bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunocytochemical localization of glutamate decarboxylase in rat spinal cord
Authors: McLaughlin Barbara J. , Barber Robert , Saito Kihachi , Roberts Eugene , Wu J. Y.
Published: May 2005

The GABA synthesizing enzyme, glutamate decarboxylase (GAD), has been localized by light and electron microscopy in the rat lumbosacral spinal cord using a peroxidase‐labeling antibody technique. The light microscopic localization shows heavy, punctate reaction product for GAD in the dorsal horn laminae I–III. Moderately heavy reaction product is also seen in the deeper dorsal horn laminae IV–VI, the medial aspect of the intermediate gray (lamina VII) and the region around the central canal (lamina X). A moderately light concentration of GAD reaction product is observed in the ventral horn, and punctate deposits of reaction product also are seen on motoneuron cell bodies.

The punctate distribution of reaction product for GAD in both ventral and dorsal horns, as visualized by light microscopy, corresponds to GAD‐containing synaptic terminals seen by electron microscopy in comparable regions of the spinal gray. Many more GAD‐positive terminals are observed in dorsal horn laminae I–III than in deeper laminae IV–VI. GAD‐containing terminals in the dorsal horn are presynaptic to dendrites and cell bodies. GAD‐containing terminals presynaptic to other axon terminals are observed also, and they are more numerous in laminae II and III. In the ventral horn motor nuclei, GAD‐positive knobs are presynaptic to large and small dendrites and motoneuron cell bodies. In addition, small GAD‐containing terminals also are presynaptic to larger axonal terminals which are in turn presynaptic to motoneuron somata.

The observation of GAD‐containing terminals presynaptic to dendrites and cell bodies in both dorsal and ventral horns is compatible with the evidence suggesting that GABA terminals may mediate postsynaptic inhibition of spinal interneurons and motoneurons. The additional finding of GAD‐positive terminals presynaptic to other axonal terminals in the dorsal horn and motor nuclei is consistent with the growing evidence that GABA also may be the transmitter mediating presynaptic inhibition via axo‐axonal synapses in the spinal cord.
Catecholamine distribution in feline hypothalamus
Authors: Cheung Yvonne , Sladek John R.
Published: May 2005

Catecholamine distribution was examined in cat hypothalamus using the histochemical fluorescence technique of Falck and Hillarp. The heaviest accumulations of catecholamine‐containing varicosities were seen within the: anterior periventricular nucleus; dorsal hypothalamic area; bed nucleus of the inferior thalamic peduncle; dorsal component of the paraventricular nucleus; dorsomedial nucleus; infundibular nucleus; bed nucleus of the stria terminalis‐medial division; and supraoptic nucleus. Catecholaminergic perikarya were observed within periventricular, dorsal, and caudal hypothalamic areas as well as within the supramamillary nucleus and caudal diencephalon. Catecholamine distribution in cat hypothalamus possesses both similarities and dissimilarities in relation to distributions reported in other mammals.
Corticoseptal projections in the snakes Natrix sipedon and Thamnophis sirtalis
Authors: Ulinski Philip S.
Published: May 2005

The projections of the cerebral cortex upon the septum in water snakes (Natrix sipedon) and garter snakes (Thamnophis sirtalis) were studied with the Fink‐Heimer degeneration techniques. Two cortical areas send major projections to the septum. Medial cortex projects bilaterally to the dorsal portion of the precommissural septum along its full rostrocaudal extent. The ipsilateral projection is more massive than the contralateral one. Dorsal cortex projects ipsilaterally to a column within the septum which is present dorsally, caudal to the level of the anterior commissure, but shifts ventrally as the septum is followed rostrally. Lateral cortex may send a sparse projection to the ipsilateral ventral septum.
Olfactory relationships of the telencephalon and diencephalon in the rabbit. II. An autoradiographic and horseradish peroxidase study of the efferent connections of the anterior olfactory nucleus
Authors: Broadwell Richard D.
Published: May 2005

The efferent connections of the anterior olfactory nucleus in the female albino rabbit have been studied using the autoradiographic and horseradish peroxidase methods for tracing axonal pathways. Following a unilateral injection of 3H‐leucine into the olfactory peduncle, radioactively labeled efferent projections from the anterior olfactory nucleus were traced into all layers of the ipsilateral main olfactory bulb beneath the olfactory nerve layer and through the ipsilateral anterior limb of the anterior commissure and plexiform layer of the medial side of the cerebral hemisphere to the deep half of the plexiform (IB) and pyramidal cell (II) layers of the prepyriform cortex, the tenia tecta, and the entire surface of the olfactory tubercle. Labeled projections crossing the midline within the anterior commissure were followed to layers IB and II of the contralateral anterior prepyriform cortex and pars externa, pars lateralis, and pars dorsalis of the anterior olfactory nucleus, and through the periventricular layer of the olfactory peduncle to all layers of the main olfactory bulb beneath the olfactory nerve layer. No well‐defined labeled projection was traced to the contralateral accessory olfactory bulb. Evidence for possible anterior olfactory nucleus and/or prepyriform cortical projections to the ipsilateral paleocortical half of the claustrum, horizontal limb of the nucleus of the diagonal band, the posterior lateral hypothalamus at the level of the mammillary complex, and to the bed nucleus of the stria terminalis is discussed. Intra‐axonal retrograde transport of horseradish peroxidase from axon terminals to parent cell bodies after unilateral injection of the protein into the main olfactory bulb or anterior olfactory nucleus revealed that anterior olfactory nucleus projections to the olfactory bulbs and the contralateral anterior olfactory nucleus arise predominately from the pars externa.

