bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal changes in vasopressin in the brain of the garden dormouse (Eliomys quercinus L.)
Authors: Hermes M. C. H. J. , Buijs R. M. , Masson‐Pévet M. , Pévet P.
Published: January 2005

The distribution of vasopressin in the brain of the garden dormouse (Eliomys quercinus L.) was examined by immunocytochemistry at different times of the year. In spring‐summer, sexual dimorphism in the density of vasopressin labeling was observed in several areas of the brain. In these regions, such as the lateral septum and the nucleus of the vertical limb of the diagonal band of Broca, male garden dormice showed more vasopressin immunoreactivity than their female counterparts. In autumn‐winter, at the time of hibernation, vasopressin was undetectable in the sexually dimorphically innervated brain regions in males as well as females. In early spring, there was large variation in vasopressin staining in the male brain, whereas the female brain was consistently lacking in vasopressin labeling. In brain regions that exhibited no sexually dimorphic innervation in the summer, vasopressin labeling remained the same throughout the year. The difference in the amount of vasopressin immunoreactivity in males in summer and winter correlated significantly with differences in testes weight. In early spring, because of interindividual variations in the start of sexual activation, testes size does not correlate with the density of vasopressin immunoreactivity.

Similar seasonal variations in density of vasopressin labeling in the brain were also observed in the European hamster (Cricetus cricetus). In this animal, central vasopressin infusion during the winter prevents hibernation. The presence of a similar pattern of changing vasopressin content in another hibernator, the garden dormouse, suggests an important role for this neuropeptide in seasonal functions.

In the garden dormouse, vasopressin fibres could be detected in a number of brain regions where, in other rodents, such fibres are undetectable, e.g., the interpeduncular complex and the lateral superior olive. It is suggested that the central vasopressin system in the rat and European hamster is essentially the same as in the garden dormouse, but more difficult to detect immunocytochemically.
Early development of retinal ganglion cell dendrites in the marsupial Setonix brachyurus, Quokka
Authors: Dunlop S. A.
Published: January 2005

The dendritic morphology of retinal ganglion cells was studied in flatmounted retinae of the marsupial Setonix brachyurus, quokka. In the adults, horseradish peroxidase (HRP) was applied to the vitread surface of flattened retinae. Wide‐, large‐, medium‐, and small‐field classes appeared to correspond to gamma, alpha, delta, and beta cells, respectively, in the cat (Boycott and Wässle, J. Physiol.249:397‐419, 1974).

To reveal the early stages of dendritic development, HRP was placed on the optic nerve of isolated eye cups from the day of birth to postnatal day (P) 63 when the area centralis is beginning to form (Dunlop and Beazley, Dev. Brain Res.23:81‐90, 1985). Youngest cells lacked dendrites and had an elongate soma in the cytoblastic layer with an endfoot contacting the ventricular surface. Once in the ganglion cell layer, the soma was rounded and dendrites appeared as short, unbranched processes. Most cells were asymmetric or „polarised”︁ with the axon arising from the side nearest the optic disk and dendrites from the opposite side. Polarity was maintained in cells with longer, branched dendrites. A small proportion of cells exhibited a reversed polarity in which the axon arose from the side nearest the retinal edge and dendrites towards the disk. Cells appeared to acquire an approximately symmetric, adult‐like tree by the addition of new primary dendrites between the existing ones and the axon hillock. Wide‐, large‐, medium‐, and small‐field cells were evident from P6, P25, P31, and P40, respectively. Spines were observed on dendrites and axons during development but were rare in the adult. Some den‐dro‐axons were seen at all ages examined.

The existence of an initial axodendritic polarity in retinal ganglion cells supports the hypothesis that the axon hillock is the determinant of dendritic geometry (Maffei and Perry, Dev. Brain Res. 41:185‐194, 1988). Polarity may also contribute to the establishment of „radial orientation”︁ in which the long axis of the elliptical dendritic tree of cells outside the area centralis points towards central retina and the weighted centre is displace towards the retinal periphery (Leventhal and Schall, J. Comp. Neurol. 220:465‐475, 1983).
Electron microscopic study of immunocytochemically labeled centrifugal fibers in the goldfish retina
Authors: Kawamata Kunihiko , Ohtsuka Teruya , Stell William K.
Published: January 2005

The centrifugal fibers innervating the goldfish retina were studied quantitatively by light and electron microscopy. These fibers originating from cell bodies in the olfactory bulb were labeled by antiserum to the tetrapeptide Phe‐Met‐Arg‐Phe‐NH2 (FMRFamide). The number of FMRFamide‐immunoreactive (ir) centrifugal fibers in each eye of the adult goldfish (body length: 12‐15 cm) was 65 + 14 (mean ± S. D., n = 7). All of these fibers in the optic nerve and the retina were unmyelinated. Each FMRFamide‐ir centrifugal fiber runs along the optic fiber layer and gives several terminal arborizations in the outermost layer (layer 1) of the inner plexiform layer. Layer 1 is, therefore, densely covered by a plexus of terminal arborizations. Along these terminal arborizations, we found output synapses characterized by a cluster of small clear vesicles (40 nm in diameter) at the presynaptic site and a thickened membrane in the apposed retinal cell processes. In a sample area of 2,000 üm2, such synapses occurred at a density of one per 105 üm2, or about 13,000 per centrifugal fiber. Thus, the FMRFamide‐ir centrifugal fibers are likely to modulate retinal cell activity through an estimated total of 840,000 output synapses per retina.
Quantitative fine structure of capillaries in subregions of the rat subfornical organ
Authors: Shaver Steven W. , Sposito Nadine M. , Gross Paul M.
Published: January 2005

