bluuebunny/crossref_metadata_2025 huggingface dataset:
Striatal neurons containing both somatostatin‐ and avian pancreatic polypeptide (APP)‐like immunoreactivities and NADPH‐diaphorase activity: A light and electron microscopic study
Authors: Vincent Steven R. , Johansson Olle
Published: January 2005

Striatal neurons containing both somatostatin‐ and avian pancreatic polypeptide (APP)‐like immunoreactivities have been shown to be selectively stained by the histochemical method for nicotinamide adenine dinucleotide phosphate (NADPH)‐diaphorase activity. In the present study, we have utilized this histochemical technique to examine the morphology of these Striatal neurons at the light and electron microscopic levels. Our results indicate that the Striatal somatostatin/APP/NADPH‐diaphorase neurons occur throughout the striatum and have long, aspiny dendrites, oval, invaginated nuclei with prominent nucleoli, and receive few axosomatic contacts. These cells appear to correspond to a population of medium‐sized aspiny interneurons reported previously in Golgi and electron microscopic studies of the striatum.
Subdivisions of the inferior colliculus in the barn owl (Tyto alba)
Authors: Knudsen Eric I.
Published: January 2005

The inferior colliculus in the barn owl contains three subdivisions: the central (ICC), external (1CX), and superficial (ICS) nuclei. The nuclei are distinguished on the basis of their cyto‐ and myeloarchitecture, connectivity, and physiological properties. The ICC may be further divided into dorsal (ICCd) and ventral (ICCv) parts. Auditory fibers ascending in the lateral lemniscus enter the ICCd and ICCv, but not the ICX or ICS. The ICX receives its auditory input from the ICC. The ICC and ICX in owls are similar in position, anatomy, connectivity, and physiology to the ICC and ICX in mammals, suggesting that these structures are homologous. Units in the ICC are organized to potopically, whereas units in the ICX are organized according to the locationns of their spatial receptive fields. This implies that a transformation from tonotopic to a spatiotopic organization takes place in the ICX of the owl.
The perihypoglossal nuclei in the macaque monkey and thechimpanzee
Authors: Brodal A.
Published: January 2005

The topography of the perihypoglossal nuclei (nucleus intercalatus, nucleus prepositus, and nucleus of Roller) of the macaque and the chimpanzee was studied in serial Nissl‐stained sections through the brainstem. Maps of the nuclei in the two species are presented.

Although in both species the perihypoglossal nuclei are organized according to the general mammalian pattern, they show some particular features, reflecting in part, an increasing phylogenetic differentiation. In the chimpanzee the nucleus prepositus is relatively larger, the nucleus of Roller is more of a separate unit, and its cellular composition is more uniform than is the case in the macaque. A cellular connection between the two nuclei is present in the macaque (even more conspicuous in the cat, apparently absent in man), but is barely discernible in the chimpanzee. A conspicuous difference between the chimpanzee and the macaque concerns the nucleus supra‐genualis nervi facialis, forming a rostral continuation of the prepositus. In the chimpanzee it is a loosely structured region of small cells (as in the cat and in man). In the macaque, however, it appears as a rather well‐delimited column of chiefly medium‐sized cells.

Some comparative anatomical and functional aspects are discussed. Many contingents of afferents to ‐ and efferents from – the nucleus preposi tus have their preferential sites of termination or origin in the nucleus, although with considerable overlapping. This indicates the presence of topical patterns in the prepositus. In general the caudal parts appear to be more related to the cooperation with the cerebellum than the rostral part, whereas the latter appears to be more particularly linked with the oculomotor apparatus.
Death of motorneurons during the postnatal loss of polyneuronal innervation of rat muscles
Authors: Bennett M. R. , McGrath P. A. , Davey D. F. , Hutchinson I.
Published: January 2005

A study was made of the decline in the number of motor neurons and axons of the brachial spinal cord of the rat during postnatal development. The injection of horseradish perodidase (HRP) into the biceps muscle showed that it was innervated by motor neurons located in the dordolateral position of the lateral mototr coluimn in segments C5 and C6; HRP injections into the triceps muscle showed that it was innervated by mototr neurons located in the ventrolateral posotion of the lateral motor coumn in segments C7 and C8. There was no change in the position of these motor neurons pools between birth and maturity, However, these was a decline in the number of neurons in each pool during the postnatal period; over 35% of the neurons presents at birth had disappeared by maturity. This loose of neurons was uniform throughout the restrocaudal extent of each pool. It was accompanied by a similar percentage loss in the number of axons in a ventral root at the brachial level (C8). Electrophjysiological measurements showed that the disappearance of motor neurons was accompanied by a loss in the polyneuronal innervation of synaptic sites in the biceps muscle. The possibility that a decrease in the number of neurons contributes to the loss of polyneorunal innervation is discussed.
Neuronal subpopulations in cat retina which accumulate the GABA agonist, (3H)muscimol: A combined Golgi and autoradiographic study
Authors: Pourcho Roberta G. , Goebel Dennis J.
Published: January 2005

Golgi impregnation techniques were combined with, electron microscopic autoradiography of (3H)muscimol in order to provide morphological identification of labeled neurons in the cat retina. This γ‐aminobutyric acid (GABA) agonist has been shown to label the same neurons which accumulate (3H)GABA. Selected cells were photographed and drawn by the aid of a camera lucida drawing tube prior to being thin sectioned for autoradiography.

