bluuebunny/crossref_metadata_2025 huggingface dataset:
Subclassification of neurons in the ventrobasal complex of the dog: Quantitative Golgi study using principal components analysis
Authors: Harpring J. E. , Pearson J. C. , Norris J. R. , Mann B. L.
Published: May 2005

The neuronal architecture of the ventrobasal complex (VB) in dog is examined in coronal and horizontal brain sections processed by Golgi‐ and Nissl‐staining methods. Presumed projection and intrinsic neurons are identified by differences in soma size and shape, dendritic branch pattern, the morphology and distribution of appendages, and the appearance of axons. Forty‐five projection neurons are examined by quantifying (1) soma cross‐sectional area, (2) dendritic field extent and shape, (3) appendages on the soma, primary dendrites, and in a defined major dendritic branch zone, and (4) location in the VB. When considered independently, each variable offers little evidence for separation into morphological classes. However, several of the variables have wide ranges and show significant correlation with other parameters. Using the multivariate descriptive methods of principal components analysis and cluster analysis, a separation of the projection neurons into three morphological classes designated as large, medium, and small neurons is indicated. The features most critical in distinguishing between the groups are, in descending order of importance: (1) dendritic field extent; (2) number of primary dendrites; (3) soma cross‐sectional area; (4) number of appendages per major branch point (MBP); (5) number of appendages on the soma; and, (6) number of appendages on the primary dendrites. Dendritic field shape and neuron location have little influence in determining classification.
Innervation of cat visual areas 17 and 18 by physiologically identified X‐ and Y‐ type thalamic afferents. I. Arborization patterns and quantitative distribution of postsynaptic elements
Authors: Freund T. F. , Martin K. A. C. , Whitteridge D.
Published: May 2005

Specific thalamic afferents to visual areas 17 and 18 were physiologically classified as X or Y type and injected with horseradish peroxidase (HRP). The axons were examined under the light microscope and were then processed for correlated electron microsocpy. X axons arborised in area 17 and in the border between area 17 and 18. The X axons all formed terminals throughout layer 6, but were heterogeneous in their distribution in layer 4. They either occupied the entire width of sublayers 4A and 4B or were strongly biased toward layer 4A. Y axons also arborised in layers 4 and 6, but in area 17 they did not form boutons in sublamina 4B. Some Y axons projected only to area 18; others branched and arborised in both areas 17 and 18. Only the collaterals of one X axon were found to enter area 18; all the others were restricted to area 17. Y axons formed three to four separate patches of boutons about 300–400 μm in diameter, while all but one X axon formed a single elongated patch. Y axons had thicker main branches (3–4 μm) than X axons (1.5–2.5 μm) at their point of entry to the cortex. The main axon trunks and their medium‐calibre collaterals were myelinated, but the preterminal segments were unmyelinated and studded with boutons. Each X or Y axon contacted about seven to ten somata, but Y axons made more contacts per soma (three to six) than did X axons (two to three). In addition to somatic synapses, both X and Y axons formed asymmetric (type 1) synapses on dendritic spines and shafts, with spines forming the most frequent targets (80%). Each Y bouton made, on average, 1.64 synapses in area 17 and 1.79 synapses in area 18, whereas each. X bouton made only 1.27 synapses on average. Although there are proportionally fewer Y axons than X axons entering area 17, the Y axons provide as many synapses as the X axons because of their larger arbors and multisynaptic boutons.
An analysis of the cellular localization of cytochrome oxidase in the lateral geniculate nucleus of the adult cat
Authors: Kageyama Glenn H. , Wong‐Riley Margaret
Published: May 2005