The differentiated cytology across subregions of the rat subfornical organ (SFO) prompted our hypothesis that ultrastructural features of capillary endothelial cells would vary topographically and quantitatively within this small nucleus. We used electron microscopic and computer‐based morphometric methods to assess fine structural dimensions of the capillary endothelium in four distinct subregions of the SFO from Long‐Evans and homozygous Brattleboro rats. Three types of capillary were present. Type III capillaries (resembling those of endocrine glands) had an average wall thickness of 0.17 μm, 54% thinner than those of Type I and II capillaries. Pericapillary spaces around Type III capillaries measured 56 μm2, 100% larger than for Type I vessels (resembling those of skeletal muscle). Only Type III capillaries contained fenestrations (9 per μm2 of endothelial cell) and were the predominant type of capillary in central and caudal subregions of the SFO. Type I capillaries, prevalent in the transitional subregion between the central and rostral parts of the SFO, had 10 cytoplasmic vesicles per μm2 of endothelial cell area, a number not different from that of Type III capillaries but 3× the frequency found in Type II vessels. Type II capillaries (those typical of “blood‐brain barrier”endothelium) had low vesicular density (3 per μm2), no fenestrations, and no pericapillary spaces. Luminal diameters and the densities of mitochondria and intercellular junctions were not different among capillary types or subregions in the SFO. Furthermore, there were no morphometric differences for any capillary dimensions between Long‐Evans and Brattleboro rats. These studies reveal quantitative differences among capillary networks in four distinct compartments of the rat SFO and provide morphometric dimensions for the three types of capillary existing in this cerebral sensory nucleus.
Organization of retinopetal axons in the optic nerve of the cichlid fish, Herotilapia multispinosa
Authors: Rusoff Anne C. , Hapner Sharon J.
Published: January 2005

We have studied the position and numbers of retinopetal axons in the rainbow cichlid fish, Herotilapia multispinosa, to determine the response of related parts of the brain of fish to the continual addition of new neurons in the retina. The retinopetal axons were traced by using the retrograde tracers HRP and cobaltous lysine and an immunocytochemical probe, antibodies to FMRFamide, the molluscan cardioexcitatory peptide. One population of cells with retinopetal axons was found in the telencephalon (in the nucleus olfactoretinalis) and the other was scattered in the diencephalon. Some of the cells in the nucleus olfactoretinalis with retinopetal axons were FMRFamide positive; antibodies were used to trace the axons of these cells into the retina. All the retinopetal axons, from the nucleus olfactoretinalis and the diencephalon, were confined to the portion of the optic nerve that contains axons from the central retinal ganglion cells, that is, the oldest ganglion cells. Theis result suggests that the retinopetal axons grow into the optic nerve and retina early in the life of the fish, and no new ones are added later in life despite the extensive addition of cells in the retina. Counts of the cells in the nucleus olfactoretinalis that project to the retina in 3‐month‐old and adult fish support this interpretation. We conclude that retinopetal axons grow into the retina early in the life of the fish and respond to the formation of new retina by extending their arbors toward the new retina.
Development of retinopetal projections in the cichlid fish, Herotilapia multispinosa
Authors: Rusoff Anne C. , Hapner Sharon J.
Published: January 2005

This paper reports a study of the development of cells that project to the retina from the telencephalic nucleus olfactoretinalis and the diencephalon. Stell et al. (Proc. Natl. Acad. Sci. USA 81:940‐944,'84) have shown that the FMRFamide‐immunoreactive (FMRFamide‐ir) cells in the nucleus olfactoretinalis project to the retina. Therefore, we used immunocytochemistry to study the development of these cells in the nucleus olfactoretinalis. Twenty hours after fry hatched, FMRFamide‐ir cells were unambiguously seen in the nucleus olfactoretinalis. At this time the axons of these cells could be traced into the optic nerve. A few hours later the axons were visible in the retina and soon attained their adult position in the inner plexiform layer near the amacrine cells.

In older fry, tracers were used to fill retinopetal cells in both the nucleus olfactoretinalis and the diencephalon. Counts of these cells demonstrated that over one‐third of the adult number of retinopetal cells in the nucleus olfactoretinalis are present and have axons in the retina when the fry is 9 days old, and the percentage grows to one‐half by the time the fry is 1 month old. Development of the retinopetal cells in the diencephalon lags behind that of the cells in the nucleus olfactoretinalis. However, about one‐third of the adult number extend their axons into the optic nerve by 1 month of age.