The (3H)muscimol‐accumulating neurons which were identified include an interplexiform cell, five classes of conventional amacrine cell, and another cell with its soma located in the ganglion cell layer which is either a ganglion cell or a displaced amacrine. The conventional amacrine cells were compared with the recent morphological classification of Kolb et al. (Vision Res. 21: 1081‐1114, '81) and identified as A2, A10, A13, A17, and A19 amacrine cells. These cells exhibit a widespread distribution providing input to all five strata of the inner plexiform layer.
Fetal development of primate chemosensory corpuscles. II. Synaptic relationships in early gestation
Authors: Zahm Daniel S. , Munger Bryce L.
Published: January 2005

Fungiform papillae contained well‐developed chemosensory corpuscles in macaque monkey fetuses with crown‐rump lengths of 5.0‐9.0 cm. These fetuses corresponded to stages from the last part of the first and beginning of the second trimester of gestation. Chemosensory cells extended from the epithelial basal lamina to the taste pore anlage at the apex of the corpuscle and had typical afferent synaptic contacts with presumptive gustatory axons. Apical secretory granules, the distinctive cytologic feature of sustentacular cells, were absent. Cells with cytologic characteristics intermediate between chemosensory cells and basal extragemmal cells were considered to be differentiating chemosensory (DC) cells and appeared to arise from existing basal cells as well as undifferentiated postmitotic cells. Although extragemmal cells were extensively coupled by gap junctions which are apparent in electron micrographs of thin sections, similar junctions were absent from chemosensory and DC cells. While having minimal structural requirements for transduction and transmission of sapid stimuli (i.e., an intraoral surface and afferent synaptic contacts) chemosensory cells lacked efferent synapses and subsurface cisternae, which can be observed at later stages of gestation. Axoaxonic synapses, present between gustatory axons in the intragemmal and extragemmal epithelium and in the subgemmal connective tissue, were observed with greater frequency than at later stages of gestation. We conclude that the differentiation of chemosensory cells precedes the differentiation of sustentacular cells by several weeks. This fact lends support to the concept that chemosensory cells are a unique identifiable cell type in all chemosensory corpuscles.
Morphology of cat phrenic motoneurons as revealed by intracellular injection of horseradish peroxidase
Authors: Cameron W. E. , Averill D. B. , Berger A. J.
Published: January 2005

The morphology of phrenic motoneurons (PMs) of adult cat was examined by utilizing the technique of intracellular injection of horseradish peroxidase. Twenty‐one cells were reconstructed from serial sections in transverse, sagittal, and horizontal planes. The cell bodies were ellipsoid, with the major diameter oriented parallel to the longitudinal axis of the spinal cord.

The dendrites of PMs are not distributed in a radially symmetric fashion, but rather project to four separate fields. The field containing the greatest number of dendrites extends rostrocaudally within the phrenic motor column. This collection of dendrites forms a rostrocaudal bundle in which the dendrites from neighboring PMs lie in close association with one another. The remaining dendrites project dorsolaterally, dorsomedially, and to a lesser extent, ventrally. The dorsolaterally directed dendrites form bundles upon entering the lateral funiculus with the dendrites from other PMs. Several of the dorsomedially directed dendrites cross to the contralateral spinal cord via the anterior commissure or central gray. A wide variety of dendritic spines and appendages was observed.

There were no instances in which axon collaterals were observed for the 11 well‐stained axons examined. The length of the initial segment of the axon was a function of the distance of the cell body from the ventral funiculus.
Posterior lateral line afferent and efferent pathways within the central nervous system of the goldfish with special reference to the Mauthner cell
Authors: Zottoli Steven J. , Van Horne Craig
Published: January 2005

The goldfish posterior lateral line nerve consists of a dorsal and a ventral branch, each of which is associated with a ramus of the sensory branch of the VII th nerve (ramus recurrens facialis). The afferent and efferent pathways of these nerves within the central nervous system were studied by using horseradish peroxidase (HRP) histochemistry.

The afferent fibers of the ramus recurrens facialis travel in the ventral portion of the VIIth nerve as it enters the brain and project predominantly to the ipsilateral half of the facial lobe.

The afferent fibers of either the dorsal or ventral branch of the posterior lateral line nerve split into two bundles as they enter the brain. The caudally projectingfascicle terminates predominantly in thenucleusmedialis. The fibers of the rostrally projecting bundle terminate predominantly in nucleus medialis and nucleus magnocellularis and in the eminentia granularis.

The posterior lateral line efferent somata were located in the diencephalon as well as in the medulla oblongata. The medullary efferent neurons formed two distinct groups, a rostral and a caudal nucleus. The cell bodies of the latter were more numerous and larger than those of the former. The axons of the efferent neurons exit from the brain by one of two routes. The first is at the level of the rostral efferent nucleus and the second at the level of the Mauthner cell.