The autoradiographic data indicate that the anterior olfactory nucleus projects to olfactory cortical structures which also receive afferent input from the olfactory bulb and that the termination of these projections is complementary to those from the olfactory bulb.
A normally laminated afferent projection to an abnormally laminated cortex: Some olfactory connections in the reeler mouse
Authors: Devor Marshall , Caviness Verne S. , Derer Paul
Published: May 2005

The relative positions of pyramidal and polymorphic cell classes are inverted in the central olfactory cortical structures of the reeler mutant mouse. Each cell class is generated at the normal embryonic time. The polymorphic cells of the mutant, like those of the normal, are generated between E11–E13. The pyramidal cells are formed between E11–E16 in both. Despite the anomalous positions of their somata deep in the cortex the apical dendrites of many pyramidal cells reach and ramify at a superficial cortical level subjacent to the lateral olfactory tract. The main and accessory olfactory bulbs are cytoarchitectonically normal in the mutant and project normally upon the anterior olfactory nucleus, the olfactory tubercle, the hippocampal rudiment, the piriform cortex, the amygdaloid region and the entorhinal cortex. As in the normal animal the axons traverse layer Iα, and their terminals are concentrated in the immediately subjacent laminar zone. The rostrally directed cortico‐cortical association system of the piriform cortex projects upon the anterior olfactory nucleus in the mutant just as in the normal with a relative concentration of terminals in a lamina subjacent and complementary to the zone of termination of the lateral olfactory tract. The normal pattern of lamination of these two afferent systems in the abnormally laminated olfactory cortex of the mutant suggests that, in this system at least, the developmental mechanisms which determine relative position of neuron somata and those which govern axon trajectories and the distribution of axon terminals are largely independent.
Anatomy of the cerebral ganglion of the male Acanthocephalan, Moniliformis dubius
Authors: Dunagan T. T. , Miller Donald M.
Published: May 2005

An atlas of the cerebral ganglion of Moniliformis dubius has been constructed and the cells identified by number. There is a total of 88 cells, two of which are binucleate. These cells (20 and 90) are located in the frontal plane. The cell population is equally distributed between each half of the ganglion, there being 41 cells on each side with six cells centrally located between the two halves. Most cells give rise to bilateral processes and are organized in such a way that there is an outer coat of somata or cell bodies. Cell bodies predominate on the ventral surface, but the dorsal surface is more of a mixture of cell bodies and nerve processes. The core or neuropile occupies the central part of the ganglion and is the site for cross over for many cell processes which then exist from the side opposite the cell body. The cytoarchitecture of these cells varies considerably. Most have a large round nucleus with well defined nucleoli.
Functional localization and cortical architecture in the nine‐banded armadillo (Dasypus novemcinctus mexicanus)
Authors: Royce G. James , Martin George F. , Dom Richard M.
Published: May 2005

A functional map of the armadillo neocortex was produced by cortical stimulation and recording evoked potentials following somatic, auditory and visual stimuli. The results obtained were then correlated with the cortical architecture as revealed by Nissl, Golgi and myelin‐stained sections. Cortex rostral to the supraorbital sulcus has a wide layer IV and is mostly silent, except for a motor eye field and a part of the tongue sensory region in its caudal part. Two types of motor‐sensory cortex are present caudal to the supraorbital sulcus. Postsupraorbital I is mostly motor and has prominent pyramidal layers. Layer V is particuarly well developed and in rostral sections its superficial zone is broken up into clusters similar to the solid “barrels” seen in layer IV of other species. Postsupraorbital II has less prominent pyramidal layers and layers II and III are organized into clusters. This region corresponds to the sensory area for the limbs and trunk and the partially overlapping (surface recordings) sensory and motor areas for head, snout and tongue. Digits and limbs are rostral to the trunk representation in both the sensory and motor “homunculi.” Even though surface recording was employed, potentials evoked by visual stimuli could only be recorded from a small caudal area with a very thin layer IV. Although striate and peristriate areas appear similar in Nissl stained preparations, they can be readily differentiated in Weil stained sections. The stellate character of neurons in layer IV of the visual cortex is particularly apparent in Golgi material. Auditory evoked surface potentials were recorded from a broad oval region in the caudal lateral cortex which has a wide layer IV and aggregates of neurons in layers II and III. A Weil stain demonstrates inner and outer bands of Baillarger in this same region. The presumptive insular cortex is electrically silent to sensory stimulation and presents as a narrow band just dorsal to the rhinal fissure with indefinite cell lamination and little myelin.
Experimental reorganization of the cerebellar cortex. V. Effects of early X‐irradiation schedules that allow or prevent the acquisition of basket cells
Authors: Altman Joseph
Published: May 2005