These results support our suggestion that the retinopetal cells have axons in the old part of the optic nerve because these cells were born and extended axons early in the life of the fish.
Synapses formed by olivocochlear axon branches in the mouse cochlear nucleus
Authors: Benson T. E. , Brown M. C.
Published: January 2005

Cochlear nucleus branches of thick olivocochlear axons were labeled by injections of horseradish peroxidase into the spiral ganglion of the cochlear basal turn in mice. Six labeled axons were traced by light microscopy, and selected portions of seven branches were sectioned serially for electron microscopic examination. Axonal branches most frequently terminated near certain granule cell regions of the ventral cochlear nucleus. This article describes terminals, synapses, and postsynaptic elements of these olivocochlear branches.

The olivocochlear branches had both terminal and en passant boutons that contained round vesicles and made asymmetric synapses with other neuronal processes. About a quarter of the synapses also possessed additional specializations, postsynaptic, or subjunctional bodies. Mossy terminals, a multisynaptic type of terminal commonly found in granule cell regions, were not found arising from any of the labeled branches. No somatic synapses were found, although contacts with cell bodies were occasionally observed.

The predominant synaptic target of olivocochlear branches were what appeared to be dendrites of large diameter. At least some of these large dendrites received multiple synapses from a single labeled olivocochlear branch. The morphological characteristics of reconstructed dendrites suggest that multipolar cells might be predominant targets for the medial olivocochlear system in the cochlear nucleus. This was demonstrated in one case in which a large dendrite was followed to its cell body of origin.
Distribution of quinolinic acid phosphoribosyltransferase in the human hippocampal formation and parahippocampal gyrus
Authors: Du Fu , Okuno Etsuo , Whetsell William O. , Köhler Christer , Schwarcz Robert
Published: January 2005

The morphological distribution of quinolinic acid phosphoribosyltransferase (QPRT), the degradative enzyme of the endogenous excitotoxin quinolinic acid, was studied in the human hippocampal formation and parahippocampal gyrus by immunohistochemical techniques. In seven neurologically normal human brains obtained at autopsy, QPRT ‐ immunoreactivity (QPRT‐i) was found in both glial cells and neurons. Glial cells exhibiting QPRT‐i, sharing the morphological features of astrocytes, were observed in all hippocampal subfields. The polymorphic layer of the dentate gyrus contained the highest density of QPRT‐i glial cells. Numerous QPRT‐i glial cells were also found along both sides of the fused hippocampal fissure and in the white matter including the alveus of Ammon's horn, whereas only a few were observed in the granule cell layer and the stratum pyramidale. Neurons containing QPRT‐i were found mainly in the subiculum and in the strata oriens and pyramidale of CA1. They were mostly small and polymorphic or fusiform, thus indicating that they may belong to a subpopulation of interneurons. Moderate numbers of QPRT‐i glial cells and neurons were also observed throughout layers II‐VI of parahippocampal cortex. The localization of QPRT‐i in selected glial cells and neurons suggests that in the regions examined these cellular elements might play specific roles in the regulation of quinolinic acid function.
Target dependence of chick retinal ganglion cells during embryogenesis: Cell survival and dendritic development
Authors: Vanselow Jens , Dütting Dieter , Thanos Solon
Published: January 2005

The survival of retinal ganglion cells and the dendritic development were investigated (a) in normal chick embryos, (b) in embryos whose primordial optic lobes and adjacent areas were removed (target reduced embryos), and (c) in embryos whose optic nerves were transected (target deprived embryos) in order to study the influences of central targets on developing ganglion cells. The ganglion cells were stained postmortem with the carbocyanine dye DiI. Cell body and dendritic field diameters were measured in whole‐mounted retinae before and after the period of cell death at embryonic day 10 (E10) and E16. The cell densities within the ganglion cell layer were counted in cresyl violet/thionine stained retinae. The central retinal projection in target reduced embryos was studied with the anterogradely transported fluorescent marker rhodamine‐B‐isothiocyanate (RITC).

In normal embryos, the earliest dendritic processes were observed at E6 in the central retina, whereas at E10 elabrate dendritic branching was found across the retina. Different morphological types of ganglion cells could be identified at E16. In both, target reduced embryos and target deprived embryos, the initial dendritic growth and pattern of ramification were indistinguishable from those of normal embryos up to E10. Cell body diameters, dendritic tree diameters, and cell densities were not significantly different. At the end of the naturally occurring cell death period (E16), the ganglion cell density was strongly reduced in both experimental groups compared to controls. In particular, when the optic nerve was transected, it resulted in the almost complete degeneration of ganglion cells. In target reduced embryos, a small population (about 5% of the normal number) of ganglion cells survived. The proportion of large cells was increased within the total population compared to normal retinae. Displaced ganglion cells were not affected by partial target removal but strongly affected by transection of the optic nerve. Anterograde labelling from the retina revealed that in target reduced embryos the remaining ganglion cells innervated non‐tectal primary visual nuclei.

