bluuebunny/crossref_metadata_2025 huggingface dataset:
Organization of motor pools in the chick lumbar lateral motor column
Authors: Hollyday Margaret
Published: January 2005

Motor pool positions for individual leg muscles were mapped in hatched chicks using intramuscular injections of HRP. Several leg muscles were also mapped in stage 38 (12‐day) embryos. The results indicate that an adult map is formed by stage 38.

The adult motor pool map can be viewed as being composed of two maps, one for muscles derived from the embryonic ventral muscle mass, the other for muscles derived from the dorsal mass. Each of these maps is a continuous, although distorted, representation of muscle precursor position on the original sheets of dorsal and ventral muscle mass. The developmental implications of these findings are discussed.
The afferent ganglion cells and cortical projections of the retinal recipient zone (RRZ) of the cat's ‘pulvinar complex’
Authors: Leventhal Audie G. , Keens Jeremy , Törk Istvan
Published: January 2005

A retino‐pulvinar projection in the cat was confirmed using anterograde (autoradiography) and retrograde (horseradish peroxidase (HRP) tracing techniques. The part of the ‘pulvinar complex’ receiving retinal afferents is referred to as the retinal recipient zone (RRZ). The cortical projections of the RRZ were studied by injecting HRP into different cortical areas. The retrograde labeling of the cell bodies and dendritic fields of the retinal ganglion cells projecting to the RRZ was accomplished by injecting HRP electrophoretically into the RRZ.

Our results indicate that the RRZ projects to areas 19 and the lateral suprasylvian area (LS) but not to areas 17 or 18. Virtually all RRZ cells, including those that project to the cortex, are small (10–20 μm in diameter); they are the same size as the relay cells of the parvocellular C laminae of the lateral geniculate nuclear complex (LGNd) that project to areas 19 and LS.

The majority of the ganglion cells projecting to the RRZ had medium‐sized somas (15–25 μm in diameter), large (up to 800 μm in diameter), diffuse dendritic fields with a characteristic morphology, and appeared different form the alpha, beta, gamma, and delta cells of Boycott and Wässle (′74). These cells provide evidence for another morphological class of ganglion cells, termed epsilon cells.

Our results suggest that the RRZ relays the activity of specific types of retinal ganglion cells to extrastriate visual cortex and, thus, functions in parallel with the different subdivisions of the LGNd.
Fine structure and synaptic connections of the common spiny neuron of the rat neostriatum: A study employing intracellular injection of horseradish peroxidase
Authors: Wilson Charles J. , Groves Philip M.
Published: January 2005

Medium‐sized spiny neurons of the rat neostriatum, identified by intracellular injection of horseradish peroxidase, were examined at both light and electron microscopic levels. These neurons were characterized by their heavy investment of dendritic spines, beginning about 20 μm from the soma and continuing to the tips of the dendrites. Their axons arose from the soma or from a large dendritic trunk very near the soma, and tapered rapidly to form a main axonal branch from which arose several smaller initial collaterals. These arborized extensively throughout an area of about the same size as, and highly overlapping with, the dendritic field of the cell, while the main axon could be followed for distances of up to 1 mm in the direction of the globus pallidus. Three major synaptic types were seen in contact with spiny neurons.

Boutons containing small round synaptic vesicles formed synapses exclusively with spiny regions of the dendrites, and most of these were axo‐spinous. Small, very pleomorphic synaptic vesicles characterized a second bouton type of unknown origin, which made contacts with somata, initial segments, and dendrites, but not dendritic spines. Boutons containing large pleomorphic synaptic vesicles had the most widespread distribution, contacting all regions including dendritic spines. Spines receiving these contacts also were postsynaptic to boutons containing small round vesicles. Axon collaterals of spiny cells formed synapses with large pleomorphic vesicles and made synapses with somata, initial segments of axons, dendrites, and dendritic spines of striatal neurons, including other spiny cells.
Central myelin in the mouse mutant shiverer
Authors: Rosenbluth J.
Published: January 2005

The Spinal cord, optic nerves, and cerebellum of the mouse mutant Shiverer were examined by electron microscopy of thin sections. Although central nervous system myelin in grossly deficient in amount, one of its basic structural elements are missing. Regions of compact myelin cat be found composed of several layers of alternation major dense lines and intermediate lines repeating with normal periodicity. The “radial component” consisting of periodic thickenings of the intermediate line aligned through several lamellae was also identified. Axoglial junctions characteristic of the type found in paranodal regions are present in greater than normal numbers but occur in aberrant locations. Myelin sheaths have markedly reduced numbers of lamellae, which often contain cytoplasm terminate in cytoplasmic “loops” within and around myelin sheaths, and do no completely encircle axons. In addition, membranous debris appears within neuronal and glial profiles, suggesting some degree of myelin breakdown. Thus, the protein lacks in this mutant appear not to be associated with discrete deficiencies of specific structural components but rather with a variety of quantitative changes and irregularity of form.
A specialized type of neuron in the visual cortex of cat: A Golgi and electron microscope study of chandelier cells
Authors: Fairén A. , Valverde F.
Published: January 2005

The axonal arborization of chandelier cells is characterized by its conspicuous, vertically oriented, bouton aggregates. The efferent synaptic relationships established by these terminal formations were investigated by electron microscopy of Golgi preparations after gold toning and deimpregnation. In all cases examined form layers II and III of cat areas 17 and 18, the terminal formations, here denominated specific terminal portions (stp), make symmetric synapses upon axon initial segments of pyramidal neurons. Some identified stp's were reconstructed from ultrathin serial sections with the aid of a microcomputer‐based system, and the number of synaptic contacts established on axon initial segments was evaluated. No evidence was found that parts of the axonal tree other than stp's also engage in synaptic contacts.