Previous reports have described input of posterior lateral line afferent fibers to the Mauthner cell soma and proximal lateral dendrite of the goldfish. This electrophysiological input was bilateral and was interpreted as monosynaptic. The afferent input described in this study was ipsilateral and ended in the vicinity of the distal lateral dendrite. These differences are discussed in the context of the neuronal circuitry that may be present.
The dual origins of the olivocochlear bundle in the albino rat
Authors: White James S. , Warr Bruce W.
Published: January 2005

Recent studies of the origins and terminations of the olivocochlear bundle (OCB) in the cat provide evidence that separate efferent systems differentially innervate the two types of hair cells in the organ of Corti. To begin to test the generality of these separate olivocochlear systems, the cells of origin of the OCB were determined in the albino rat by using axonal transport of horseradish peroxidase. Our findings are that, as in the cat, two classes of olivocochlear (OC) neurons project to the cochlea. These neurons could be dichotomized according to their location in the superior olivary complex (lateral or medial), their size (small or large), and their preferred side of projection (ipsilateral or contralateral). All labeled OC neurons also exhibited a positive reaction for acetylcholinesterase. In the rat, however, lateral and medial OC neurons are each restricted to a single nucleus, and, furthermore, the lateral OC neurons project only ipsilaterally. The rat also has significantly fewer mean totals of both lateral (240vs. 710)and medial (240 vs. 520) OC neurons than the cat. The present methods also demonstrated the course of axons of the OCB and axon collaterals entering the cochlear nuclear complex. Vestibular efferent neurons were also labeled bilaterally medial and lateral to the facial genu. Our results suggest that the general organizational plan of OC neurons in the rat may offer advantages over the situation in the cat for studies of connectional neuroanatomy, neurophysiology, and behavioral functions of the two olivocochlear systems.
The distribution of serotonin in the CNS of an elasmobranch fish: Immunocytochemical and biochemical studies in the atlantic stingray, Dasyatis sabina
Authors: Ritchie T. C. , Livingston C. A. , Hughes M. G. , McAdoo D. J. , Leonard R. B.
Published: January 2005

The distribution of serotonin (5HT) in the brain of the Atlantic stingray was studied with peroxidase‐antiperoxidase immunocytochemistry and high‐pressure liquid chromatography. The regional concentrations of 5HT determined for this stingray fell within the range of values previously reported for fishes. A consistent trend in vertebrates for the hypothalamus and midbrain to have the highest concentrations and the cerebellum the lowest was confirmed in stingrays. Neuronal cell bodies and processes exhibiting 5HT‐like immunoreactivity were distributed in variable densities throughout the neuraxis. Ten groups of 5HT cells were described: (I) spinal cord, (II‐IV) rhombencephalon, (V, VI) mesencephalon, (VII, VIII) prosen‐cephalon, (IX) pituitary, and (X) retina. There were three noteworthy features of the 5HT system in the Atlantic stingray: (1) 5HT cells were demonstrated in virtually every location in which 5HT‐containing cells have been described or alluded to in the previous literature. The demonstration of immunopositive cells in the spinal cord, the retina, and the pars distalis of the pituitary suggests that 5HT may be an intrinsic neurotransmitter (or hormone) in these regions. (2) The distribution of 5HT cells in the brainstem shared many similarities with that in other vertebrates. However, there were many 5HT cells outside of the raphe nuclei, in the lateral tegmentum. It appears that the hypothesis that “lateralization” of the 5HT system is an advanced evolutionary trend cannot be supported. (3) 5HT fibers and terminals were more widely distributed in the Atlantic stingray brain than has been reported for other nonmammalian vertebrates on the basis of histofluorescence. It appears that this feature of the 5HT system arose early in phylogeny, and that the use of immunohistochemistry might reveal a more general occurrence of widespread 5HT fibers and terminals.
Fine structure of dividing astroglia and oligodendroglia during myelin formation in the developing mouse spinal cord
Authors: Meinecke Douglas L. , de F. Webster Henry
Published: January 2005

To study the morphology and cellular relationships of dividing glial cells during myelin formation, we perfused newborn and 5‐day mouse pups and embedded slices of cervical, thoracic, and lumbar cord for light and electron microscopic study. In semithin epon sections stained with toluidine blue, all levels of spinal cord at both ages contained mitotic glia in gray columns and funiculi. In electron micrographs of funiculi, dividing astroglia contained bundles of glial filaments, many glycogen granules, and had large processes extending into the surrounding neuropil. Cytoplasmic organelles of many immature interphase oligodendroglia and mitotic oligodendroblasts were similar and included microtubules, clusters of free ribosomes, and scattered profiles of granular endoplasmic reticulum. Unlike astroglia, dividing oligodendroblasts lacked large processes and in metaphase they were ellipsoids and had smooth plasma membranes. When these cells were studied in alternating serial thin and semithin sections over 10–15‐μm distances, we did not identify connections between myelin sheaths and mitotic oligodendroblasts. Our findings indicate that oligodendroglia in developing white matter multiply before developing large processes. Our data also suggest that oligodendroglia do not divide while forming myelin.
Light and electron microscopic studies of the basilar papilla in the duck, Anas platyrhynchos. I. The hatchling
Authors: Chandler John P.
Published: January 2005