The present results suggest the following: (a) Before the onset of the cell death period, the growth and ramification of ganglion cell dendrites occur independently of central visual targets. (b) In target reduced embryos, a small population of ganglion cells survives, namely, those cells that project to remaining central areas. Complete disconnection from central targets by transecting the optic never leads to the degeneration of almost all ganglion cells. (c) The surviving ganglion cell population consists mainly of large ganglion cells.
Spatial organization of axons in turtle visual cortex: Intralamellar and interlamellar projections
Authors: Cosans Christopher E. , Ulinski Philip S.
Published: January 2005

The spatial pattern of projections within turtle visual cortex was studied by using focal injections of horseradish peroxidase into visual cortex in an in vitro wholebrain preparation. Injections anterogradely filled the axons of many layer 2 neurons, which could be followed for 200–500 μm from the injection sites. Axons were typically unbranched, relatively straight, and bore small varicosities at irregular intervals. They radiated from the injection sites in all directions, but showed some preference toward orientations along the lateral‐medial axis of the cortex. Earlier work ((Mulligan and Ulinski,'90)) had demonstrated that turtle visual cortex contains a series of isoazimuth lamellae, each representing an individual azimuth of visual space and oriented perpendicular to the rostral‐caudal axis of the cortex. The present study provides evidence for intrinsic projections both along isoazimuth lamellae and between adjacent lamellae. These projections may play roles in the elaboration of wide receptive fields of cortical neurons.
Endogenous peroxidatic activity in astrocytes after spinal cord injury
Authors: Noble L. J. , Cortez Selina C. , Ellison J. A.
Published: January 2005

After spinal cord injury, endogenous peroxidatic‐like activity develops along the axis of the cord. At 2 weeks postinjury, this activity appears in cells whose processes are intimately associated with microvessels. The objectives of this study were to further characterize this response and to identify the cellular localization of endogenous peroxidatic‐like activity.

After traumatic injury to the rat spinal cord, adjacent sections of spinal cord were processed in medium to visualize antiglial fibrillary acidic protein, endogenous peroxidatic activity, or cytochrome oxidase activity. In addition, certain sections, stained for endogenous peroxidatic‐like activity, were prepared for electron microscopy. To identify the nature of the activity, some sections were exposed to an incubation medium that included inhibitors of either catalase or heme protein activity.

The distribution of prominent glial fibrillary acidic protein immunoreactivity in the dorsal columns corresponded to that of marked staining for endogenous peroxidatic‐like activity and cytochrome oxidase. At the ultrastructural level, endogenous peroxidatic‐like activity was identified in the cytoplasmic compartment of the astrocyte. This activity was abolished when potassium cyanide (an inhibitor of heme protein) was added to the incubation medium.

Spinal cord injury elicited a pronounced cellular response along the axis of the cord that was characterized by enhanced staining for antiglial fibrillary acidic protein, cytochrome oxidase activity, and endogenous peroxidatic‐like activity. It is not clear whether pronounced cytochrome oxidase activity corresponded to astrocytes that also expressed prominent endogenous peroxidatic‐like activity. However, according to both light and ultrastructural findings, endogenous peroxidatic‐like activity was prominently associated with the astrocytic cytoplasm. The biochemical nature of the peroxidatic activity is unknown, but these results suggest that it is related to a heme‐containing protein.
Morphology of the human olfactory epithelium
Authors: Morrison Edward E. , Costanzo Richard M.
Published: January 2005

The human olfactory epithelium has been previously studied with scanning electron microscopy; however, most studies have been limited to examining the epithelial surface. In an attempt to examine structures below the surface, we scanned epithelial fractures that occurred during tissue preparation. This made it possible to obtain unique three‐dimensional images of cell profiles from the mucosal surface through the full depth of the epithelium. We examined supporting cells, olfactory neurons, basal cells, and a fourth cell type, the microvillar cell. Supporting cells had a microvillar surface and were in close contact with olfactory neurons and their processes. Olfactory neurons were primarily located in the middle and lower epithelial regions. Basal cells occurred alone or in clusters adjacent to the basal lamina. Microvillar cells were always observed in the upper epithelial region. They were flask‐ or pear‐shaped, had a tuft of microvilli that extended into the nasal cavity, and a thin axon‐like process that passed basally towards the lamina propria.

This study represents the first comprehensive scanning electron microscopy examination of the human olfactory epithelium. Three‐dimensional images obtained for each epithelial cell type allowed us to examine cell processes and their close contacts, especially between supporting cells and olfactory neurons. These results also revealed the irregular and patchy distribution of olfactory receptors within the human nasal cavity. Further studies that examine the detailed morphology of the human olfactory epithelium should provide a better understanding of the physiological mechanism and clinical disorders that affect olfactory function in humans.
Intracellular recording and injection study of corticospinal neurons in the rat somatosensory cortex: Effect of prenatal exposure to ethanol
Authors: Miller Michael W. , Chiaia Nicholas L. , Rhoades Robert W.
Published: January 2005

The effects of prenatal exposure to ethanol on the structure and function of corticospinal neurons was investigated. The subjects were the 3–4‐month‐old offspring of hooded rats fed a nutritionally balanced liquid diet containing 6.7% (v/v) ethanol (Et), pair‐fed a nutritionally matched isocaloric diet (Ct), or fed chow and water (Ch). Corticospinal neurons in primary somatosensory cortex were examined by intracellularly recording and filling cells that were driven by antidromic stimulation of the pyramidal decussation.

In the control rats, corticospinal neurons comprised a homogeneous morphophysiological population. Morphologically, all of the antidromically driven cells examined were pyramidal neurons with cell bodies in layer Vb. The dendrites of these neurons were spinous and branched within layers I, IV, and V. Their axons arborized within layers IV, V, and VI and some collaterals extended laterally for distances up to 2.6 mm from the cell body. The mean conduction latency was 3.6 and 3.4 msec for Ch‐ and Ct‐treated rats, respectively.