Specific terminal portions are rather variable in complexity. However, the synaptic contacts they engage in are constant and the complexity of stp's from the same axonal arborization varies. It is, therefore, clear that all stp's are terminal axonal formations of a unique, specialized type of neuron.

Computer techniques and conventional Golgi observations were used to study further details of chandelier cell morphology. Axonal plexuses are preferentially, although not exclusively, local and distribute within spheric, ovoid, or disk‐shaped spaces In most chandelier cells, the main axonal trunk descends to the white matter, where we have been unable to follow it further.
An EM analysis of the synaptic connections of horseradish peroxidase‐filled stalked cells and islet cells in the substantia gelatinosa of adult cat spinal cord
Authors: Gobel Stephen , Falls William M. , Bennett Gary J. , Abdelmoumene Mohammed , Hayashi Haruhide , Humphrey Emma
Published: January 2005

Two major interneurons of the outer part of Rexed's layer II (IIa) were impaled with microelectrodes, had their primary inputs characterized, and were subsequently filled with horseradish peroxidase. Their fine structural characteristics and synaptic connections were then analyzed electron microscopically. Two islet cells, whose rostrocaudally oriented dendrites were largely confined within layer IIa, received primary input form small myelinated axons. A stalked cell, whose cell body was situated on I/II border had a cone‐shaped dendritic arbor which traversed layer IIa as well as the inner part of Rexed's layer II (IIb) and rostrocaudal dendritic branches which ran for part of their course along the I/IIa border. It received primary input from small myelinated as well as form unmyelinated axons. Both cell types received asymmetrical axodendritic synapses from primary endings in layer IIa and IIb glomeruli and widely separated symmetrical axodendritic synapses from small nonprimary endings outside of glomerli.

The presence of aggregates of synaptic vesicles in the dendrites of the layer IIa islet cells but not in the staked cell dendrites constitutes the major fine structural difference between these interneurons. Islet cell dendtrites from symmetrical synapses on several different kinds of neural processes. They usually send either a single type 2 spine (spines which contain synaptic vesicles) or dendtritic shaft into layer IIa and IIb glomeruli, where they form dendrodendritic synapses on adjacent type 1 spines (spines without synaptic vesicles) and on other small dendritic shafts. Some islet cell type 2 spines also form dendroaxonic synapses on the primary endings.

Outside of the glomeruli, islet cell dendrites also form dendrodendritic synapses on type 1 spines and different sized dendritic shafts. They often approach other dendritic shafts. They often approach other dendritic shafts forming small bundles of dendrites in which they are reciprocally linked by dendrodendritic synapses to other synaptic vesicle‐containing dendrites. At bead‐like enlargements of their dendritic shafts and along some of the shafts of unmyelinated axons. The unmyelinated axon of the islet cell forms symmetrical synapses on layer II dendritic shafts and spines outside of glomeruli. The role of the layer IIa islet cell as an inhibitory interneuron is discussed.
Development of the brain stem in the rat. III. Thymidine‐radiographic study of the time of origin of neurons of the vestibular and auditory nuclei of the upper medulla
Authors: Altman Joseph , Bayer Shirley A.
Published: January 2005

Groups of pregnant rats were injected with two successive daily doses of 3H‐thymidine form gestational days 12 and 13 (E12 + 13) until the day before parturition (E21 + 22). In adult progeny of the injected rats the proportion of neurons generated on specific embryonic days was determined quantitatively in the vestibular and auditory nuclei of the upper medulla. In the vestibular nuclei, neurons are generated between days E11 and E15 in an overlapping sequential order, yielding a lateral‐to‐medial and a rostral‐to‐caudal internuclear gradient. In the lateral vestibular nucleus peak production time is day E12; in the superior nucleus, E13; in the inferior nucleus, E13 and E14; and in the medial nucleus, E14. The early generation of neurons of the lateral vestibular nucleus may reflect the early differentiation of the circuit from the gravity receptors (utricle) to neurons of the spinal cord controlling postural balance. The later production of neurons of the superior vestibular nucleus may reflect the subsequent differentiation of the circuit from the rotational receptors (semicircular canals) to the neurons of the brain stem controlling eye movements. The generation time of neurons of the nucleus prepositus hypoglossi overlaps with that of the medial vestibular nucleus.