The intent of this study was to describe in detail the normal structure of the basilar papilla in the duck, Anas platyrhynchos, with light and electron microscopy. The cochlear duct is supported by a ring of dense periotic connective tissue, the limbus. Distribution of hair cells in the basilar papilla follows the general avian pattern. Tall hair cells occupy the neural margin of the papilla. Short hair cells cover the abneural margin from the proximal tip to the middistal area. Intermediate hair cells form a transition zone from genu to distal tip. Patterns of innervation are correlated with hair cell morphology, which supports the classification of hair cells in birds into three groups. Tall hair cells synapse with two to four large afferents and one efferent; intermediate hair cells synapse with one or two afferents and one or two efferents; short hair cells synapse with one small afferent and one or two large efferents. In this relatively primitive species of bird, cuticles in all classes of hair cells reach the plasmalemma on the neural side of the cell, a condition that supports the contention that tall hair cells are more primitive than short hair cells.
Acetylcholinesterase activity in the sexually dimorphic area of the gerbil brain: Sex differences and influences of adult gonadal steroids
Authors: Commins Deborah , Yahr Pauline
Published: January 2005

The morphology of the medial preoptic area‐anterior hypothalamus (MPOA‐AH) of gerbils is sexually dimorphic and influenced by adult gonadal hormones. This research shows that the distribution of (MPOA‐AH) cells that synthesize acetylcholinesterase (AChE) and the activity of AChE within the MPOA‐AH are also sexually dimorphic and hormone sensitive. Adult male and female gerbils were gonadectomized, gonadectomized and implanted subcutaneously with testosterone (T), or sham operated 4–8 weeks before sacrifice. Coronal sections through the sexually dimorphic area (SDA) of the MPOA‐AH were stained for AChE. Planimeter measurements of camera lucida drawings showed that the total volume of the SDA is similar in the two sexes, but the proportion of the SDA that stains darkly and/or stands out clearly from the surround (dark volume) is larger in males. Optical density readings also indicated that AChE staining is darker in the male SDA. Gonadectomy decreases staining intensity in both sexes and reduces total SDA volume. Dark volume decreases more than 50%. Testosterone treatment reverses all effects of gonadectomy, although hormonal influences are smaller in females than in males. There were no sex differences or hormonal influences on AChE staining lateral to the SDA. The pars compacta of the male SDA was essentially devoid of AChE, indicating that this cell group is distinct from the rest of the SDA. It also shrinks after castration unless the males receive T. Histochemical changes in the SDA may be related to hormonal control of scent marking, a form of communication in this species.
Motoneuron death after sciatic nerve section in newborn rats
Authors: Schmalbruch Henning
Published: January 2005

When the sciatic nerve was cut in newborn rats almost all of the motoneurons were subsequently lost. The adult sciatic nerve contained 7,640 myelinated fibers of which 1,650 were motor axons. The ventral roots of the sciatic nerve (L4‐L6) contained in all 4,080 myelinated fibres; only 2,380 were present 5–30 weeks after the sciatic nerve had been cut at birth. The deficit of 1,700 fibres corresponded to the number of motor axons in the sciatic nerve. The motoneuron pools were depleted and practically no labelled or unlabelled perikarya were after found after HRP had been applied to the nerve proximal to the former lesion. The deficit of ventral root fibres was 1,030 when the nerve had been cut at age 1 week; nerve section 4 weeks after birth was not followed by retrograde loss of motor axons. Nerve crush at birth caused a deficit of 1,230 ventral root fibres. The incomplete loss of motor axons after crushing was due to the fact that not all axons had been severed.

The continuity of the nerves cut at birth was always restored and myelinated axons which probably were dorsal root ganglion afferents grew into the atrophic muscles. Roughly two‐thirds of the myelinated sensory fibres degenerated after axotomy at birth. The denervated muscle fibres were not reinnervated but vanished eventually and were replaced by fat cells.
Embryonic development of monoaminergic neurons in the chick retina
Authors: Kato S. , Negishi K. , Teranishi T.
Published: January 2005