The distribution of cytochrome oxidase (C.O.) was examined in the normal adult cat lateral geniculate nucleus at the cellular and electronmicroscopic levels. The darker reactivity of the X‐ and/or Y‐receptive laminae (A, A1, magnocellular lamina C [Cm], and medial interlaminar nucleus [MIN]) compared with the lightly reactive W‐receptive parvicellular lamina C (Cp) indicates that there are pathway‐specific histochemical differences in the visual system of the cat. At the cellular level, darkly reactive large cells in the lateral geniculate nucleus (LGN) closely resemble class 1, Y‐cells, in relative size and distribution, thus indicating that C.O. histochemistry may be used as a functional marker for these cells. Perigeniculate neurons are also darkly reactive. Neuronal classes 2, 4, and 3 (presumed X‐cells, W‐cells, and/or interneurons) have moderate to lightly reactive perikarya. The darkly reactive neuronal classes tend to receive relatively stronger proximal excitatory synaptic input than do the less reactive neuronal classes. Since all neuronal classes appeared to have darkly (or moderately) reactive dendrites, C.O. reactivity must differ between dendrite and soma of some neuronal classes. At the electron‐microscopic level, distinct components of the neuropil tend to have specific levels of C.O. reactivity. The predominance of darkly reactive mitochondria in dendrites indicates that dendrites are metabolically very active. RLD and many F's, but few large axon terminals with round vesicles (RL) or small axon terminals with round vesicles (RS) profiles are darkly reactive, implying that specific classes of presynaptic structures are more active than others. Thus C.O. histochemistry may be useful for distinguishing not only functionally active neuronal classes such as Y‐cells and perigeniculate (PG) neurons from less active neuronal classes, but also functionally more or less active parts of the same neuron including its dendrites, axons, and/or axon terminals.
Cortical and subcortical afferent connections of the primate's temporal pole: A study of rhesus monkeys, squirrel monkeys, and marmosets
Authors: Markowitsch Hans J. , Emmans David , Irle Eva , Streicher Maria , Preilowski Bruno
Published: May 2005

The afferent connections of the primate's temporopolar cortex were investigated with the retrograde horseradish peroxidase technique. Old World and New World monkeys received small unilateral injections of horseradish peroxidase. These labeled cells in a number of cortical, thalamic, and brainstem regions and in a few further telencephalic and diencephalic regions.

Cortically, the neighboring areas of the inferior and superior temporal gyrus and the insula contained a considerable number of labeled cells. Furthermore, a substantial projection arose from the orbitofrontal and the frontopolar cortex. The cingulate gyrus contained only very few labeled cells. Interhemispherically, corticocortical connections arose mainly from temporal lobe areas. Labeled cells were seen in various regions of the basal forebrain and cells labeled only faintly in the lateral and basal accessory nuclei of the amygdala. The claustrum contained labeled neurons only in one rhesus monkey.

On the diencephalic level, the caudal medial portion of the medial pulvinar was the principal thalamic source of afferents to the temporopolar cortex. Furthermore, labeled cells were found in the neighboring, caudal part of the mediodorsal nucleus, within and along the nucleus limitans, in the medial geniculate nucleus, and in several nuclei of the nonspecific system. The fields of Forel, the zona incerta, and lateral and dorsomedial hypothalamic areas contained a few labeled cells.

Within the brainstem of the rhesus monkeys those regions projecting diffusely to the cortex contained a few labeled neurons. Furthermore, these brains had some labeled cells in the regions of the nuclei medialis annuli aqueductus, tractus mesencephalicus nervi trigemini, and trochlearis.

Although among the three species differences in the cortical and thalamic projection patterns were observed, the regions projecting most densely to the temporal pole were similar in principle. This statement holds in particular for cortical and thalamic sites. However, the greatest number of labeled cells was found in the rhesus monkey, a fact that cannot be attributed solely to the size of the horseradish peroxidase injections and the size of the brain, but that appears rather to represent a true species difference. From our results we conclude that the temporopolar cortex constitutes a cortical area necessary for effective affectional‐sensory integration.
Commissural neurons in layer III of cat primary auditory cortex (AI): Pyramidal and non‐pyramidal cell input
Authors: Code Rebecca A. , Winer Jeffery A.
Published: May 2005

The types of layer III neurons in cat primary auditory cortex (AI) projecting to the contralateral AI were studied with horseradish peroxidase or horseradish peroxidase conjugated to wheat germ agglutinin. Injections between the anterior and posterior ectosylvian sulci retrogradely labeled both pyramidal and non‐pyramidal somata in contralateral cortical layers III, V, and VI in AI, and in the ventral nucleus of the ipsilateral medial geniculate body. Three‐quarters (72%) of the retrogradely labeled cells were found in layer III and one‐quarter (28%) lay in layers V and VI. Every part of AI was innervated by commissural neurons. The topographical distribution of the labeled cells varied systematically. Injections in the caudal part of AI labeled cells in the caudal part of the opposite AI, while more rostral injections labeled cells in the contralateral, rostral AI. Injections covering the rostro‐caudal extent of AI labeled cells throughout the opposite AI. Each part of AI thus projects most strongly to a contralateral, homotypic area, and less strongly to other, adjacent sectors of AI.