The neurons of the anteroventral and posteroventral cochlear nuclei are produced form days E13 to E17, with no temporal differences between the two nuclei. The neurons of the dorsal cochlear nucleus are generated over a very long time span, beginning on day E12 and extending into the postnatal period. There is a sequence in the production of neurons forming the different layers of the dorsal cochlear nucleus in the following order: pyramidal cells, cells of the inner layer, cells of the outer layer and, finally, cells of the granular layer. There is also a sequential production of neurons in four nuclei of the superior olivary complex. In the lateral trapezoid nucleus peak production time is day E12; in the medial superior olivary nucleus, day E13; in the medial trapezoid nucleus, day E15; and in the lateral superior olivary nucleus, day E16. This order yields a medial‐to‐lateral gradient in the dorsal aspect of the superior olivary complex, and a lateral‐to‐medial gradient ventrally. These mirror‐image gradients were also seen intranuclearly in the lateral superior olivary nucleus and the medial trapezoid nucleus. The cytogenetic gradients could not be related to tonotopic representation; however, they could be related to the lateral location of ipsilateral cochlear nucleus input to the lateral superior olivary nucleus and the medial location of the contralateral cochlear nucleus input to the medial trapezoid nucleus.
Glial fibrillary acidic protein in the retina of the developing albino rat: An immunoperoxidase study of paraffin‐embedded tissue
Authors: Dixon Richard G. , Eng Lawrence F.
Published: January 2005

The peroxidase‐anti‐peroxidase method was used on paraffin‐embedded material to demonstrate the distribution of glial fibrillary acidic (GFA) protein, an astrocyte‐specific protein, in the developing retina of the albino rat. At birth activity was scant and was confined to scattered, poorly differentiated cells in the inner retinal layers near the optic disc. At 3 days primitive astrocytes which displayed GFA protein activity were confined to the stratum opticum near the optic disc. With increasing age these cells were found at greater distances from the optic disc and began to assume the appearance of typical fibrous astrocytes. By 30 days the perikarya of these cells were confined almost exclusively to the region between the nerve fiber layer and the inner limiting membrane. The processes of these cells terminated either in suckerlike end‐feet upon blood vessels or, to a lesser extent, ended in relation to axon fascicles of the nerve fiber layer.

A second population of GFA protein‐active cells existed as perivascular glia which were found upon vessels in the inner portion of the stratum opticum in young animals. In the mature retina perivascular glia were found on vessels throughout the stratum opticum and in the inner portion of the inner plexiform layer.

Unequivocal staining of Müller cells or their processes was not obtained.

The best staining was obtained with fixatives containing minimal concentrations of aldehydes, especially in tissue from younger animals. The fixative which gave the best preservation of cellular structure along with preservation of GFA protein antigenicity was Perfix (Fischer Scientific Company).
Monosynaptic cortical input and local axon collaterals of identified striatonigral neurons. A light and electron microscopic study using the golgi‐peroxidase transport‐degeneration procedure
Authors: Somogyi P. , Bolam J. P. , Smith A. D.
Published: January 2005

Following the injection of horseradish peroxidase into the ipsilaeral substantia nigra, 36 retrogradely labelled neurons in the striatum were characterized (in three rats) by Golgi staining and gold toning: each neuron was of the medium‐size, densely spinous type. Prior to the injection of horseradish peroxidase, two of the rats had had lesions placed in the ipsilateral motor cortex, the third rat had had a lesion placed in the ipsilateral frontal and prefrontal cortex. In the electron microscope, degenerating boutons of cortical neurons were found in asymmetrical synaptic contact with the spines of proximal and distal dendrites of all six of the identified striatonigral neurons that were studied. Some of the degenerating boutons were small (diameter 0.1–0.3 μ), while others were larger (1–2 μ). An individual dendrite of a striatonigral neuron was in synaptic contact with very few degenerating boutons

Local axon collaterals im the striatum could be traced from two of the identified striatonigral neurons that received degenerating cortical boutons. These were studied in the electron microscope; their boutons formed symmetrical synapses with spines or dendritic shafts of other striatal neurons. The synaptic boutons contained large, clear, round and pleomorphic vesicles. The postsynaptic targets of these boutons morphologically resemble the dendrites of medium‐size spiny neurons

It is concluded that afferents from the cortex make monosynaptic contact with the dendritic spines of medium‐size spiny striatonigral neurons and that such neurons have local axon collaterals in the striatum that form synapses with other spiny neurons.
Substrate pathways demonstrated by transplanted mauthner axons
Authors: Katz Michael J. , Lasek Raymond J.
Published: January 2005

A substrate pathway is a set of aligned guidance cues. (Such cues may be either cells or molecules). CNS substrate pathways can be demonstrated by transplanting axons to different starting locations. The stereotyped routes of transplanted axons will then demonstrate the locations of effective substrate pathways. To map CNS substrate pathways, Mauthner axons were transplanted to vaious unnatural locations along the CNS of Xenopus embryos. The routes of 24 experimental Mauthner axons were traced. Twenty‐one of these axons grew along parts of a stereotyped route extending in the ventral marginal zone from the caudal diencephalon through the spinal cord. This ventral substrate pathway ran the length of the basal plate; thus, we call it a basal substrate pathway. One experimental Mauthner axon grew along the alar substrate pathway previously demonstrated by transplanted optic axons. The demonstrations of the alar and the basal substrate pathways suggest that during development a few long substrate pathways organize the overall layout of the long tracts of the CNS. We propose that the pattern of the earliest CNS substrate pathways is established in the neural plate and is topologically preserved as the neural plate rolls into a neural tube. This pattern may be manifest as the three‐dimensional organization of the early marginal zones formed by the peripheral processes (the endfeet) of certain developing ependyma and radial glia. Subsequently, the detailed anatomy of the axon tracts and the specific terminations of individual axons are probably determined by other local chemical cues.
Immunohistochemical localization of the 150K neurofilament protein in the rat and the rabbit
Authors: Dahl D. , Bignami A. , Bich N. T. , Chi N. H.
Published: January 2005