By means of a histofluorescence technique, embryonic and postnatal development of monoaminergic neurons was followed in the chicken retina with or without intravitreal injection of monoamines 30–60 minutes before eye removal. Fluorescent cells were tentatively classified into five subsets with respect to the soma shape, localization, migration of somata during retinal development, uptake capacity (color and intensity in fluorescence), and sensitivity to neurotoxins. The five subsets of cells were endogenous dopaminergic (DA), catecholamine‐accumulating (CA), indoleamine‐accumulating (IA), CA‐bipolarlike, and IA‐bipolarlike cells. Greenish endogenous DA‐cells first appeared at the 14–15th embryonic day. The cell body of DA‐cells was initially fusiform and located slightly distal to the innermost level of the inner nuclear layer (INL). They became round or oval and migrated to the innermost level of the INL by day 20. Both large and small bottle‐shaped CA‐cells were visualized at an intermediate portion of INL by intravitreal injection of exogenously applied dopamine or noradrenaline (1–2 m̈g/eye) at day 10. Large bottle‐shaped cells, like the DA cells, changed to round or oval and migrated to the innermost level of the INL by day 20. On the other hand, small bottle‐shaped CA‐cells retained their cell shape and location in the INL as retinal development progressed. Therefore, the large bottle‐shaped CA‐cells seen in an early developmental stage correspond to the DA‐cells. IA‐cells were visualized one or two cell rows outward in the INL first at day 13–14 by intravitreal injection of 5,6‐dihydroxytryptamine or 5‐hydroxytryptamine (1–5 m̈g). These cells did not change their relative location during development. The emergence of the catecholaminergic uptake property (DA‐ and CA‐cells) may slightly precede that of the indoleaminergic property (IA‐cells) in the embryonic stage. When excess doses (10–20 m̈g) of monoamines were intravitreally injected, a large number of CA‐ and IA‐bipolarlike cells became visible, peaking in number probably during a certain embryonic period (after day 14–15). DA‐ and CA‐cells could be destroyed by intravitreal injection of 6‐hydroxydopamine (15 m̈g, twice) and IA‐cells could be selectively eliminated by intravitreal 5,7‐dihydroxytryptamine, whereas CA‐ and IA‐bipolarlike cells were not influenced by the dose of neurotoxins used.
Diencephalic connections of the raphé nuclei of the rat brainstem: An anatomical study with reference to the somatosensory system
Authors: Peschanski Marc , Besson Jean‐Marie
Published: January 2005

The present study was undertaken to analyse in detail the connections of the various raphé nuclei with thalamic structures. Micropipettes filled with an aqueous solution of wheat‐germ agglutinin conjugated to horseradish peroxidase were used to produce small iontophoretic deposits restricted to the various raphé nuclei in male Sprague Dawley albino rats. Tetramethyl benzidine was used as a chromogen to reveal both fiber terminals anterogradely labeled and retrogradely filled neurons. A detailed discussion of the possible cases of artefactual labeling using this technique is given.

The present study confirms the results obtained previously in the cat that indicate that the various raphé nuclei project to different areas of the diencephalons. Related to the somatosensory system, the B3area (nucleus raphé magnus) projects to the nucleus submedius and anterior intralaminar nuclei know to receive spinothalamic inputs, but not to the ventrobasal complex. The distribution of afferents from this nucleus suggests an innervation primarily of thalamic structures involved in the somatosensory system. The nucleus raphé medianus projects to the rentrobasal complex and the nucleus submedius, but the fact that its projections are widespread, including all thalamic sensory „relay”︁ nuclei and the entire nucleus reticularis thalami, suggests that it could participate in a „nonspecific”︁ system of control of different sensory modalities. The nucleus raphé dorsalis generally does not project to the thalamic nuclei believed to the involved in the somatosensory system.
Co‐localization of retrogradely transported wheat germ agglutinin and the putative neurotransmitter substance P within trigeminal ganglion cells projecting to cat middle cerebral artery
Authors: Liu‐Chen Lee‐Yuan , Gillespie Steven A. , Norregaard Thorkild V. , Moskowitz Michael A.
Published: January 2005

Neurons containing both wheat germ agglutinin (WGA) and substance P (SP) immunoreactivities were found in the ophthalamic division of the ipsilateral trigeminal ganglia following application of the axonally transported lectin WGA to cat middle cerebral artery. Immunohistochemistry was accomplished by staining for WGA and SP on adjacent sections by using the chromogen diaminobenzidine, or by staining on a single section with sequential application of WGA and SP antisera using the chromogens diaminobenzidine and 4‐chloro‐1‐naphthol, respectively. These observations confirm the results of trigeminal lesion studies indicating that trigemino‐vascular projections to the middle cerebral artery in the cat contain the neurotransmitter SP. In addition, other neurotransmitters may be present in this pathway since less than 50% of WGA‐labeled cells contained SP.
A Golgi study of the development of the inferior olivary nuclear complex in the chicken
Authors: Furber Susan E.
Published: January 2005

The present study is an examination of the qualitative and quantitative changes in the morphology of neurons in the inferior olivary nuclear complex (IOC) of the chicken. The development of the chicken IOC was studied with the Golgi technique between embryonic day 11 (E11) and posthatch day 35 (P35). The olivary cells change most between E11 and E19 and are essentially mature (i.e., similar to P35) at E19. These changes chiefly involve a gradual loss of features that typify immature growing cells (e.g., growth cones, growth buds, filopodia, beaded dendrites); from E11 to P35 there is an increase in the soma size by 42%, an increase in the dendritic field size by 49%, and a decrease in the number of dendritic branches by 47%. A minor but significant fall in the number of dendrites per neuron between E11 and E19 was observed, but as there is no significant difference between E11 and P35, the relevance of this observed change, if any, is unclear.