The types of labeled cells were distinguished from one another on the basis of size, somatic and dendritic morphology, laminar distribution, and nuclear membrane morphology. Their somatodendritic profiles were compared to, and correlated with, those in Golgi‐impregnated material from adult animals. Among the pyramidal cells of origin were small, mediumsized, and large neurons, and star pyramidal cells. The non‐pyramidal cells of origin included bipolar and multipolar cells. Thus, at least six of the 12 kinds of neurons, as defined by morphological methods, participate in the interhemispheric pathway. Pyramidal cells comprised 65% of the cells of origin, 14% of the labeled cells in layer III were non‐pyramidal, and 21% of the neurons could not be classified.

It is unknown if these different types of commissural neurons have the same laminar or cytological targets in AI, or if they represent more than one functional or parallel pathway within AI. In any case, cytologically diverse layer III neurons contribute to the commissural system.
Species differences in electric organs of mormyrids: Substrates for species‐typical electric organ discharge waveforms
Authors: Bass Andrew H.
Published: May 2005

The organization of electric organs is described for the mormyrid fishes from Africa. The electric organ's spike‐generating cells or electrocytes are wafer‐shaped cells with a special geometry that relates to the number of phases and polarity of their pulsatile electric organ discharge (EOD) waveform. Six “families” of electrocytes are recognized on the basis of cell geometry. Each family includes species with EODs of similar polarity and phase number. Despite such similarities, there are still dramatic species differences in EOD waveforms for a given family that may further depend on specialized features of the electrocyte's excitable membranes. It is each species' particular electrocyte “profile” that must underlie the development of species‐specific and hormone‐dependent sex differences in the EOD waveforms.
Neuropeptide Y innervation of the hippocampal region in the rat and monkey brain
Authors: Köhler Christer , Eriksson Lars , Davies Stephen , Chan‐Palay Victoria
Published: May 2005

Using antibodies to neuropeptide Y (NPY) in combination with immunohistochemical techniques we have studied the distribution of cell bodies and nerve terminals containing NPY immunoreactivity (‐i) in the hippocampal region of rats and monkeys (cynomolgus). In colchicine‐pretreated rats a large number of NPY‐positive cells are present in all areas of the hippocampal region. The NPY‐i cells range in size from small (diameter across soma: 10–15 μm) to large (approximately 20 μm). Most of the NPY‐i cells are situated in the hilus, in the subgranular zone of the area dentata, and in the stratum oriens of Ammon's horn. A majority of these are polymorphic cells but cells of different morphology are present in these layers as well. These include small spheroid cells and dentate pyramidal basket cells that are distinct from the polymorphic cells in the subgranular zone. The subicular complex (e.g., the subiculum, pre‐, and parasubiculum) and the entorhinal area contain fewer NPY‐i cells than the rest of the hippocampal region. In the dorsal parts of the pre‐ and parasubiculuin numerous small cells are scattered throughout all layers, while in the entorhinal area the NPY‐stained cells are situated primarily in the deep layers (V and VI). In the ventral part of the lateral entorhinal area large multipolar and bitufted cells are found in layers II‐VI. In the untreated monkey brain NPY‐positive cells are found in the hilus of the area dentata and in the deep (IV through VI) layers of both the medial and lateral entorhinal area. Fewer NPY‐stained cells are present in the subicular complex and in the entorhinal area. In the monkey as well as in the rat, NPY‐stained cells are present in the angular bundle and in the alveus.

