes, it is more prominent in the latter, confirming its association with astrocytic filaments.