Antisera to the 150K‐dalton polypeptide of the bovine neurofilament triplet and chicken neurofilament antisera reacting with the 70K protein in isolated bovine brain filaments stained the same structures in rat cerebellum by immunofluorescence and peroxidase‐antiperoxidase methods, that is Purkinje cell baskets, thin nerve fibers in the lower half of the molecular layer and myelinated axons. The 150K bovine neurofilament antisera did not stain large motor neurons in the anterior horns of the spinal cord in rat and rabbit, nor aluminum‐induced neurofibrillary tangles in the rabbit. All these structures were demonstrated by the chicken neurofilament antisera and by silver neurofibrillary methods. IDPN‐induced axonal balloons containing accumulations of neurofilaments were equally well stained by bovine 150K and chicken neurofilament antisera. These data suggest that the 150K polypeptide of the neurofilament triplet is not a subunit of the neurofilament core and probably plays a role in axonal transport.
An immunohistochemical study of the organization of catecholaminergic cells and terminal fields in the paraventricular and supraoptic nuclei of the hypothalamus
Authors: Swanson L. W. , Sawchenko P. E. , Bérod A. , Hartman B. K. , Helle K. B. , Vanorden D. E.
Published: January 2005

The distribution of catecholaminergic fibers and cell bodies in the paraventricular and supraoptic nuclei of the hypothalamus was investigated with immunohistochemical methods in the adult albino rat. Sections through the nuclei were stained with antisera to the catecholamine synthesizing enzymes tyrosine hydroxylase (TH), dopamine‐ß‐hydroxylase (DBH), and phenylethanolamine‐N‐methyltransferase (PNMT). The results suggest that adrenergic (PNMT‐stained) fibers innervate the entire parvocellular division of the paraventricular nucleus, although the highest density of fibers was found in the medial part of the division. Only widely scattered adrenergic fibers are found in the magnocellular division of the nucleus and in the supraoptic nucleus. Noradrenergic fibers appear to innervate the periventricular zone of the paraventricular nucleus and those parts of the paraventricular and supraoptic nuclei that contain predominantly vasopressinergic neurons in both the normal and in the homozygous Brattleboro rat. Significant numbers—somewhat more than 500—of dopaminergic (TH‐stained) neurons are found in the paraventricular nucleus; the cells are distributed throughout the nucleus but are concentrated in the medial and periventricular parts of the parvocellular division. Double‐labeling experiments with the retrogradely transported tracer true blue indicate that between 4% and 8% of the dopaminergic neurons in the paraventricular nucleus project to the region of the dorsal vagal complex and/or to thoracic levels of the spinal cord. It is concluded that adrenergic inputs to the paraventricular nucleus may influence cells that project to the median eminence and to preganglionic autonomic cell groups in the medulla and spinal cord. Noradrenergic inputs to the supraoptic and paraventricular nuclei may influence primarily vasopressinergic cells that project to the posterior lobe of the pituitary, as well as cells in the periventricular part of the paraventricular nucleus that project to the median eminence.
The genesis of efferent connections from the visual cortex of the fetal rhesus monkey
Authors: Shatz Carla J. , Rakic Pasko
Published: January 2005

The prenatal development of the cortical projections to the dorsal lateral geniculate nucleus (LGN), superior colliculus (SC) and pulvinar was studied by autoradiography of orthogradely transported 3H‐proline injected into the occipital cortex of fetal rhesus monkeys aged from embryonic day 63 (E63) to E95. Differentiation of pyramidal neurons situated in the infragranular strata of the cortical plate (prospective layers 5 and 6, which give rise to these efferent projections) was also examined in Golgi preparations prepared from specimens of corresponding embryonic ages.

In autoradiographs of the E63 fetus, no radioactive label was seen in subcortical structures. In two specimens injected around E70, label was present in the prospective magnocellular layers of the LGN and within the immediately surrounding cell‐poor zones. At these young fetal ages, the presence of topographic order in the corticogeniculate projection could not be determined due to the large size of the injection sites relative to the small cerebral vesicles. By E84 the portion of the prospective parvocellular layers adjacent to the white matter also contained label which was characteristically wedge‐shaped and appropriately located with respect to the site of the cortical injection, suggesting that topographic order is established. In the oldest fetus (E95) label in the LGN assumed a configuration similar to that seen in the adult. The cortical projection also invades the SC and pulvinar around E70. In the SC, label was initially confined to the stratum opticum, but by E84 it extended into the superficial gray. Thus, all known classes of efferent pathways from the visual cortex to subcortical structures are present by the middle of the 165‐day gestational period in rhesus monkey.