A dense network of NPY‐i fibers innervates the entire hippocampal region in both the rat and the monkey. The hippocampal NPY‐i preterminal processes are present primarily in stratum moleculare of Ammon's horn and in the outer one‐third of this layer in the area dentata. The NPY‐positive innervation of the dentate molecular layer is far more prominent in the monkey than in the rat brain. Numerous NPY‐stained fibers are scattered in other areas as well. In all retrohippocampal structures, and in particular the entorhinal area, the NPY‐i fibers form a massive network that innervates all layers to about the same extent, with the exception of the molecular layer, which is more densely innervated than the other layers.
The lamination and connectivity of embryonic cerebral cortex transplanted into newborn rat cortex
Authors: Chang Fen‐Lei F. , Steedman John G. , Lund Raymond D.
Published: May 2005

Sheets of frontal or occipital cerebral cortex were taken from embryonic day (E) 15 rat embryos and placed in shallow depressions made in the occipitoparietal region of newborn rats. These transplants developed normal patterns of lamination, which could be in an inverted orientation if the transplant itself was placed upside down. Irrespective of the cortical area of origin of the grafted tissue, the transplants consistently received projections from those host thalamic nuclei that were normally found to innervate the adjacent host cortex. This indicates that immature cortical tissue, up to at least E15, may not contain the information necessary to define the specific thalamocortical connections characteristic of individual areas. On the contrary, the observed input pattern may be the result of sprouting of fibers that normally innervated host cortical regions adjacent to the transplant. Similarly, callosal afferents to transplants seemed to be a direct extension of the callosal input to the host cortex immediately beneath the transplant.

Results from HRP studies of callosal connections indicated that transplant efferents to the contralateral cortex are smaller in magnitude than their afferents. This may be related to the superficial location of the transplants, which may limit the access transplant efferents have to the white matter.

This study suggests that, while the cortical lamination is largely determined intrinsically, the innervation of the cortex is influenced by the context in which it develops.
Cellular degeneration and synaptogenesis in the developing retina of the rat
Authors: Horsburgh Gwynn M. , Sefton Ann Jervie
Published: May 2005

We have investigated the time course and magnitude of cellular degeneration in the ganglion cell layer and the presumptive amacrine and bipolar regions of the inner nuclear layer during the development of the retina in the rat. Pyknotic profiles are present in the ganglion cell layer during the first 2 postnatal weeks, reaching peak numbers during the first 4 postnatal days (corresponding to the time of greatest loss of ganglion cells and their axons: Potts et al., ′82; Lam et al., ′82; Perry et al., ′83). Two observations suggest that the majority of pyknotic profiles present in the ganglion cell layer during the second postnatal week are not ganglion cells. First, following injection of kainic acid into one superior colliculus, degenerating ganglion cells in the contralateral retina are cleared within 24–48 hours. Therefore, since most ganglion cell and axon loss occurs within the first postnatal week, few of the pyknotic profiles present in the second week are likely to be ganglion cells. Second, the time course of cellular degeneration in the ganglion cell layer during the second postnatal week follows a very similar pattern to that seen in the presumptive amacrine sublayer of the inner nuclear layer. Such a correspondence suggests that two phases of cell death occur in the ganglion cell layer: during the first postnatal week the majority of dying cells are ganglion cells, and in the second, most cell death is due to a loss of displaced amacrine cells.

In the inner nuclear layer pyknotic profiles are most numerous in the presumptive amacrine region on postnatal days 6 and 7, and in the presumptive bipolar region on day 10. Synaptogenesis in the inner plexiform layer occurs later but reflects the order of cell death. Thus, conventional (presumed amacrine) synapses were first observed on day 11 and synaptic ribbons (indicative of bipolar synapses) on day 13. These observations suggest that amacrine and bipolar cells initiate synapses only after their numbers have stabilized.
Stratified distribution of synapses in the inner plexiform layer of primate retina
Authors: Koontz Margaret A. , Hendrickson Anita E.
Published: May 2005

Distributions of bipolar (B) and amacrine (A) synapses and postsynaptic ganglion cell (G) dendritic profiles in the inner plexiform layer (IPL) were analyzed in EM montages of monkey central and human foveal and peripheral retinae. Synapses and profiles were counted and plotted for each 5% interval of IPL, with 0% at the inner edge of the inner nuclear layer and 100% at the outer edge of the ganglion cell layer. In monkey and human retinae, both A and B synapses occur throughout the IPL, but the ratio of A to B synapses varies from 2:1 to more than 6:1.