In neonate and infant rats the area of the cerebellum was irradiated with different schedules of single or multiple doses of low‐level X‐ray. One set of schedules allowed the early recovery of the external germinal layer and the differentiation of all the postnatally‐forming cell types while the other selectively prevented the acquisition of basket cells. The first schedule did not interfere with the development of normally oriented and arborizing Purkinje cells. The second schedule led to the growth of twisted and entwined stem dendrites even when, in association with the recovered granule cells, parallel fibers were present in the molecular layer together with Purkinje cell spiny branchlets. Evidence was presented that the alignment of Purkinje cell perikarya in a monolayer does not guarantee the normal growth of Purkinje cell stem dendrites which may be dependent on the presence of basket cells. The problem was discussed whether cell differentiation in the cerebellar cortex is governed by a chronological or sequential principle.
Experimental reorganization of the cerebellar cortex. VII. Effects of late X‐irradiation schedules that interfere with cell acquisition after stellate cells are formed
Authors: Altman Joseph
Published: May 2005

In Long‐Evans rats the area of the cerebellum was irradiated with multiple doses of low‐level X‐ray beginning on day 12 after the bulk of stellate cells were acquired. The treatment spared basket, stellate and early‐forming granule cells but led to a substantial reduction in the total granule cell population and a correlated miniaturization of the cerebellar cortex. Nevertheless most Purkinje cells had normally shaped planar dendritic arbors, with an upward directed stem dendrite, several smooth branches and a multitude of spiny branchlets. The frequent piling up of spiny branchlets near the surface was attributed to the truncation of the bed of parallel fibers by this radiation schedule.

In this last paper of the series the accumulated results are summarized and evaluated. The hypothesis is offered that while the growth of the Purkinje cell perikaryon is an autonomous process, the oriented perpendicular growth of a single stem dendrite depends on the presence of basket cell axons, the outgrowth of smooth branches on the presence of stellate cell axons, and the proliferation of spiny branchlets on interaction with parallel fibers. The parallel fibers are responsible for the orthogonal, planar growth of the dendritic arbor and a hypothesis is offered about the mechanisms involved.
A comparative neuroanatomic study of retinal projections in two fishes: Astyanax hubbsi (the blind cave fish), and Astyanax mexicanus
Authors: Voneida Theodore J. , Sligar Catherine M.
Published: May 2005

Retinofugal projections in the blind cave fish A. Hubbsi and in the highly visual A. Mexicanus were studied with both reduced silver and autoradiographic methods. Contrary to what has been reported for other teleosts, ipsilateral, as well as the generally accepted contralateral, projections were found in A. Mexicanus. Bilateral retinofugal projections were traced to the dorsolateral thalamic nucleus and area pretectalis. Contralateral projections were traced to the lateral geniculate nucleus, nucleus pretectalis, accessory optic nucleus, nucleus corticalis, nucleus opticus hypothalamicus and the superficial layers of the optic tectum (strata opticum, fibrosum and griseum superficiale, and the cellular zone of griseum centrale).

Retinal efferents in the blindfish, A. Hubbsi, are sparse and totally crossed. Areas receiving a retinal projection include nucleus opticus hypothalamicus, lateral geniculate and the superficial layers of the medial third of the optic tectum. Preliminary behavioral studies are described and discussed in relation to the possible visual potential of this teleost.
Opossum somatic sensory cortex: A microelectrode mapping study
Authors: Pubols Benjamin H. , Pubols Lillian M. , Dipette Donald J. , Sheely Jay C.
Published: May 2005

Organization of opossum somatic sensory cortex has been investigated utilizing closely spaced microelectrode penetrations (0.25–0.5 mm apart) and delicate mechanical stimulation of body surfaces including the facial vibrissae. Results may be summarized as follows: (1) the general organization of somatic sensory cortex, as originally defined by Lende ('63a) has been confirmed; (2) a double representation of the contralateral mystacial vibrissae and rhinarium, implicit in Lende's original data, was revealed in detail, the two representations being orderly, adjacent, mirror‐images of each other; (3) units at a given cortical locus responded to deflection of between one and five mystacial vibrissae, about half responding to movement of a single vibrissa only; (4) about 40% of mystacial vibrissa units showed a directional specificity to the extent that they responded to deflections in only one or two cardinal directions; (5) units located in the medial vibrissa area showed a greater directional specificity than did units located in the lateral vibrissa area; (6) the surface area of rhinarial receptive fields was about ten times the area of first‐order rhinarial unit receptive fields (B. Pubols et al., '73); (7) representation of the contralateral forelimb, especially the ventral surface of the forepaw, is extensive, orderly, and precise; (8) representation of the contralateral hindlimb, foot, and tail is minimal, and is confined to the midline convexity; (9) the presence of a small region of bilateral representation, lateral to the regions of contralateral representation, was confirmed. It is suggested that the region of contralateral postcranial representation plus the medial rhinarium and mystacial vibrissa areas are the homologue of SmII in placental mammals, and the region of bilateral representation is homologous to SmII of placental mammals, but that the lateral vibrissa and rhinarium areas are a specialization of somatic sensory cortex unique to the Virginia opossum.
Projections of the locus coeruleus and adjacent pontine tegmentum in the cat
Authors: McBride Russell L. , Sutin Jerome
Published: May 2005