The one‐month period, E63–E97, during which these efferent visual connections are established is characterized by the considerable growth and increased complexity of the dendritic arborization of pyramidal cells in the infragranular cortical layers of area 17. Thus the development of visual cortical efferents occurs in rough synchrony with the genesis of the afferent pathway from the LGN (Rakic, '76a; '79) and with the onset of morphological differentiation of pyramidal neurons in the infragranular cortical layers.
Sex differences in dendritic morphology of a song control nucleus in the canary: A quantitative Golgi study
Authors: Devoogd Timothy J. , Nottebohm Fernando
Published: January 2005

Singing in the canary is a learned male behavior controlled predominantly by nuclei in the left hemisphere (Nottebohm and Nottebohm, '76; Nottebohm et al., '76; Nottebohm, '77). These nuclei are several times larger in males than in females (Nottebohm and Arnold, '76). One of the telencephalic song control nuclei, robustus archistriatalis (RA), was examined in Golgi‐stained tissue sections from the left and right hemispheres of male and female canaries. At least four cell classes were present in each sex. One of these cell classes was further studied with a variety of quantitative techniques. No hemispheric differences were seen in either sex. However, dendrites from male cells tend to branch and end further from the cell body than do dendrites from female cells. This differences is seen most clearly when serial sections are used to reconstruct the entire dendritic tree.
Evidence for a catecholaminergic projection to area X in the zebra finch
Authors: Lewis James W. , Ryan Susan M. , Arnold Arthur P. , Butcher Larry L.
Published: January 2005

In the zebra finch (Poephila guttata), horseradish peroxidase injected into or near Area X of the lobus parolfactorius (LPO) is transported to cell bodies in ipsilateral hyperstriatum ventrale pars caudale (HVc), area ventralis of Tsai (AVT), and nucleus tegmenti pedunculo‐pontinus, pars compacta (TPc). Area X, LPO, and paleostriatum augmentatum (PA) all contain a dense network of catecholamine‐containing axons and nerve terminals, as determined in histofluorescence studies. Cell bodies in AVT and TPc contain catecholamines; lesions of TPc greatly reduce or abolish catecholamine fluorescence in PA, and a lesion of AVT eliminates histofluorescence in LPO, including Area X. The anatomical location and catecholaminergic projection from AVT suggest that LPO‐Area X may be the avian homolog of the mammalian nucleus accumbens, olfactory tubercle, and/or rostromedial caudate.
The distribution of commissural terminations in somatosensory areas I and II of the grey squirrel
Authors: Gould Harry J. , Kaas Jon H.
Published: January 2005

The topographic distribution of somesthetic interhemispheric projections was studied in grey squirrels using the Fink‐Heimer technique following large aspiration lesions of the corpus callosum. On the day of perfusion, receptive fields were determined for microelectrode recording sites in the first, S I, and second, S II, somatosensory areas of cortex, and small electrolytic lesions were made in order to identify some of these sites in prepared brain sections. The cortex was then separated from the rest of the brain, flattened, and cut parallel, so that with the aid of the reference lesions, the total pattern of degeneration could be related to a surface view of the brain and to previous electrophysiological maps of S I (Sur et al., '78) and S II (Nelson et al., '79). The results show that callosal terminations are unevenly distributed in S I and S II, and suggest that there are several categories of callosal inputs to S I. A major region of terminations is in the architectonically distinct “unresponsive zone” within SI, and perhaps in other similar, but narrower, specialized zones within and bordering S I, as previously described in rats (Ryugo and Killackey, '75; Wise and Jones, '76, '78; Akers and Killackey, '78). Other callosal projections terminate within the responsive regions of S I. These regions include at least some of the representation of the body midline, most clearly the midline of the representations of the upper and lower face, as well as regions unrelated to the midline of the body. Most or all of the S I cortex responsive to stimuli away from the midline on the upper and lower lips, the mystacial vibrissae, and the glabrous forepaw was almost free of direct callosal terminations. Except for a central core region, most of S II appears to receive a moderate distribution of callosal inputs.
The aberrant retino‐retinal projection during optic nerve regeneration in the frog. II. Anterograde labeling with horseradish peroxidase
Authors: Bohn Ronald C. , Stelzner Dennis J.
Published: January 2005