In the monkey central retina, four bands of A conventional synapses are concentrated at 15, 35, 60, and 80% depth. In the human foveal slope, there are two main A bands at 45 and 85%, whereas in the human periphery, there are five bands at 15, 35, 60, 75, and 90%. In both species, A processes containing large dense‐core vesicles are concentrated in three bands at 10–20, 50, and 80–90% depth, corresponding to previously described levels of peptides, dopamine, and GABA. B ribbon synapses are distributed fairly evenly throughout the IPL, with a suggestion of four broadly overlapping bands. Most B ribbons are presynaptic to one A and one G (B → A/G). In the human, there are significantly more B dyads with postsynaptic G's (B → A/G, B → G/G) in the fovea (91%) than in the periphery (66%), implying greater A cell processing peripherally. Also in the human, B terminals containing glycogenlike granules are concentrated in the outer half of the IPL, with agranular terminals in the inner half. Our results demonstrate multiple strata containing different types of synaptic contacts in primate IPL.
Changes of neurotensinlike immunoreactivity in the striatum of the cat after intrastriatal injection of kainic acid
Authors: Sugimoto Tetsuo , Itoh Kazuo , Yasui Yukihiko , Kamiya Hiroto , Uemura Yoshihiko , Mizuno Noboru
Published: May 2005

In the course of our study on the effects of kainic acid (KA) on neuropeptidelike immunoreactivity in striatal neurons, it was found that neurotensinlike immunoreactivity (NT‐LI) became visible immunohistochemically in cell bodies of some striatal neurons after injecting KA stereotaxically into the head of the caudate nucleus (Cd) of the cat. The adult cats injected with KA were allowed to survive for 1–56 days, and their brains were examined by the indirect immunoperoxidase method. In the intact Cd, NT‐LI was observed in axonal elements that accumulated to form irregularly shaped patches and displayed a discrete island‐and‐matrix pattern. At the site of KA injection, where neuronal cell loss and gliosis were produced, NT‐LI almost disappeared by the fourth day after KA injection. In parallel with these changes, many neuronal cell bodies with NT‐LI became visible in striatal regions surrounding the site of KA injection. Most of these neuronal cell bodies that showed NT‐LI were medium‐sized and extended thick dendrites with spines; spiny processes were rarely seen on the cell bodies. On the other hand, when a lesion was placed in the head of the Cd by thermo‐coagulation, no NT‐LI could be seen in cell bodies of striatal neurons. Thus it was presumed that NT‐LI in cell bodies of medium‐sized, spiny neurons of the cat striatum might be at a low level under normal conditions but enhanced in cell bodies of the neurons that survived the KA injections.
Radioautographic evidence for slow astrocyte turnover and modest oligodendrocyte production in the corpus callosum of adult mice infused with 3H‐thymidine
Authors: McCarthy G. F. , Leblond C. P.
Published: May 2005

To find out whether glial cells proliferate in the corpus callosum of adult mice, two series of experiments were carried out. The first one made use of 9‐month‐old “aged” male mice. Some of them were given 3H‐thymidine as a 2‐hour pulse to examine which cells became labeled and, therefore, had the ability to divide. Others were sacrificed after a continuous infusion of 3H‐thymidine for 30 days to examine whether the label would then appear in different cells. In other aged animals, the 30‐day infusion was followed by 60 or 180 days without 3H‐thymidine to determine whether cells retained or lost their label with time. A second series of experiments was carried out in 4‐month old “young adult” male mice to seek confirmation of the main conclusions.

Following the 3H‐thymidine pulse given to aged mice, only immature glial cells were labeled. After a 30‐day infusion, 12.1% astrocytes and 1.1% oligodendrocytes were labeled, so that the net daily addition rate of astrocytes averaged 0.4% and of oligodendrocytes, 0.04%. In young adult mice, the rate after a 7‐day infusion averaged 0.9% for astrocytes and 0.08% for oligodendrocytes. However, when the 30‐day infusion into aged mice was followed by 60 and 180 days without 3H‐thymidine, the labeled astrocytes decreased to 5.3% and 0%, respectively, whereas the number of labeled oligodendrocytes did not change significantly.