The projections of the locus coeruleus and adjacent pontine tegmentum have been studied using anatomical and physiological methods in the cat. Axonal trajectories were traced using either the Fink‐Heimer I method following electrolytic lesions, or the autoradiographic method after injection of tritiated proline into the nucleus. Results with both methods were similar. Axons of locus coeruleus neurons ascended ipsilaterally through the mesencephalon lateral to the medial longitudinal fasciculus, ventrolateral to the central gray. In the caudal diencephalon, the ascending fibers entered the centrum medianum‐parafascicular complex where they diverged into two fascicles; a dorsal fascicle which terminated in the intralaminar nuclei of the thalamus, and a ventral fascicle which gave off fibers to the ventrobasal complex and reticular nucleus of the thalamus while continuing ventrolaterally into the lateral hypothalamus medial to the internal capsule. Fibers of the ventral fascicle ascended in the lateral hypothalamus and zona incerta and were traced through the preoptic region into the septum. Fibers could not be consistently traced to the cerebral cortex, and were not seen at all in the cerebellum.

Throughout the ascending course of the path from the locus coeruleus, axons were given off to the pretectal area, the medial and lateral geniculate nuclei, and the amygdala; fibers passed contralaterally through the posterior commissure, the midline thalamus, and the supraoptic commissure. Fibers descending from the locus coeruleus surrounded the intramedullary portion of the facial nerve and further caudally were observed ventrolateral to the hypoglossal and dorsal vagal nuclei.

The axonal trajectories visualized with degeneration and autoradiographic methods followed closely those previously shown for reticular formation neurons, but were also similar to locus coeruleus projections revealed by histofluorescence methods. After injections of horseradish peroxidase into the centrum medianum‐parafascicular complex, lateral hypothalamus or preoptic region, labeled neurons were located in the locus coeruleus, nucleus subcoeruleus, and lateral parabrachial nucleus. Reticular formation neurons were not labeled. Neurons in locus coeruleus and adjacent pontine tegmentum could be antidromically activated by stimulation in the rostral midbrain or caudal diencephalon.

Our data indicate that both adrenergic and non‐adrenergic neurons of the dorsolateral pontine tegmentum have similar projections.
Fine structure of synaptic vesicles in two types of nerve terminals in crayfish stretch receptor organs: Influence of fixation methods
Authors: Tisdale Ann D. , Nakajima Yasuko
Published: May 2005

Crayfish stretch receptor organs were used. The standard procedure consisted of primary fixation with a 1.6% glutaraldehyde solution containing either buffer which was 60% hyposmotic or buffer which was isosmotic with the physiological solution )440 milliosmols(, washing with isosmotic buffer, and postfixation with an isosmotic 1% osmium tetroxide solution. Under these conditions, we encountered two types of nerve terminals; small‐vesicle terminals )SVTs( containing small elongated vesicles )300 ∼ 330 Å( and largevesicle terminals )LVTs( containing larger round vesicles )430 Å(. Their location and physiological evidence suggest that SVTs and LVTs are inhibitory and excitatory, respectively. A hyperosmotic primary fixation solution due to increased glutaraldehyde concentration gave results similar to the standard procedures, while a hyperosmotic primary fixation solution due to increased buffer concentration caused shrinkage of the nerve terminal. A hyperosmotic buffer wash produced elongation of vesicles in SVTs and LVTs, while washing with hyposmotic buffer rendered vesicles in both types round. Direct fixation with isosmotic osmium tetroxide yielded less elongated vesicles in SVTs and irregularly round vesicles in LVTs. However, under all conditions, vesicles in SVTs were smaller than those in LVTs. These results suggest that the consistent morphological difference in vesicles between SVTs and LVTs is size rather than shape, and it is important to standardize the osmolarity of primary fixation and washing solutions when discussing the differences of vesicle shape in various kinds of synapses.
Rate of climbing fiber degeneration in rabbit cerebellum following parafloccular stalk and medullopontine lesions
Authors: Mejia Hugo
Published: May 2005

To resolve inconsistencies in experimental studies which use reduced silver methods to detect cerebellar climbing fiber sources within the brain stem, an evaluation of the temporal course of degeneration was undertaken. The paraflocculus of the rabbit is uniquely situated within the temporal bone and connects with the corpus cerebelli via a stalk passing through a bony foramen. A unilateral electrolytic lesion deafferented the paraflocculus without disturbing blood supply or causing other damage (18 animals). Comparatively, another group of unilateral lesions was placed at the dorsolateral pontomedullary junction, adding significantly to the cortical area deafferented (12 animals). Animals of each group were killed at successively longer intervals commencing at 18 hours, and a modified Fink‐Heimer impregnation process was applied to the cerebellar cortex and opposite‐sided controls.