On the basis of dendritic branching, it appears that one type of olivary neuron is present in the chicken, which is similar to the type of neuron found in the caudal medial olive (MO) and the caudal dorsal olive (DO) of mammals (Schiebel and Schiebel, ′55; Rutherford and Gwyn, ′80). This finding correlates with the proposal that the avian IOC corresponds mostly to the mammalian MO and DO and that only a small portion corresponds to the mammalian principal olive (Furber, ′83).
The insular formations of the dolphin brain: Quantitative cytoarchitectonic studies of the insular component of the limbic lobe
Authors: Jacobs Myron S. , Galaburda Albert M. , McFarland Willard L. , Morgane Peter J.
Published: January 2005

The large insula of the bottlenose dolphin consists of radial gyri arising, in fanlike fashion, from the transverse insular gyrus, and is covered completely by the frontal, parietal, and temporal opercula. On cytoarchitectonic grounds, the dolphin insula is divided into anterior, middle, and posterior sectors that may be the equivalent of the three similar sectors present in the primate insula. Rostrocaudally, these sectors become increasingly more homogeneous and less laminated. Within each sector progressive differentiation occurs in the direction of the circular sulcus. A transitional cortex, the peripaleocortex in the transverse insular gyrus, is interposed between the prepiriform and the periamygdalar cortex and the proisocortex of the insula proper. This peripaleocortex consists of outer and inner cellular strata separated by a hypocellular lamina dissecans. The outer cell stratum is continuous with layers II and III of the insular proisocortex; the more prominent inner stratum is continuous with proisocortical layers V and VI; the intervening lamina dissecans becomes partially filled, mostly with modified pyramidal cells of medium size that may constitute an incipient layer IV. A band of myelinated fibers corresponding to the external band of Baillarger is found within the lamina dissecans. The anterior insular sector is characterized by distinct lamination and a well‐defined, ribbonlike layer Va. In the middle sector, the cortex is internodense and lamination is less clear. The posterior sector is even less laminated and tends to be externodense. Within each sector, lamination becomes clearer in the direction of the circular sulcus. Furthermore, the rostrocaudal architectonic changes suggest a possible transition from a motor‐type to a sensory‐type cortex. Beyond the insula, the architecture of the opercular cortices reflect, in turn, the influences of the insular sectors.
Fractured cutaneous projections to the granule cell layer of the posterior cerebellar hemisphere of the domestic cat
Authors: Kassel Jeffrey , Shambes Georgia M. , Welker Wally
Published: January 2005

Snider's pioneering studies of tactile responses in the cerebellar cortex of cats and monkeys suggested that posterior regions of the cerebellar hemispheres receive somatotopically organized projections. However, recent studies in rats, using high‐density, in depth microelectrode mapping methods, have shown that tactile projections to the granule cell layer of the cerebellar hemispheres are somatotopically disrupted. We reexamined the Organization of cutaneous projections to eortibellar hemispheric cortex in cats by using micromapping methods.

Natural stimulation of cutaneous surfaces evokes short‐latency (mossy‐fiber‐induced) multiple unit responses in the cerebellar granule cell layer of crus II and paramedian lobule in both ketamine‐ and barbiturate‐anesthetized cats. Facial structures are represented in several of the most caudo‐medial folia of crus II as well as in three of the rostral folia of the paramedian lobule. In several of these paramedian folia, facial projections are interspersed with projections from the forelimb. Forelimb structures alone are represented in two intermediate folia of the paramedian lobule. No cutaneous projections were found from the trunk or hindlimb. All projections were from ipsilateral receptive fields.

In four folia of crus II and six folia of the paramedian lobule, cutaneous projections form a mosaic of patchlike projections. Within single patches, projections are somatotopically organized, but projections to adjacent patches come from noncontiguous body regions. Within a single folium, a particular facial region may be represented in two or three spatially separated patches. Facial patches are small, usually less than 1 mm2. Forelimb patches are usually larger, often extending the full length and breadth of a folial crown. Patches with like receptive fields are not organized in zonal sagittal strips. Rather than being somatotopically organized, cutaneous mossy fiber projections to granule cells in cats, as in rats, reveal a more complex mosaic pattern of organization.
The cytoarchitecture and some efferent projections of the centromedian‐parafascicular complex in the lesser bushbaby (Galago senegalensis)
Authors: Pearson J. C. , Norris J. R. , Phelps C. H.
Published: January 2005

The morphology of neurons in the centromedian (CM) and parafascicular (PF) nuclei in the lesser bushbaby (Galago senegalensis) is described in coronal and horizontal brain sections using Golgi‐, horseradish peroxidase (HRP)‐, and Nissl‐staining procedures. The CM contains two types of cells referred to as principal neurons and Golgi type II (like) neurons. Cell bodies of principal neurons are relatively large in cross‐sectional area (mean = 130.42 μm2), round to spindle in shape, support short somatic spines, and give rise to three to five primary dendrites. The dendrites branch in a “radiate” pattern and possess numerous appendages consisting of narrow, stalk‐supported swellings. The presumed axons of these cells are impregnated only in their initial segments. On the basis of the similarity of principal neuron soma shapes and cross‐sectional areas with those of HRP‐reactive somata following cortical HRP implantation, it is concluded that at least some of the principal neurons in Galago CM project to somatic sensory‐motor cortex. Golgi type II (like) neurons have small (mean = 79.43 μm2), round somata which support several spines and give rise to three to four small‐diameter dendrites. The dendrites are infrequently branched, sinuous in their courses, and give rise to complex appendages and beaded processes. However, the axons of these cells could not be seen to ramify in the immediate vicinity of the dendritic field or soma, and there is considerable overlap in the cross‐sectional areas of Golgi type II (like) neurons seen in Golgi preparations and HRP‐stained cells following cortical implant of HRP pellets. Consequently, although Golgi type II (like) cells have traits characteristic of classically described intrinsic neurons, a cortical projection of these cells cannot be ruled out by the present study.