The interpretation of the results is that the immature cells present in the corpus callosum of mice continue dividing throughout life and their progeny give rise to astrocytes and oligodendrocytes. In the case of astrocytes, the production of new cells occurs in parallel with a loss, so that the astrocyte population turns over. In the case of oligodendrocytes, there is a small production of new, apparently stable cells.
Characterization of transient cortical projections from auditory, somatosensory, and motor cortices to visual areas 17, 18, and 19 in the kitten
Authors: Dehay Colette , Kennedy Henry , Bullier Jean
Published: May 2005

We have examined the anatomical features of ipsilateral transient cortical projections to areas 17, 18, and 19 in the kitten with the use of axonal tracers Fast Blue and WGA‐HRP. Injections of tracers in any of the three primary visual areas led to retrograde labeling in frontal, parietal, and temporal cortices. Retrogradely labeled cells were not randomly distributed, but instead occurred preferentially at certain loci. The pattern of retrograde labeling was not influenced by the area injected. The main locus of transiently projecting neurons was an isolated region in the ectosylvian gyrus, probably corresponding to auditory area A1. Other groups of transiently projecting neurons had more variable locations in the frontoparietal cortex.

The laminar distribution of neurons sending a transient projection to the visual cortex is characteristic and different from that of parent neurons of other cortical pathways at the same age. In the frontoparietal cortex, transiently projecting neurons were located mainly in layer 1 and the upper part of layers 2 and 3. In the ectosylvian gyrus, nearly all the neurons are located in layers 2 and 3. In addition, a few transiently projecting neurons are found in layer 6 and in the white matter. Transiently projecting neurons have a pyramidal morphology except for the occasional spindle‐shaped cell of layer 1 and multipolar cells observed in the white matter.

Anterograde studies were used to investigate the location of transient fibers in the visual cortex. Injections of WGA‐HRP at the site of origin of transient projections gave rise to few retrogradely labeled cells in areas 17, 18, and 19, demonstrating that transient projections to these areas are not reciprocal. Although labeled axons were found over a wide area of the posterior cortex, they were more numerous over certain regions, including areas 17, 18, and 19, and absent from other more lateral cortical regions. Transient projecting fibers were present in all cortical layers at birth. Plotting the location of transient fibers in numerous sections and at all ages showed that these fibers are not more plentiful in the white matter than they are in the gray matter. We found no evidence that the white/gray matter border constituted a physical barrier to the growth of transient axons.

Comparison of the organization of this transient pathway to that of other transient connections is discussed with respect to the development of the cortex.
Distribution of cells containing mRNAs encoding substance P and neurokinin B in the rat central nervous system
Authors: Warden Marjorie K. , Young W. Scott
Published: May 2005

The family of tachykinins includes the neuropeptides substance P, neurokinin A, and neurokinin B. The distribution of substance P in the central nervous system has been studied immunohistochemically but the lack of specific antibodies has prevented similar studies of neurokinin B. Recent molecular genetics techniques have revealed the sequences for the complementary DNAs that code for the substance P and neurokinin B precursors. These results have permitted the design of specific probes to differentiate between substance P and neurokinin B transcripts by using in situ hybridization histochemistry. Our probes, 48‐base synthetic oligodeoxynucleotides labeled with 35S revealed extensive and distinct patterns of cell labeling for both substance P and neurokinin B throughout the rat central nervous system.

The distribution of substance‐P‐mRNA‐containing cells that we observed confirmed and extended previous immunocytochemical descriptions. Cells containing transcripts for either tachykinin were present in the neocortex, hippocampus, olfactory bulb and associated areas, caudate‐putamen, hypothalamus, medial habenula, superior colliculus, central gray, and dorsal horn of the spinal cord. However, their distributions within these areas were usually quite different. Other areas contained only one tachykinin cell type: e.g., the nucleus of the lateral olfactory tract contained only neurokinin B cells whereas the raphe nuclei had only substance P cells. This study demonstrates the sensitivity and specificity of in situ hybridization histochemistry for mapping peptidergic neurons and lays the foundation for further investigations of the roles of these two tachykinins in the central nervous system.
Trigeminal alveolar nerve of the lower jaw in the cichlid Tilapia mariae: Evidence for continual axon generation and presence of exceptionally small myelinated axons
Authors: Hildebrand C. , Wiberg J. , Holje L.
Published: May 2005