Previous experiments have shown that a substantial number of regenerating optic axons in adult frogs (Rana pipiens) are misrouted into the opposite optic nerve and retina during early stages of regeneration. This projection is maximal at 5 and 6 weeks after optic nerve crush. To further characterize this anomalous projection, small quantities of horseradish peroxidase (HRP) were injected into the right eye or right optic nerve 5 or 6 weeks after right optic nerve crush. Twenty‐four hours later the animals were killed and regenerating axons anterogradely filled with HRP were reacted with the tetramethyl‐benzidine method or a diaminobenzidine‐CoCl2 method. Serial reconstruction tracing the course of individual axons through the optic chiasm showed that few of the axons projecting into the opposite optic nerve were collaterals of axons projecting centrally. Instead, the majority of labeled axons misdirected into the opposite nerve or contributing to an expanded projection into the ipsilateral optic tract turned out of the chiasm without branching. Many of the labeled regenerating axons had unusual trajectories within the chiasm, making abrupt turns or changing their direction of growth. Most of the axons misrouted into the opposite nerve came from portions of the chiasm nearest to the nerve of the other eye. In three of eight frogs with an intact optic nerve, a small number of HRP‐labeled axons were found in the left nerve after right nerve injection, but there was no indication that these axons reached the left eye. The results from this investigation suggest that the most parsimonious explanation for the chiasmal misrouting of regenerating frog optic axons is that axons are mechanically deflected into inappropriate pathways.
A Golgi study on the globus pallidus of the mouse
Authors: Iwahori Nobuharu , Mizuno Noboru
Published: January 2005

The globus pallidus (GP) of the mouse was studied by the rapid Golgi silver impregnation method. The GP was composed of large and mediumsized neurons. The large neurons had stellate cell bodies with a mean diameter of 25 μm by 28 μm and five to seven primary dendrites. The somato of the mediumsized neurons were spindle or fusiform in shape, measured 19 μm by 27 μm in average and emitted three to five primary dendrites. The large neurons were located mainly in the central part of the GP, whereas the medium‐sized neurons were observed in the peripheral part of the GP. Some GP neurons extended their dendrites into the caudatoputamen complex, sublenticular region or internal capsule. The axons of the GP neurons were seen most frequently to course medially or mediocaudally and to enter the internal capsule or fiber bundles traversing the GP; they were rarely observed to run laterally and to travel into the caudatoputamen complex. Some axons of the GP neurons were also observed to emit intra‐ or extra‐nuclear collaterals extending into the sublenticular region.

Four groups of afferent fibers to the GP were observed; (1) fibers descending within the internal capsule or caudatoputamen complex to terminate or to give axon‐collaterals to the GP; (2) fibers ascending within the internal capsule or fiber bundles traversing the GP to enter the GP from its medial aspects; (3) fibers traversing the internal capsule laterally to terminate in the GP; and (4) fibers running dorsally through the sublenticular region to terminate in the GP. In addition to these four groups of afferent fibers, terminal branches were seen to arise numerously from many fibers running through the GP.
Acetylcholinesterase‐positive fibers and cell bodies in the cochlear nuclei of normal and reeler mutant mice
Authors: Martin Michael R.
Published: January 2005

Sections from the cochlear nuclei of normal and reeler mutant mice were treated by the method of Karnovsky and Roots ('64) for the demonstration of cholinesterase activity. In one group of controls ethopropazine was used to inhibit pseudocholinesterases and in another group BW 284C 51 was used to inhibit acetylcholinesterase (AChE). The distribution of AChE‐positive fibers in the normal mouse is given. The reeler mutant mouse differs from the normal in that there are no AChE‐positive fibers in the dorsal nucleus, very few in the granule cell layer separating the dorsal from ventral nuclei, none in the granule cell layer covering the lateral aspect of the ventral nucleus, and the number in the posteroventral and caudal anteroventral nuclei are greatly reduced. Perisomatic terminals, small and large terminal boutons, and boutons en passant are present in both normal and reeler mutant mice. AChE‐positive cell bodies are found in the deep region of the dorsal nucleus, the rostral part of the posteroventral nucleus, and the anteroventral nuclueus of both normal and reeler mutant mice. The observations in the normal mouse are compared to the distribution of AChE‐positive fibers and the types of terminals formed by noncochlear afferents in other species. Several possible causes of the lesion of the AChE‐positive fibers in the reeler mutant mouse are considered.
Cytology and synaptology of the lateral reticular nucleus of the cat
Authors: Hrycyshyn A. W. , Flumerfelt B. A.
Published: January 2005

The organization of the lateral reticular nucleus (LRN) of the cat was investigated using electron microscopic and Golgi techniques. Golgi‐Cox preparations revealed that the LRN consists of allodendritic and, especially, isodendritic neurons. The latter have been associated with neural centres that have important roles integrating signals from distant sources. Several froms of spines were identified with the Golgi method, and their ultrastructural correlates were determined. Somatic spines resembled stubby protrusions, while dendritic spines, which were usually observed on distal dendrites, appeared as pedunculated spines, recemose appendages and spine‐crowned appendages.

Ultrastructural exmaination of this nucleus revealed various synaptic relationships. The majority of the synaptic terminals were small (1.5–2.5 μm in diameter), contained round vesicles and usually contacted dendrites and spines. Other small terminals contained pleomorphic vesicles and contacted distal dendrites and spines. Large terminals (>2.5 μm in diameter) with round or pleomorphic vesicles contacted the somata or proximal dendrites. Three types of “synaptic configurations,” which consisted of discrete aggregations of neuronal processes invested by astrocytic lamellae, were also identified. These structural arrangements likely provide a basis for the integration of inputs to the LRN from spinal and supraspinal centres.
Neuronal and synaptic structure of the dorsal lateral geniculate nucleus in normal and monocularly deprived Macaca monkeys
Authors: Wilson James R. , Hendrickson Anita E.
Published: January 2005

The dorsal lateral geniculate nucleus (dLGN) of Macaca monkeys was studied by Golgi and quantitative electron microscopic (EM) methods to determine if differences in neuronal morphology exist which might correlate with the known physiological separation of X‐type cells into the parvocellular and Y‐type cells into the magnocellular laminae. Monocularly lid‐sutured Macaca monkeys were also studied by quantitative EM methods to compare the synaptic organization within laminae innervated by the deprived and nondeprived retinae.