The parafascicular nucleus contains two groups of large, radiate cells characterized by the presence or absence of somatic spines. Cells with somatic spines also contain numerous appendages on the dendrites. Cells without somatic spines support only a few, isolated, short dendritic appendages. Numerous small cell‐bodied neurons are present in Nissl‐stained sections of PF; however, cells which resemble Golgi type II neurons were not observed in the PF in the present Golgi‐impregnated material. In contrast to the CM, the large cell‐bodied neurons in PF were not found to project to somatic sensory‐motor cortex in Galago.
A sympathetic projection from sacral paravertebral ganglia to the pelvic nerve and to postganglionic nerves on the surface of the urinary bladder and large intestine of the cat
Authors: Kuo David C. , Hisamitsu Tadashi , De Groat William C.
Published: January 2005

Anatomical and electrophysiological experiments have demonstrated a prominent projection from the sacral sympathetic chain via the pelvic nerve to postganglionic nerves on the surface of the urinary bladder and the Large intestine of the cat. Retrograde labeling studies revealed that the pelvic nerve, which is generally believed to carry primarily parasympathetic axons, has a considerable population of sympathetic fibers originating mainly from the S1‐S3 paravertebral ganglia. The number of sympathetic neurons projecting to the pelvic nerve (2,100) was about.75% of that projecting to the pudendal nerve (2,900), a somatic nerve which would be expected to carry a large sympathetic fiber constituent. Sympathetic neurons projecting to the pudendal nerve were located primarily in the L6‐S2 ganglia. Electrophysiological studies confirmed the presence of a sympathetic pathway from the paravertebral ganglia to the pelvic viscera. Electrical stimulation (thresholds 1.5–3 V) of the lumbar sympathetic chain evoked firing in the pelvic nerve and in postganglionic nerves on the surface of the colon and bladder at latencies of 60–150 msec. The responses were unaffected by cutting the chain one segment rostral to the site of stimulation, but were abolished by the administration of a ganglionic‐blocking agent (tetraethylammonium). The responses on the colon and bladder postganglionic nerves were also abolished by transection of the pelvic nerve. The conduction velocity in the sympathetic postganglionic axons was approximately 1 m/second.

In summary, these studies indicate that the pelvic nerve, like somatic nerves, receives a prominent projection from the sympathetic chain ganglia. The function of this sympathetic paravertebral pathway and its relationship with prevertebral innervation of the pelvic organs remains to be established.
Abnormal central visual pathways in the brain of an albino green monkey (Cercopithecus aethiops)
Authors: Guillery R. W. , Hickey T. L. , Kaas J. H. , Felleman D. J. , Debruyn E. J. , Sparks David L.
Published: January 2005

The visual pathways of an albino green monkey have been studied electrophysiologically and by autoradiographic methods. The monkey had a white coat and pink eyes; it had a strabismus and a nystagmus. When comparisons were made with normal macaque and green monkeys, several abnormalities could be defined. In the retina there was no foveal pit. A whole mount preparation showed a central area of high ganglion cell density in which the ganglion cells were significantly larger than the most central ganglion cells of a normal monkey. More peripheral retinal areas showed an apparently normal distribution of ganglion cell sizes and packing densities. Within the optic tract the number of uncrossed retinofugal fibers was less than normal, the part of the tract that represents central vision showing almost no uncrossed component. The uncrossed input to the lateral geniculate nucleus and to the superior colliculus was similarly reduced. Regions normally receiving ipsilateral afferents from the central retina were innervated exclusively by crossed afferents. The pathways to the magnocellular geniculate layers showed a more extensive abnormality than did the pathways to the parvicellular layers. Not only were the afferents to the geniculate layers abnormal, but the laminar pattern in the nucleus was also abnormal. The distinction between magno‐ and parvicellular layers was less clear than normal in some parts of the nucleus, and there were a number of abnormal laminar fusions. Within the visual cortex it was possible to demonstrate a normal mapping of the contralateral visual field through the contralateral nasal retina and through the peripheral parts of the ipsilateral temporal retina. The central parts of the temporal retina mapped abnormally in the contralateral visual cortex, so that there was a monocular map of the central parts of the visual field forming as a mirror reversal of the normal map. The normal map of the contralateral hemifield formed columns that alternated with the abnormal map of the ipsilateral hemifield. The peripheral parts of the visual field were represented as ocular dominance columns, demonstrable electrophysiologically and also by the transneuronal transport of3H‐proline.
Light and electron microscopic studies of the distribution of microtubule‐associated protein 2 in rat brain: A difference between dendritic and axonal cytoskeletons
Authors: Bernhardt R. , Matus A.
Published: January 2005