Cross sections from the trigeminal alveolar nerve of the lower jaw in the cichlid Tilapia mariae were examined by electron microscopy. The nerve fibers are arranged in groups with a core of unmyelinated and small myelinated axons, surrounded by myelinated axons of varying sizes. The core contains large bundles of unmyelinated axons collectively ensheathed by circumferentially located Schwann cells, as well as smaller bundles of unmyelinated axons partly separated from each other by Schwann cell processes. Among the unmyelinated axons, occasional scattered profiles resembling growth cones are seen. The total number of axons in this tooth‐related nerve increases from approximately 1,500 to 5,000, as the animals grow in length from 4.5 to 21.5 cm. Some 24–49% of the axons are unmyelinated. The myelinated axons have maximum diameters of 1.0–3.0 μm, depending on body size. Most myelinated axons have diameters less than 1.0 μm and the smallest ones reach down to 0.3 μm. These results show that there is a continual addition of axons to the alveolar nerve of the lower jaw in Tilapia mariae and that the critical diameter for myelination in this peripheral nerve is similar to that typically found in the mammalian CNS.
Morphology of neurons in the basal forebrain nuclei of the rat: A Golgi study
Authors: Dinopoulos A. , Parnavelas J. G. , Uylings H. B. M. , van Eden C. G.
Published: May 2005

The neuronal cell types and their morphology in the nucleus basalis (NB), in the horizontal and vertical limbs of the diagonal band of Broca (NHL and NVL), and in the medial septal nucleus (MSN) were examined in Golgi‐impregnated material. Cells appeared as multipolar or oligopolar and displayed a variable dendritic morphology; their somata varied considerably both in shape and size. The dendrites of most cells were restricted within nuclear boundaries, although occasionally neurons located near boundaries, particularly cells in NHL, extended dendritic arbors into neighboring areas. Axons were rarely seen, but when they were found they were generally not impregnated beyond the initial segment and displayed no apparent preferential direction.

Three types of cells common to each of the 4 nuclear groups could be identified on the basis of soma shape and dendritic form. The first type included large multipolar neurons with triangular or polygonal perikarya and typically 3–5 dendrites emerging from the poles of each cell. These cells were especially numerous in NB, NHL, and NVL, but were much less frequent in MSN. The second type comprised medium‐sized cells with round or oval somata and a small number, usually 2–3, of dendrites. They constituted a large percentage of the cell population in MSN, but were also encountered in NHL and NVL as well as in NB. The third type consisted of cells with fusiform or spindle‐shaped somata with usually single dendrites emanating from each pole of the cell. A rare but distinct type of spindleshaped neuron with dendrites bearing a rich complement of long and thin appendages was observed mainly in the ventral border of NHL.

The present observations suggest that although the proportions and sizes of the 3 types of neurons vary between the 4 nuclei, neurons throughout the basal forebrain share common morphological characteristics.
Development of intracerebral dopaminergic grafts: A combined immunohistochemical and autoradiographic study of its time course and environmental influences
Authors: Abrous N. , Guy J. , Vigny A. , Calas A. , Moal M. Le , Herman J. P.
Published: May 2005

The aim of the study was to obtain a description of some aspects of the development of intracerebral dopaminergic grafts, namely, the time course of the glial reaction and its relation to cell division on one hand, and the development of graft‐originated innervation and its dependence on adequate matching of the implanted neurons and target site on the other hand. Cell suspensions obtained from the mesencephalon or hypothalamus of embryonic day (ED) 14 rat embryos were implanted into the striatum or lateral hypothalamus of adult rats following the destruction of the nigrostriatal system of the hosts. Animals were sacrificed at different postimplantation times, and the development of the graft was followed by immunohistochemistry by using antisera directed against tyrosine hydroxylase (TH) or glial fibrillary acidic protein (GFA). Furthermore, the existence of cell division at various times following implantation was examined by performing autoradiography on immunostained sections after prior intraventricular administration of 3H‐thymidine to the host. The first stage of the development of intracerebral grafts was characterized by the existence of intense cell division within the grafted tissue, lasting about 2 weeks, and also in the host tissue surrounding the graft, lasting only about 6 days. The cell division in the host tissue was paralleled by the existence of a strong glial reaction which, however, did not extend into the graft itself. Glial reaction in the host tissue gradually decreased at later times and disappeared by 4 weeks postimplantation without leaving behind a noticeable glial scar. The graft itself was, however, transiently filled with a population of reactive astroglial cells between 3 and 6 weeks postimplantation. Within grafts of mesencephalic tissue located in the striatum TH‐positive neurons were distributed evenly at short times postimplantation (2–6 days). At later time a compartmentation could be observed, with TH‐positive neurons being aligned along the graft‐host interface or clustered within the graft itself. Innervation of the host tissue by TH‐positive fibers increased between 1 and 6 weeks postimplantation. On the other hand, no compartmentation and reinnervation of surrounding host tissue was observed for intrahypothalamic grafts of mesencephalic tissue or intrastriatal grafts of hypothalamic tissue. This last observation indicates that adequate matching of implanted neurons and target tissue plays an important role in the development of intracerebral dopaminergic grafts.
New view of the organization of the pulvinar nucleus in Tupaia as revealed by tectopulvinar and pulvinar‐cortical projections
Authors: Luppino G. , Matelli M. , Carey R. G. , Fitzpatrick D. , Diamond Irving T.
Published: May 2005