In parafloccular lesions, degeneration was detected at 24 hours in the climbing fibers of the molecular layer. At successively longer intervals, degeneration became increasingly evident in granule layer and white matter. Subsequent to dorsolateral pontomedullary lesions, climbing fiber degeneration was first observed in the molecular layer at 24 hours and was clearly evident there at 36 hours. By 72 hours degeneration had reached the white matter, meanwhile disappearing in the molecular layer where it was first seen.

Using techniques of Nauta‐Fink‐Heimer to display secondary climbing fiber degeneration in cerebellar cortex, it was found that too long post‐operative intervals could preclude its detection, since in both groups of animals it commenced earlier and disappeared sooner in the molecular layer.
Effects of visual deprivation and alterations in binocular competition on responses of striate cortex neurons in the cat
Authors: Kratz Kenneth E. , Spear Peter D.
Published: May 2005

Electrophysiological recordings were made from single neurons in striate cortex of normally reared kittens (group N), kittens raised with binocular lid‐suture (group BD), and kittens raised with one eye lid‐sutured and the other eye removed (group MD‐E). The MD‐E group represents a condition in which inputs from the deprived eye have been placed at a competitive advantage over those from the other eye.

In agreement with previous studies, fewer cells were responsive to visual stimulation in BD kittens than in N kittens. Among the responsive cells, fewer were direction selective, fewer were orientation selective, and more had inconsistent or fast‐adapting responses than in normals. The responsiveness and receptive field properties of striate cortex neurons in the MD‐E kittens were less affected by the visual deprivation than in BD kittens; however, they still were abnormal in comparison to normal kittens.

Comparison of the ocular dominance distributions for cells in N and BD kittens showed a marked reduction in binocularly driven cells in BD kittens. In addition, in BD kittens, a larger proportion of monocularly driven cells had orientation selective receptive fields than did binocularly driven cells. This difference was not found in normally reared kittens.

The results of this study suggest that abnormal binocular interactions contribute to the effects of visual deprivation following binocular lid‐suture, probably due to asynchronous light‐dark inputs through the closed lids. Removing the other eye and placing inputs from the deprived eye at a competitive advantage during development results in decreased effects on striate cortex neurons. Nevertheless, visual deprivation still produces abnormalities in striate cortex independent of asynchronous or uncorrelated visual stimulation of the two eyes.
Selective uptake and transport of label within three identified neuronal systems after injection of 3H‐GABA into the pigeon optic tectum: An autoradiographic and golgi study
Authors: Hunt S. P. , Künzle H.
Published: May 2005

After injection of tritiated gamma‐aminobutyric acid (GABA) into the pigeon optic tectum and thalamus it was possible to correlate certain aspects of the autoradiographic labelling pattern with observations made from Golgi material. Three neuronal, GABA specific systems were identified both from the uptake of the amino acid and from the subsequent and bidirectional intracellular transport of label.

The first system derives from cell bodies within sublayer IIi the axons of which could be selectively labelled throughout their course within layer I and to the areas of termination within the pretectum and ventral thalamus. The radially ascending dendrites and axon collaterals of these neurons arbourised within sublayer IIf, and could be labelled in a retrograde fashion after tectal or thalamic injections.

The second system was represented by small perikarya within sublayer IIc with locally and superficially directed dendrites and with a radially and deep directed axon from which an extensive axon collateral system arose. It was found possible to label these perikarya either directly or indirectly after tangential tectal injections which preferentially labelled the axons and terminals of these neurons within the deeper regions of the tectal cortex and resulted in the retrograde axonal movement of label to the overlying cell bodies.

A third system was found within sublayer IId, was horizontally organized and from a correlation with degeneration, other autoradiographic and Golgi preparations thought to be mainly dendritic in nature.

The biochemical and anatomical implications of specific GABA uptake and subsequent transport of label are discussed and a model of the tectal cortex, based on the three proposed inhibitory systems and their relation to a number of tectal afferent inputs, considered.
Electron‐microscopic identification of Marchi‐positive bodies and argyrophilic granules in the spinal cord white matter of the guinea pig
Authors: Hildebrand Claes , Aldskogius Håkan
Published: May 2005

Sections from spinal cord white matter of normal and rhizotomized guinea pigs fixed by glutaraldehyde perfusion were stained with Marchi fluid or according to a suppressive silver technique. With the aid of the section‐embedding method thin sections, cut from light‐microscopically identified areas containing Marchi‐positive bodies or argyrophilic granules, were examined in the electron microscope.

The results show that the Marchi‐positive bodies and argyrophilic granules, which are present in normal white matter, represent different histochemical expressions of the same entity — the myelinoid body. In view of the similarities between myelinoid bodies and myelin fragments formed during Wallerian degeneration it is suggested that this type of so called artifact staining of normal white matter inherent to both methods should instead be considered as an expression of a specificity of the two methods for degenerating nervous elements.
Structural and functional changes in an identified cricket neuron after separation from the soma. II. Functional changes
Authors: Clark Richard D.
Published: May 2005

Physiological and behavioral effects of separation from the soma were examined in isolated arborization and isolated axon segments of an identified motor neuron in the Polynesian field cricket, Teleogryllus oceanicus. The identified neuron, the contralateral dorsal longitudinal motor neuron of the metathoracic ganglion (CDLM), has an arborization most of which lies contralateral to its soma within the ganglion. Midline lesions in the ganglion separated CDLM into a distal segment composed of the axon and most of the arborization, and a proximal segment made up of the remaining arborization, neurite and soma. Isolated axonal segments were produced by cutting the nerve containing the CDLM axon.