A specific antiserum was used to ascertain the distribution of microtubule‐associated protein 2 (MAP2) in the rat brain at the light and electron microscope levels. Light microscopy showed MAP2 to be present only in neurons, and only in the dendrites and the perikaryon of each cell. This same polarized distribution pattern was found in the Purkinje, Golgi, basket, stellate, and granule cells of the cerebellum, and also in neurons of the hippocampus, the olfactory bulb, and the midbrain. While labelling of the dendritic arborization was extensive and intense, MAP2 density tended to decrease in the proximal dendritic trunk. Particularly in large neurons (e.g., Purkinje, Golgi, and pyramidal cells), staining was reproducibly weaker in the cell body than in the main dendrites. Dendritic contours generally appeared smooth, without any evidence of staining of dendritic spines. An electron microscope examination of the cerebellum confirmed the presence of MAP2 reactivity in neurons and its absence from axons and non‐neuronal cells. MAP2 in dendrites was associated with microtubules, while MAP2 in neuronal perikarya was associated with polyribosomes. There was no evidence of specific staining in dendritic spines and in postsynaptic densities. MAP2 is a novel dendritic marker and labels part of a specific dendritic cytoskeleton, different from that in axons and non‐neuronal cells.
Central neural connections of the pineal organ and retina in the teleost Gasterosteus aculeatus L.
Authors: Ekström Peter
Published: January 2005

The relations of the central neural connections of the pineal organ to those of the retinae of the lateral eyes were investigated in the three‐spined stickleback, Gasterosteus aculeatus L. (Teleostei), by anterograde and retrograde transport of horseradish peroxidase (HRP). HRP was applied to the crushed pineal stalk and/or injected into the left or the right eye. Both pineal and retinal efferents project to area praetectalis, dorsal and ventral thalamic areas, and dorsal tegmentum. The most notable overlapping occurs in nucleus commissurae posterioris of area praetectalis. Pineal efferents also innervate the habenular nuclei and dorsal hypothalamus, while retinal efferents innervate rostral hypothalamus, ventrolateral thalamus, and tectum opticum. A small number of retinofugal axons recross and innervate the ipsilateral nucleus anterioris periventricularis and area praetectalis. After intraocular HRP injections, labeled perikarya were located both in retinofugal terminal areas and in areas not receiving direct retinal input, such as the telencephalic nucleus olfactoretinalis, deep tectal layers, and an area rostroventral to nucleus dorsolateralis thalami. No neurons afferent to the pineal organ were demonstrated. The close association of pineal efferents with retinofugal and possible retinopetal elements is in accordance with the view that both systems are potential neural mediators of photoperiodic events in the teleostean circadian system.
Monoclonal antibody identifies a 63,000 dalton antigen found in all central neuronal cell bodies but in only a subset of axons in the leech
Authors: McKay Ronald , Johansen Jørgen , Hockfield Susan
Published: January 2005

The monoclonal antibody Lan3‐8 binds to all the neuronal cell bodies in midbody, head, tail, and supraesophageal ganglia in the mud leech (Haemopis marmorata) and the medicinal leech (Hirudo medicinalis). In contrast to the general distribution of the antigen in cell bodies it is only found in a subset of axons, where electron microscopy suggests that it may be associated with a cytoskeletal filament system. Immunoblotting shows that the antibody binds to a 63,000 dalton band that is protease‐sensitive. The same 63 kilodalton (kd) ‐antigen is found in all regions of the central nervous system, in proteins isolated from connectives (axons alone), and from handdissected identified cell types. The molecular weight and electron microscopic localization raised the possibility that this antigen is the core neuro‐filament protein, but the antigen does not comigrate with 67‐kd intense coomassie blue band that binds another anti‐intermediate filament antibody. The supraesophageal ganglia are known to have a different developmental origin from the other structures in the leech central nervous system. Two‐dimensional gel electrophoresis and silver staining show that, like the 63‐kd antigen, many other proteins are very similar in these developmentally distinct neural structures.
Axonal and dendritic development of substantia gelatinosa neurons in the lumbosacral spinal cord of the rat
Authors: Bicknell H. Ryan , Beal John A.
Published: January 2005

In the present study, developing neurons of the substantia gelatinosa (SG) are examined at short interval sequential stages from 15 days of gestation through 20 days postpartum. Rapid Golgi preparations are utilized to examine axonal and dendritic development and toluidine blue preparations are employed to study the overall growth pattern of SG cells by measuring changes in mean cell body area. Results show that there are two maturation periods, which involve two separate groups of SG neurons. The sequence and pattern of development for each group is different. The first period occurs prenatally and involves the axonal and dendritic development of presumptive projection and propriospinal neurons. In classical terminology, these cells can be classified as limiting, large find small central, and transverse cells. These neurons have axons that enter the white matter and their dendritic arbors develop through a relatively simple process of elongation and branching.

The second maturation period occurs postnatally and involves the development of presumptive nonprojection intrinsic neurons that have axons which remain within the gray matter. These neurons are identified as islet, stalk, inverted stalklike, and vertical cells. Unlike projection or propriopinal neurons, the intrinsic nonprojection neurons sprout numerous short, beaded dendrites that radiate from the cell body in a starlike fashion. Star‐shaped cells undergo a metamorphosis involving a rearrangement of dendrites along adult dendritic patterns.

Measurements taken from toluidine blue preparations indicate that the nonprojection intrinsic population makes up the greatest percentage of SG neurons, as evidenced by a marked increase in the size of the average SG nerve cell during the second maturation period.