In Et‐treated rats, corticospinal neurons constituted a heterogeneous population. The laminar distribution of the corticospinal neurons in Et‐treated rats was broad; the cell bodies of labeled neurons were in layers II, IV, V, and VI. The dendrites of layer Vb neurons were spinous; however, many of the spines appeared dysmorphic and the density of spines was significantly greater (32%) in Et‐treated rats than in Ct‐treated rats. Although the dendritic branching pattern for layer Vb neurons was similar to that described for the controls, a Sholl analysis showed that the complexity and extent of their dendritic trees were significantly greater in Et‐treated rats. The axons of all layer Vb neurons in Et‐treated rats had long horizontal processes that arborized in layers IV–VI, and some neurons also had an array of collaterals that ascended to layer I. The mean conduction latency for layer Vb neurons was 3.9 msec. The structure and function of ectopic neurons (those in layers II, IV, Va, Vc, and VI) in Et‐treated rats differed markedly from those of the layer Vb neurons. Morphologically, the dendritic and axonal fields of these neurons were narrower than for the layer Vb neurons, and the ectopic neurons had a mean conduction latency of 7.1 msec.

The heterogeneity of the population of corticospinal neurons in Et‐treated rats may result from the effects of ethanol on early events in neuronal development such as neuronal generation and migration.
Early axon and dendritic outgrowth of spinal accessory motor neurons studied with dii in fixed tissues
Authors: Snider William D. , Palavali Vivekanand
Published: January 2005

We have utilized lateral diffusion of DiI in fixed tissues (Godement et al., '87: Development 101: 697–713) to study early axon and dendritic outgrowth of spinal accessory motor neurons in embryonic rats. Crystals were placed in the central canal of the cervical spinal cord near the ventral commissure in order to label growing accessory axons anterogradely and on the spinal accessory nerve to label somata and dendrites retrogradely. Animals were studied on E11–E13.

We show here that it is possible to stain axonal and dendritic processes from the earliest stages of motor neuron differentiation by using DiI. Our results demonstrate that, unlike axons of other cervical motor neurons, accessory axons traverse the lateral region of the embryonic cord, which consists of neuroepithelial endfeet. Thus an affinity for neuroepithelial endfeet could partially explain their unusual intraspinal trajectory. We also show that morphology of the spinal accessory growth cones differs according to position along the accessory nerve pathway. Finally, we show that accessory motor neuron axons are in the region of their target precursors prior to the initiation of dendritic arborization. Use of DiI in fixed tissue allows study of process outgrowth in mammalian spinal cord with detail previously obtainable only in nonmammalian vertebrates.
Termination patterns of serotoninergic medullary raphespinal fibers in the rat lumbar spinal cord: An anterograde immunohistochemical study
Authors: Jones S. L. , Light A. R.
Published: January 2005

Electrical and chemical stimulation given in the ventral medullary raphe nuclei inhibits spinal nociceptive reflexes and spinal nociceptive transmission; serotoninergic receptors have been demonstrated to partially mediate that inhibition. In the present study, the termination patterns of raphespinal fibers in the rat lumbar spinal cord demonstrating serotonin‐like immunoreactivity were examined by using the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA‐L) in combination with immunohistochemistry.

Fibers and terminations from the ventral medullary raphe nuclei (raphe magnus and raphe pallidus) demonstrating both PHA‐L‐ and serotonin‐like immunoreactivity were identified in all laminae of the dorsal horn and the ventral horn. Networks of large fibers, characterized by large boutons, and which did not demonstrate serotonin‐like immunoreactivity, were identified in deeper laminae of the dorsal horn. The heterogeneous morphology of raphespinal fibers identified in the dorsal horn suggests that these fibers also may be heterogeneous in neurochemistry and function.

Medial medullary sites outside the raphe nuclei were found to innervate the ventral horn and all laminae of the dorsal horn, with the exception of lamina I. Descending fibers and terminations also demonstrating serotonin‐like immunoreactivity were identified in deep laminae (III, IV, V, VI) of the dorsal horn and in the ventral horn. Similarly, large fiber networks were identified which did not demonstrate serotonin‐like immunoreactivity.
Microtubule‐associated protein 2 (MAP2) in Purkinje cell dendrites: Evidence that factors other than binding to microtubules are involved in determining its cytoplasmic distribution
Authors: Matus Andrew , Delhaye‐Bouchaud Nicole , Mariani Jean
Published: January 2005

We have studied the distribution of microtubule‐associated protein 2 (MAP2) in the Purkinje cell dendrites of rats whose cerebella were exposed to X‐irradiation during the second postnatal week. The Purkinje cells of such animals have abnormally elongated apical primary processes that branch in the outer molecular layer rather than close to the cell body as in normal tissue. The results show that in these distorted dendrites the MAP2 distribution is “shifted” distally relative to the normal pattern, in which MAP2 is distributed evenly throughout the dendritic tree. Tubulin and other microtubule‐associated proteins, such as MAP1, are not affected and remain evenly distributed throughout the dendritic tree despite the anatomical distortion. We conclude that the distribution of MAP2 in Purkinje cells is not determined solely by its binding to tubulin. Other factors must be involved and these appear to be related to dendritic morphology and possibly to branching.
Corticocortical connections predict patches of stimulus‐evoked metabolic activity in monkey somatosensory cortex
Authors: Juliano Sharon L. , Friedman David P. , Eslin Don E.
Published: January 2005