The function of the neuron‐muscle system composed of CDLM, its pre‐synaptic inputs, and its innervated muscle bundle was examined in control and experimentally operated animals. Extracellular recording assessed function in the axon. Electrical or tactile stimulation was used to excite pre‐synaptic inputs to the CDLM arborization. Intracellular recording determined changes in postsynaptic potentials and miniature end‐plate potentials in the muscle bundle innervated by CDLM.

Normal axonal conduction, competence to respond to pre‐synaptic input, neuron‐muscle transmission, and miniature end‐plate potential appearance can remain in the isolated arborization preparation. Physiological viability is longer in the cricket isolated arborization than in other insect distal segments described. Survival times of axonal conduction and the competence of the isolated arborization to respond to pre‐synaptic input are roughly correlated with disappearance of the whole distal segment at 100 or more postoperative days. A naturally‐occurring breakdown of the metathoracic dorsal longitudinal muscles in Teleogryllus eventually prevents measurements of post‐synaptic potentials and miniature end‐plate potentials. Normal post‐synaptic function mediated by the distal arborization is maintained up to this breakdown, to a maximum of 44 days postoperative.

The distal axonal segment of CDLM degenerates physiologically within four days postoperative, a time course approximating that of degeneration in vertebrate peripheral nerve distal axons.
Developmental studies of thalamocortical and commissural connections in the rat somatic sensory cortex
Authors: Wise S. P. , Jones E. G.
Published: May 2005

Autoradiographic, axonal degeneration, and horseradish peroxidase fiber tracing methods were employed to investigate the organization, development and potential plasticity of the thalamocortical projection to the somatic sensory cortex of the rat. In the adult animal, thalamocortical terminals are concentrated primarily in layers I and IV and in the upper part of layer VI. Fibers terminating in layers IV and VI arise from a different thalamic region than those terminating in layer I. Discrete clusters of fibers and terminals 250–450 μm wide are distributed only to the parts of the SI cortex containing dense aggregates of layer IV granule cells and not to the intervening, less granular and commissurally connected zones.

At birth, thalamocortical fibers have invaded the deep part of the developing SI cortex and are concentrated in the upper part of layer VI. Between the age of two and three days, an additional concentration of fibers appears in the part of the cortical plate which will become layer IV. Layer IV is clearly recognizable by three days of age and the dense granule cell aggregates appear in it no more than one day later. The ingrowth of commissural fibers (Wise and Jones, '76) lags behind that of thalamic fibers. The mature commissural fiber pattern is not established until the age of seven days.

After removal of the developing thalamocortical system by thalamotomy in newborn rats, subsequent investigation of the commissural system in the adult showed that no commissural fibers or terminals had invaded either laminae or zones of the cortex deprived of thalamic input. Similarly, commissurotomy at birth was not followed by sprouting of thalamic fibers into zones or laminae deprived of commissural connections. The connectional specificity observed in these neocortical fiber systems contrasts markedly with the plasticity of connections reported in allocortical systems.

Removal of thalamocortical afferents before they attain their definitive distribution does not radically effect the overall development of the dense granule cell aggregates in layer IV. Within the aggregates, however, subsidiary features such as the “barrels” fail to appear. This finding suggests that certain elements of cortical architecture such as the dense granule cell aggregates are independent of thalamic afferents while others, such as the barrels, result from the interaction of the developing thalamocortical fibers and/or terminals with maturing neurons.
A neuroanatomical study of the cochlea of the little brown bat (Myotis lucifugus)
Authors: Ramprashad Fred , Money Kenneth E. , Landolt Jack P. , Laufer Jerry
Published: May 2005

The population and density of the bipolar ganglion cells and sensory hair cells were determined from serial sections and graphic reconstructions of the cochlea and spiral ganglion of four little brown bats. The spiral ganglion lacks a bony canal and is a one and one‐half turn spiral of almost uniform thickness which ends in a broad flat nodule at its apex. The average length of the nerve cell body is 7.4 μ (range: 5–15 μ) and it is 6.4 μ wide (5–10 μ). The average number of ganglion cells enumerated was 63.2 × 103 (range: 60.6 × 103–65.2 × 103) and following correction for “split cell error,” the total number was 55.3 × 103 ganglion cells. The ganglion cell density curve increases gradually to a maximum value of 11.7 × 103 cells/mm2 at 2.4–3.2 mm from the basal end. The two and one‐half turn cochlea is 6.9 mm long (6.8–7.1 mm) with an estimated total of 700 inner and 2,800 outer sensory hair cells. The densities of outer and inner hair cells increase from the base to the apex by 21% and 32%, respectively. However, the density of sensory cells per unit of sensory epithelium decreases from base to apex. The ratio increases to a maximum value of 22:1 at 2.4 mm and then declines toward the apex. The significance of these findings is discussed and compared to similar studies on other high‐frequency hearing mammals.
A quantitative analysis of the innervation of the pulp of the cat's canine tooth
Authors: Beasley W. L. , Holland G. R.
Published: May 2005