We have divided our sample of Golgi‐impregnated neurons into three groups: Types A, B, and C. Type A neurons comprise the majority of the projection cells and are quite heterogeneous in their overall morphology. Type B neurons have long dendrites with multiple appendages; some have a locally ramifying beaded axon. Type C neurons are characterized by dendrites which are mainly restricted to the interlaminar zones. We found Type A and B neurons in both the parvocellular and magnocellular laminae. The cell bodies of Type C neurons lay within the interlaminar zones or the parvocellular laminae. All three types contributed dendrites to the interlaminar zones. No significant differences in Golgi morphology other than overall size were found in parvocellular or magnocellular laminae that would explain the previously demonstrated electrophysiological differences.

Terminal profiles and synapses in the parvocellular, magnocellular, and interlaminar zones were classified and counted using quantitative EM methods. RSD and F terminals were most numerous in all three zones. RLP terminals were rare in the interlaminar zones. A new type of terminal, RMD, was found in the magnocellular interlaminar zones. The laminar and interlaminar zones have the same overall synaptic density, but differed in types of synaptic terminals. The only quantitative difference between any of these regions was in the magnocellular laminae where the counts showed 70% more F terminals per unit area.

The same quantitative methods were applied to the laminar and interlaminar zones of dLGNs from monocularly lid‐sutured monkeys. We found no qualitative or quantitative difference between the synaptology of zones receiving input from the deprived retina compared to the open eye retina, nor between any regions of the dLGN in deprived monkeys compared to normal monkeys.
Neuronal organization of the rabbit cochlear nucleus: Some anatomical and electrophysiological observations
Authors: Perry Dennis R. , Webster William R.
Published: January 2005

The cochlear nucleus of the young adult rabbit was studied using both anatomical and electrophysiological techniques. The cytoarchitecture of the cochlear nucleus, as revealed by Nissl‐staining and Bodian's Protargol method, was quite similar to that of the cat. The cell types observed by the Golgi‐Cox method were very similar to those observed in the cat cochlear nucleus. Bushy and stellate cells were predominant in the anterior ventral cochlear nucleus, and multipolar and globular cells were observed throughout the posterior ventral cochlear nucleus, surrounding a region containing mainly octopus cells. The dorsal cochlear nucleus was revealed as a laminated structure with a prominent band of fusiform cells. The polymorphic layers contained varieties of giant neurons similar to those observed in the cat. Units in the cochlear nucleus were classified electrophysiologically, in terms of their discharge pattern, and located histologically. The ventral cochlear nucleus contained mainly “primarylike,” “chopper” and “onset” units, but the dorsal cochlear nucleus contained a greater variety of response patterns. “Buildup,” “pauser” and “chopper” response patterns were predominant, and the dorsal cochlear nucleus also contained more inhibitory units than the ventral cochlear nucleus.

Both the types of units observed and their location in each nucleus were very similar to those reported for the cat. Both divisions of the ventral cochlear nucleus and the dorsal cochlear nucleus were found to be tonotopically organized in a dorsal (high frequency) to ventral (low frequency) direction. A trend for an organization in a medial to lateral direction was also apparent, particularly in the dorsal cochlear nucleus.
Morphological analysis of astrocytes in the bullfrog (Rana catesbeiana) spinal cord with special reference to the site of attachment of their processes
Authors: Sasaki Hiroshi , Mannen Hajime
Published: January 2005

An attempt was made to elucidate the morphological reatures of astrocytes in the bullfrog spinal cord by means of a combination of electron microscopy, the Golgi method, and the intravascular dye injection method.

Astrocytic somata are densely concentrated both in the wall of the central canal and in its proximity, and diffusely distributed in the intermediate and the ventral part of the gray matter. The most complicated and densest vascular network is found in the dorsal part of the gray matter. There is little correlation between the density of the distribution of astrocytic somata and that of the vascular network.

Each astrocyte emits one process and ramifies by repeated bifurcations as it approaches the white matter or enters it. All these branching processes reach the pial surface of the spinal cord (the principal processes). Total rostrocaudal extent of their ramification is within 400 μm. A great number of small lateral offshoots (the secondary processes) arise both from the somata and the principal processes.

Electron microscopy of vessel walls and the pial surface revealed that the principal processes attach to the subpial basement membrane with a specialized structure, an electron‐dense layer, while the secondary processes merely surround blood vessels in a mode of juxtaposition.