Stimulus‐evoked metabolic activity in the anterior parietal cortex (areas 3a, 3b, 1, and 2) occurs in the form of column‐like patches. Similar patches characterize the connections to, within, and from these fields. The relation of the patches elicited metabolically to those formed by retrograde or anterograde transport, however, is not clear. If a type of projection connecting areas 3a, 3b, 1, and 2 transmits sensory information among these cortical fields, the resultant projection pattern may directly contribute to the definition of somatosensory metabolic “columns.” To test this possibility, electrophysiological recordings in areas 3b and 1 of Macaca fascicularis monkeys characterized stimuli that elicited the best neuronal response at a specific cortical site. Iontophoretic injections of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) were subsequently made into the identified cortical sites. Two days later, the animals were injected with 2‐deoxyglucose (2DG) and received the somatic stimulus previously determined to best activate the neurons isolated at the injected cortical site. After injections of WGA‐HRP into physiologically defined loci in area 3b, the patches of transported label within areas 3b and 1 were colocalized with evoked metabolic activity. Injections of WGA‐HRP into area 1 produced anterogradely labeled terminals in areas 1 and 2 that also overlapped with patches of evoked metabolic activity, as did patches of retrogradely labeled cells located in area 3b. Patches of anterograde label found in area 3b after area 1 injections, however, were not coincident with the metabolically activated patches. These findings suggest that excitatory information is transmitted from area 3b to area 1 in a way that connects clusters of cells with similar response properties.
Vasopressinergic innervation of the mouse suprachiasmatic nucleus: An immuno‐electron microscopic analysis
Authors: Castel M. , Feinstein N. , Cohen S. , Harari N.
Published: January 2005

Attempts are being made to unravel the local circuitry of the suprachiasmatic nucleus, with a view toward eventually correlating specific neuronal systems with circadian events. Hence, the vasopressinergic innervation of this nucleus in the laboratory mouse has been analyzed immunocytochemically at the light and electron microscopical levels. Monoclonal antineurophysin and polyclonal antivasopressin were used on aldehyde‐fixed brains. Serial vibratome sections of the appropriate forebrain region were prepared for pre‐embedding immunoperoxidase staining and/or postembedding immunogold labeling.

Immunoreactive somata, processes, varicosities, and synaptic terminals were found throughout the suprachiasmatic nucleus, their ratio and density varying at different locations. The predominant type of vasopressinergic soma was ovoid to rounded (7–10 μm) containing secretory granules (85–120 nm), a large proportion of which were immunoreactive.

Axon terminals, both nonimmunoreactive and immunoreactive, impinged upon vasopressinergic somata and processes, often displaying synaptic specializations. Vasopressinergic terminals, containing secretory granules and microvesicles, were found throughout the nucleus, particularly within the dorsomedial neuropil. These labeled terminals varied in size (0.4–3.4 μm2) and shape, ranging from compact boutons to pleomorphic profiles, some deeply indented by postsynaptic spines, either dendritic or somatic. Approximately 65% of the vasopressin‐containing terminals were axodendritic and 30% axosomatic; about 5% appeared to be axoaxonic. At least a quarter of all vasopressinergic synaptic terminals were axospinous.

Other forms of interneuronal contact involving vasopressinergic elements (somata, dendrites) included extensive membrane to membrane appositional sites, and multiple puncta adhaerentia.

The versatility of interconnections between vasopressin‐containing neurons in the mouse suprachiasmatic nucleus suggests a highly active and coordinated network, which contributes substantially to local intranuclear circuitry. In addition, a dense efferent vasopressinergic output is directed dorsally towards the periventricular hypothalamus, where direct associations may he established with diverse hypothalamic neuroendocrine systems.
Distribution of septohippocampal neurons containing parvalbumin or choline acetyltransferase in the rat brain
Authors: Kiss Jozsef , Patel Ambrish J. , Freund Tamas F.
Published: January 2005