Although the cat's canine tooth has become the accepted model for the electrophysiological study of dental sensory mechanisms no examination of its innervation has been carried out at the electron‐microscopical level. This study looked at the number and size distribution of both myelinated and non‐my‐elinated fibers in the crown of the cat's canine. The material examined was prepared by routine methods and the measurements taken from electron‐microscopical montages of pulpal cross‐sections. The measurements were made using a Quantimet 720 image analysis system. In one complete cross‐section 3,470 fibers were counted. Eighty‐one percent of these were non‐myelinated with a modal diameter of 0.35 μm. The modal diameter of the myelinated fibers was 2.5 μm. The relative preponderance of non‐myelinated fibers increased from core to periphery. The largest myelinated fibers were concentrated in the core. The fiber size distribution was similar in the single complete and two partial sections examined. It is concluded that all the fibers in the crown of the cat's canine would be contained in the A‐delta and C groups and that the strikingly large number of fibers present suggests that the peripheral pulp has a dense innervation, many of the cell processes found there being unsheathed axons.
Histochemical evidence for a post‐lesion reorganization of cholinergic afferents in the hippocampal formation of the mature cat
Authors: Steward Oswald , Messenheimer John A.
Published: May 2005

We have utilized acetylcholinesterase (AChE) histochemistry to analyze possible post‐lesion changes in the distribution of AChE containing afferents to the hippocampal formation of the cat following unilateral destruction of the entorhinal cortex. In the cat, the entorhinal area gives rise to a massive projection to the ipsilateral fascia dentata, and to regio inferior and regio superior of the hippocampus proper. Sixty days following unilateral entorhinal lesions, histochemical preparations for AChE indicate a dramatic increase in the density of the reaction product in the zones normally occupied by entorhinal afferents in the fascia dentata and regio inferior of the hippocampus proper, whereas little if any increase in the density of the reaction product was observed in the entorhinal terminal zone in regio superior. In addition to these increases in the density of the AChE reaction product, there was also evidence for a widening of an AChE free zone in the inner stratum moleculare of the fascia dentata denervated by the lesion. The time course of these changes in the pattern of AChE staining was analyzed by sacrificing animals 7, 10, 13, 14, 16, 17, 19, and 20 days following entorhinal cortical lesions. The increase in the density of the AChE reaction product in the denervated zones was not apparent at seven days post‐lesion, while at ten days post‐lesion, a slight increase in the density of the AChE reaction product could be observed. By 13 days post‐lesion, the differences between the denervated and normally innervated (contralateral) hippocampal formation were prominent, and by 16 days post‐lesion, the pattern of staining appeared comparable to that which was observed at longer post‐lesion intervals. The present experiments indicate that following entorhinal cortical lesions in mature cats the final post‐lesion pattern of altered AChE staining is quite comparable to that which is observed following similar lesions in rats. In the rat, such changes in AChE staining have been interpreted as a reflection of a proliferation of cholinergic septal afferents within the denervated zones. If this interpretation is correct, the present results suggest a similar proliferation of cholinergic afferents following entorhinal lesions in cats. The time course of this apparent proliferation is considerably slower in the cat then in the rat, however, since the earliest changes are observed at approximately five days post‐lesion in the rat, and ten days post‐lesion in the cat.
The effect of refeeding after neonatal starvation on purkinje cell dendritic growth in the rat
Authors: McConnell P. , Berry M.
Published: May 2005

Male rats, undernourished from birth until 30 days by restricting access to the lactating dam, were given ad libitum food supplies until 80 days. Body weight, whole brain weight and cerebellar weight remained significantly lower in these animals than in normally fed controls. Significant deficits in the area of the molecular and granular layers persisted at 80 days, although there was some recovery during the refeeding period. At the same time granule and Purkinje cell density declined, suggesting that the areal recovery was due to the expansion of the interneuronal matrix. Granule cell numbers remained unchanged between 30 and 80 days.

Network analysis of Golgi‐Cox preparations indicated a 28% decrease in overall size of the Purkinje cell dendritic networks, due primarily to a deficit in segment frequency which remained unchanged throughout the rehabilitation period. Segment length did, however, show some recovery; distal segments from 80‐day experimental networks were significantly longer than those of 30‐day undernourished animals. The results of the topological analysis suggested that dendritic remodelling had taken place during the rehabilitation period.