Comparison between amphibian and mammalian astrocytes is made regarding the site of attachment of their processes.
Development of chorda tympani taste responses in rat
Authors: Ferrell M. F. , Mistretta C. M. , Bradley R. M.
Published: January 2005

To learn whether neurophysiological taste responses change during structural development of the gustatory system, we recorded from the chorda tympani nerve in rats aged 7 to 92 days after birth. Chemical stimuli applied to the anterior tongue included four monochloride salts, two acids, sucrose, and urea. Responses to all chemicals were obtained as early as 7 days postnatally. Developmental changes in salt, acid, and sucrose responses were observed. Relative to NaCl and LiCl, NH4Cl and KCl gradually decrease in effectiveness as taste stimuli; or, relative to NH4Cl and KCl, NaCl and LiCl become more effective stimuli. These changes are similar to those observed prenatally and postnatally in sheep. Also, relative to NaCl, citric acid, hydrochloric acid, and sucrose become less effective stimuli; or, NaCl becomes more effective as a stimulus, relative to these acids and sucrose. The period of most rapid functional change overlaps a period of rapid structural change. It seems most reasonable to hypothesize that the altering taste responses reflect developmental changes in receptor membrane composition. Since the taste system is not programmed to respond in a mature manner from the moment function begins, there is ample opportunity for changing taste experience to influence the developing taste system.
Direct and indirect pathways from the amygdala to the frontal lobe in rhesus monkeys
Authors: Porrino L. J. , Crane A. M. , Goldman‐Rakic P. S.
Published: January 2005

To elucidate the anatomical relationships between the frontal association cortex and the limbic system in primates, projections from the amygdala to frontal cortex were studied in the rhesus monkey using retrograde and anterograde tracing methods. Following injections of horseradish peroxidase (HRP) into the orbital prefrontal cortex, the gyrus rectus, the superior frontal gyrus, and the anterior cingulate gyrus of the frontal lobe, labeled neurons were found in the basolateral, basomedial, or basal accessory nuclei of the amygdala. None of these nuclei contained labeled neurons following HRP injections into the principal sulcus or the lateral inferior convexity of the frontal lobe. This selective distribution of amygdala connections was confirmed by injecting tritiated amino acids into the amygdala. Silver grains were present only over the orbital cortex and gyrus rectus on the ventral surface of the frontal lobe and over the superior prefrontal gyrus and anterior cingulate gyrus on the medial wall of the hemisphere, while the dorsolateral prefrontal cortex was free of radioactivity. The isotope injection of the amygdala also revealed a projection to the magnocellular moeity of the mediodorsal nucleus (MDmc) which is known to innervate the same ventromedial regions of the frontal lobe that receive direct connections from the amygdala. Although MDmc and amygdala project to the same cortical regions, their terminal fields are different. The direct amygdala input terminates in layer 1 in orbital cortex and gyrus rectus and layer 2 in the dorsomedial cortex and cingulate gyrus, while the thalamic input is primarily to layer 3 and, in some areas, also to the superficial half of layer 1.

These findings indicate that the frontal lobe of rhesus monkeys can be subdivided into two separable cortical regions:(1) A ventromedial region including the anterior cingulate gyrus which receives both direct (amygdalo‐cortical) and indirect (amygdalo‐thalamo‐cortical) input from the amygdala; and (2) a dorsolateral frontal region which is essentially devoid of either direct or indirect amygdalofugal axons. On the basis of its selective relationship with the amygdala, the ventromedial region may be considered the “limbic” portion of the frontal association cortex.
A morphological study of cat dorsal spinocerebellar tract neurons after intracellular injection of horseradish peroxidase
Authors: Randić M. , Miletić V. , Loewy A. D.
Published: January 2005

This work represents an attempt to elucidate structural features of electrophysiologically characterized, individual cat dorsal spinocerebellar tract (DSCT) neurons by using intracellular application of horseradish peroxidase (HRP).

Intracellular recordings and HRP injections were made in DSCT neurons of the Clarke's column in cat lumbar (L3) spinal cord. The units were identified by antidromic invasion following electrical stimulation of the ipsilateral dorsolateral funiculus at C1. In addition, sensory inputs to the DSCT neurons were determined by natural (adequate) stimuli applied to the hind limb with intact innervation.

The morphological analysis is based on data obtained from 19 well‐stained electrophysiologically identified neurons located in Clarke's column. Thirteen of these units received excitatory sensory inputs from muscle receptors, two were activated by cutaneous afferents only, and four had a convergent (muscle + cutaneous) input. The DSCT‐muscle cells were equivalent to the large Clarke cells (class C of Loewy, '70). Their dendrites were oriented primarily in the rostrocaudal direction (up to 2500 μm) and appeared generally smooth except for some branchlets. In four of these cells, the axon was traced into the lateral funiculus. In light microscopic analysis there was no evidence that axon collaterals arose from these axons during the initial trajectory through the spinal grey matter. The four DSCT‐convergent neurons were similar in shape to the DSCT‐muscle units although they appeared to have somewhat smaller cell bodies. Of the two DSCT‐cutaneous neurons one was found to be of the B type, with the dendritic tree having fewer branches and oriented mainly in the medio‐lateral direction. The other cell, however, turned out to be similar in appearance to the C type Clarke neurons.