A combination of retrograde transport of horseradish peroxidase or wheat germ agglutinin‐colloidal gold with either single or double‐label immunohistochemistry is used to describe the comparative topographic distribution of parvalbumin‐ and choline acetyltransferase‐immunoreactive septal neurons that project to the hippocampal formation of the rat. The morphometric parameters of the retrogradely labelled, parvalbumin‐containing neurons were very similar, if not identical, to those neurons of the midline and medial part of the medial septum and the diagonal band regions that had previously been shown to be immunoreactive for γ‐aminobutyric acid or for glutamate decarboxylase following colchicine treatment. The total number of parvalbumin‐immunoreactive and choline acetyltransferase‐positive retrogradely labelled cells was counted at 9 representative levels through the rostrocaudal extension (from 2.4 mm anterior to the level of bregma) of the medial septal‐diagonal band complex. In the whole medial septum‐vertical limb of the diagonal band region, about 33% of the total retrogradely labelled neurons showed immunoreactivity to parvalbumin, whereas the parvalbumin‐negative cells were mainly choline acetyltransferase‐immunopositive. In comparison with the average figure, the proportion of the retrogradely labelled parvalbumin‐containing neurons was higher in the middle part (around 1.5 mm anterior to the bregma) than in either the rostral or caudal ends. The reverse was true for the distribution of the cholinergic septohippocampal neurons. At the maximum levels the parvalbumin‐immunoreactive neurons accounted for more than half of the total retrogradely labelled cells in 4 out of 6 rats. Moreover, within the complexity of the septal neurons, a marked regularity of topographic organisation was observed in the distribution of retrogradely labelled parvalbumin‐containing GABAergic and choline acetyltransferase‐positive cholinergic neurons as if they were subdivided cytoarchitectonically.
Distribution and brainstem origin of cholecystokinin‐like immunoreactivity in the opossum cerebellum
Authors: King James S. , Bishop Georgia A.
Published: January 2005

In order to determine the distribution of the peptide cholecystokinin (CCK) within the cerebellum and medullary precerebellar nuclei of the adult opossum, sections of these brain regions were processed for peroxidase‐antiperoxidase immunohistochemistry. Within the inferior and superior cerebellar peduncles, fine‐beaded fibers are evident and a beaded plexus of fibers is present in all the cerebellar nuclei. In the overlying cerebellar cortex, CCK‐positive mossy fiber rosettes are present in all lobules, where their morphology varies from simple enlargements to more complex rosettes. However, their distribution varies particularly in vermal lobules II, III, VII, and IX where they are organized in parasagittal bands. Climbing fibers that are positive for CCK are present in very restricted areas of vermal lobules IV, VII, and VIII. After colchicine pretreatment, CCK‐positive cell bodies are seen in restricted regions of the posterior interposed and fastigial nuclei as well as within several precerebellar nuclei known to give rise to mossy fibers. Such nuclei include the lateral cuneate nucleus, the nucleus prepositis hypoglossi, the nucleus reticularis latefalis, the nucleus raphe obscurus, the paramedian reticular nucleus, the nucleus reticularis gigantocellularis, and the medial vestibular nucleus. To localize the brainstem origin(s) of the CCK fibers in the cerebellum, a double‐label paradigm employing a retrograde tracer and CCK immunohistochemistry was used. These experiments indicate that CCK mossy fibers originate primarily within the lateral cuneate nucleus, the perihypoglossal complex, and the lateral reticular nucleus. Some also originate within the medial vestibular nucleus and the nucleus reticularis gigantocellularis. In addition, double‐labeled cell bodies are present within the caudal medial accessory inferior olive, the likely source of the CCK‐positive climbing fibers. These data indicate that specific populations of climbing fibers and mossy fibers may utilize CCK to alter the firing rate of their target neurons.
Prenatal development of retinogeniculate projections in the rabbit: An HRP study
Authors: Crabtree John W.
Published: January 2005

The prenatal development of the rabbit's retinal projections to the dorsal lateral geniculate nucleus (dLGN) was studied by using anterograde axonal transport of HRP injected intraocularly. Further, the ontogenesis of the dLGN's α and β sectors was studied. Fetuses aged embryonic day 18 (E18) to E29 were examined. Gestation in the rabbit is 30–31 days.

On E18 the future dorsal lateral and medial geniculate nuclei appear as a continuous strip of cells along the lateral margin of the dorsal thalamus. On E21 labelled retinal fibers are invading the lateral margin of the dLGN contralateral, but not ipsilateral, to an injected eye. At this age the dorsal lateral and medial geniculate nuclei are separating. By E23 contralateral fibers occupy the entire presumptive α sector, while ipsilateral fibers are invading the caudal half of the sector, overlapping the contralateral fibers. At this age the α and β sectors begin to differentiate. On E25 contralateral fibers are more densely distributed throughout the α sector and the ipsilateral fibers are concentrated dorsally within the caudal three‐quarters of the sector. By E27 contralateral fibers begin to withdraw from a medial zone of the α sector, while ipsilateral fibers remain densest in this zone and begin to withdraw from more lateral and caudal aspects of the sector; contralateral fibers, but not ipsilateral fibers, invade the β sector. At this age the α and β sectors acquire an adult‐like appearance. By E29 the contralateral fibers vacate the β sector and the medial zone of the dLGN and the ipsilateral fibers are restricted to this zone. Thus, 1 or 2 days before birth, the locations of the ipsilateral and contralateral retinal projections to the dLGN resemble those seen in the adult.