The failure to observe a complete recovery in the size and morphology of the dendritic network may be explained in terms of recent suggestions that dendritic development is influenced both by the metabolism of the neurons themselves, and by the number and density of adjacent afferent axons. It is suggested that refeeding from 30 days leads to the recovery of Purkinje cell metabolism, but is unable to restore the parallel fiber deficit.
Abnormalities of the cortico‐geniculate pathway in siamese cats
Authors: Montero V. M. , Guillery R. W.
Published: May 2005

The cortico‐geniculate pathways of normally‐pigmented and Siamese cats have been studied by autoradiography following injections of 3H proline into cortical area 17. Normal Siamese cats and Siamese cats that were raised with one eye sutured or removed have been compared with normally‐pigmented cats treated in the same manner. The cortico‐geniculate projection from area 17 passes to all parts of the lateral geniculate nucleus in normal cats and distributes to all geniculate layers (Updyke, '76). This distribution was essentially unaffected by an early monocular suture or enucleation. In Siamese cats, the cortico‐geniculate projection to lamina A and to the lateral normal segment of lamina A1 was normal, but little or no label was seen in the abnormal segment of lamina A1. The interlaminar zones adjacent to the abnormal segment of lamina A1 were densely filled with label, as though the cortico‐geniculate axons avoid this segment. Unilateral enucleation or lid‐suture did not affect this distribution, suggesting that it does not depend upon visual experience. These Siamese cats were all identified by electrophysiological studies as having a normal topography of the geniculo‐cortical pathways. That is, they were “Midwestern” cats.
The sensory trigeminal system of a snake in the possession of infrared receptors. II. the central projections of the trigeminal nerve
Authors: Molenaar Gerard J.
Published: May 2005

The central projections of the sensory roots of the trigeminal nerve in Python reticulatus have been studied by means of the Fink Heimer technique following transsection of these roots between the trigeminal ganglia and the brainstem.

The sensory trigeminal fibres are distributed to the two separate sensory trigeminal systems, described before, i.e., the common sensory and the lateral descending trigeminal system. The projections of the three peripheral trigeminal branches are restricted to their own territories of the various tracts and nuclei. Generally, the ophthalmic root projects most ventrally; the mandibular root most dorsally and the maxillary root intermediately. The ophthalmic branch descends until the level of the first cervical nerve root, the maxillary and mandibular branches proceed beyond the second cervical nerve roots.

The distribution pattern of the sensory trigeminal fibres differs in two major aspects from that of other vertebrates. The first difference is a large overlap of the projection areas from the mandibular and maxillary roots. The probable occurrence of this overlap within other, mammalian, species is discussed. The second major difference is the projection into the lateral descending trigeminal nucleus. The morphology of the degenerating fibres and “boutons terminaux” in this lateral descending system is markedly different from that within the common sensory system.

Preliminary notes are presented to show that the common sensory and the lateral descending systems project to different areas in the mesencephalon and diencephalon. It will also be shown that the nucleus of the lateral descending trigeminal tract is exclusively concerned in processing the infrared information relayed by the pit organs.

The possibility of the presence of a separate trigeminal system in other vertebrates, equivalent to the lateral descending trigeminal system of the python, is discussed.
Estimate of the number of myelinated axons in the cat's optic nerve
Authors: Stone Jonathan , Campion Joyce E.
Published: May 2005

The number of myelinated axons in the cat's optic nerve has been estimated from a partial count of sections of the nerve examined by electron microscopy. The average count obtained from four nerves was 128,600 (range 112,800‐147,200). This figure is within 10% of a previous estimate of the number of ganglion cells in the cat's retina, but is 33% lower than the only previous estimate of the number of these axons based directly on electron microscopy. Possible sources of the discrepancy are discussed.

The functional implication of this total, in the context of earlier work on ganglion cell topography, are also discussed.
Altered retinal projection in brushtailed possum, trichosurus vulpecula, following removal of one eye
Authors: Sanderson K. J. , Pearson Lyn J. , Dixon Pam G.
Published: May 2005

One eye was removed from ten brushtailed prossums aged 18 to 102 days. The possums were kept until they reached 8‐13 months of age and the remaining eye was injected with 3H leucine to show the retinal projections. Retinal projections were also mapped in five normal possums.

In the one‐eyed possums we found an altered retinal projection to the medial terminal nucleus (MTN), the dorsal lateral geniculate nucleus (LGNd) and the superior colliculus (SC). In normal possums the MTN receives an contralateral retinal projection. The LGNd has a laminar structure, there being three contralateral laminae and five ipsilateral laminae. In normal possums there is a contralateral retinal input to the superficial layers of the SC and in the front half of the SC there is an ipsilateral input top the deeper layers.

In the one‐eyed possums we observed a bilateral retinal projection to the MTN. This was best developed in possums which had lost one eye at an early age (about 25 days). In the one‐eyed possums there was an extensive retinal projection to the superficial layers of the ipsilateral SC in addition to the normal retinal projection to the contralateral SC. In animals which had lost one eye at about 25 days the retinal fibers covered about three‐quarters of the ipsilateral SC, whereas in animals which had been operated at about 80 days the retinal fibers occupied only part of the front half of the ipsilateral SC. Animals which had lost one eye at about 80 days showed some growth of retinal axons into the deafferented layers of the LGNd and these layers were thinner than the layers with a normal nerve input. In animals which had lost one eye at 25 to 50 days retinal fibers form the remaining eye covered the whole of the LGNd on both sides.

The possum which lost one eye at age 102 days, when its eyes were open, had retinal pathways which were nearly normal.