The early overlapping projections of ipsilateral and contralateral retinal fibers within the dLGN and their eventual segregation in the fetal rabbit are consistent with the development of these projections in other mammalian orders. Further, the brief invasion of the β sector by the contralateral fibers resembles the transient occupation of the carnivores' perigeniculate nucleus by developing retinal fibers. In addition, direct comparisons of temporal and spatial events during retinal innervation of the dLGN and the superior colliculus indicate several developmental differences between the two nuclei.
Neuronal connections between the cerebellar nuclei and hypothalamus in Macaca fascicularis: Cerebello‐visceral circuits
Authors: Haines D. E. , May P. J. , Dietrichs E.
Published: January 2005

The purpose of this study was to identify the basic pattern of interconnections between the cerebellar nuclei and hypothalamus in Macaca fascicularis. The distribution of retrogradely labeled cells and anterogradely filled cerebellofugal axons in the hypothalamus of M. fascicularis was investigated after pressure injections of a horseradish peroxidase mixture (HRP + WGA‐HRP) in the cerebellar nuclei. Following injections in the lateral, anterior, and posterior interposed cerebellar nuclei retrogradely labeled cells were present in the following areas (greatest to least concentration): lateral and dorsal hypothalamic areas, dorsomedial nucleus, griseum periventriculare hypothalami, supramammillary and tuberomammillary nuclei, posterior hypothalamic area, ventromedial nucleus and periventricular hypothalamus, around the medial mammillary nucleus, lateral mammillary nucleus, and infundibular nucleus. Cell labeling was bilateral with an ipsilateral preponderance. In these same experiments anterogradely labeled cerebellar efferent fibers terminated in the contralateral posterior, dorsal and lateral hypothalamic areas, and the dorsomedial nucleus. In these regions retrogradely labeled hypothalamic cells were occasionally found in areas that also contained anterogradely filled cerebellar axons. This suggests a partial reciprocity in this system. In addition, sparse numbers of labeled cerebellar fibers recross in the hypothalamus to distribute to homologous areas ipsilateral to the injection site. Subsequent to an injection in the medial cerebellar nucleus (NM), cell labeling was present in more rostral hypothalamic levels including the lateral and dorsal hypothalamic areas, the dorsomedial nucleus, around or in fascicles of the column of the fornix, and in the periventricular hypothalamic area. Although no fastigiohypothalamic fibers were seen in this study, on the basis of information available from the literature it is likely that such a connection exists in primates. In summary, hypothalamic projections to NM originated mainly from rostral to midhypothalamic levels, whereas those projections to the lateral three cerebellar nuclei came from mid and more caudal levels.

The existence of direct hypothalamic projections to cerebellar nuclei in M. fascicularis and of cerebellofugal projection to some hypothalamic centers indicates that circuitry is present through which the cerebellum may influence visceral functions. Furthermore, the fact that projections to NM versus the other cerebellar nuclei originate from somewhat different regions of the hypothalamus would suggest that the visceral functions modulated by each pathway is not the same.
Distribution of met‐enkephalin, leu‐enkephalin, substance P, neuropeptide Y, FMRFamide, and serotonin immunoreactivities in the optic tectum of the Atlantic salmon (Salmo salar L.)
Authors: Vecino Elena , Ekström Peter
Published: January 2005

The distribution of the neuropeptides methionine‐ and leucine‐enkephalins, substance P, FMRFamide, neuropeptide Y, and vasoactive intestinal peptide, as well as the biogenic amine serotonin was studied in the optic tectum of the Atlantic salmon by means of immunocytochemistry. Peroxidase‐antiperoxidase and indirect immunofluorescence methods were used to compare the differential laminar distribution of each of these substances. Nine parts of the optic tectum were selected for analysis on frontal sections: median, dorsolateral, and ventrolateral areas at rostral, medial, and caudal levels.

Methionine‐ and leucine‐enkephalin immunoreactive fibers were found in discrete sublayers in the following strata: stratum opticum, stratum fibrosum et griseum superficiale, stratum griseum centrale, stratum, and album centrale. Most of the substance P‐, serotonin‐, and vasoactive intestinal peptide‐immunoreactive fibers were found in the stratum album centrale, whereas the FMRFamide‐ and neuropeptide Y‐immunoreactive fibers were more or less randomly distributed within most of the strata of the optic tectum. Neuropeptide Y‐immunoreactive cell bodies were located in the stratum periventriculare.

We suggest an extrinsic origin for most of the immunoreactive fibers observed in the optic tectum, except for the neuropeptide Y‐immunoreactive fibers that probably originate in the periventricular neurons. Although retinal peptidergic input to the optic tectum has been proposed in other vertebrates, there is no evidence that any of the neuropeptidelike or serotonin immunoreactive fibers in the optic tectum of the salmon should be of retinal origin. Differences and similarities with the distribution of neuropeptides in the optic tectum in representatives of other vertebrate classes are discussed.
Failure of the subcallosal sling to develop after embryonic x‐irradiation is correlated with absence of the cavum septi
Authors: Schneider Bernard F. , Silver Jerry
Published: January 2005

During embryonic development of the rodent forebrain, a cavity normally appears at the midline just below the corpus callosum. This cavity, the cavum septi, is present in mice by gestational day 18, but is subsequently obliterated by growth of the septal nuclei and neuropil. After x‐irradiation of pregnant mice with 125r on gestational day 14.5, the cavum septi did not develop. This dramatic developmental abnormality was accompanied by delayed fusion of the septum, and a reduction in the population of subventricular cells that normally migrate to form a sling of cells extending from the medial aspect of the lateral ventricles to the midline. In normal animals formation of the cavum septi involves degeneration of this subcallosal sling of SV cells. Thus absence of the cavum after x‐irradiation may be due to the premature killing of subventricular cells before their migration toward the midline.