The projections of the superficial layers of the superior colliculus to the pulvinar nucleus in Tupaia were reexamined by injecting WGA‐HRP into the tectum. The main result was finding two different patterns of terminations in the pulvinar nucleus: a zone remote from the lateral geniculate nucleus, which occupies the dorsomedial and caudal poles of the pulvinar nucleus, was almost entirely filled with terminals in every case irrespective of the location of the injection site; and a second division of the pulvinar nucleus, adjacent to the lateral geniculate nucleus, contained irregular patches—much more densely populated—and the distribution of patches varied from case to case. We call the first projection „diffuse”︁ and the patchy projection „specific.”︁ Next we injected several divisions of the extrastriate visual cortex to find the cortical target of each pathway. The diffuse path terminates in the ventral tenporal area (Tv). The specific path terminates in the dorsal temporal area (Td) and area 18. We speculated about the significance of the two pathways: the specific path may be responsible for the preservation of vision after removal of the striate cortex; the diffuse path may have an important place in the evolution of the visual areas of the temporal and occipital lobe. We argued that the target of the diffuse path is in a position to relate limbic and visual impulses and relay the product of such integration to the other visual areas, striate as well as extrastriate cortex.
Origins of descending projections to the medulla oblongata and rostral medulla spinalis in the urodeleSalamandra salamandra (amphibia)
Authors: Naujoks‐Manteuffel Christiane , Manteuffel Gerhard
Published: May 2005

Descending projections to the medulla oblongata and rostral medulla spinalis have been examined in the urodele Salamandra salamandra with retrograde horseradish peroxidase tracing. Ipsilateral projections originate from the striatum and the nucleus ventrolateralis thalami and reach the medulla oblongata. The ipsilateral nucleus praeopticus magnocellularis reaches the medulla spinalis. The rostral part of the nucleus tuberculi posterioris projects to the ipsilateral medulla oblongata; its caudal part projects further caudally. Tectal efferents and the efferents of the nucleus praetectalis profundus project bilaterally, the nucleus praetectalis superficialis, nucleus mesencephalicus nervi trigemini, torus semicircularis, nucleus Darkschewitsch, and nucleus fasciculi longitudinalis medialis project ipsilaterally to the medulla oblongata. The nucleus mesencephalicus nervi trigemini, nucleus fasciculi longitudinalis medialis, and tectal efferents reach the rostral medulla spinalis. The nucleus ruber projects mainly via the contralateral dorsolateral funiculus to the medulla spinalis. A largely crossed medullary projection arises in the nucleus dorsalis tegmenti pars anterior, a bilateral projection arises in the nucleus dorsalis tegmenti pars posterior, and an ipsilateral projection arises in the nucleus ventralis tegmenti pars anterior. Cerebellar and statoacoustic efferents descend to the medulla spinalis. The nucleus reticularis isthmi, superior, medius and inferior as well as the nucleus raphes exhibit spinal trajectories. The nucleus vestibularis magnocellularis projects bilaterally, the nucleus vestibularis medialis projects ipsilaterally spinalward. The supposed nucleus descendens nervi trigemini descends mainly contralaterally. A small spinal projection arises in the nucleus tractus solitarii.

The results indicate that salamander brains display elaborate descending connections which are similar to those in other vertebrates despite their scarcely differentiated neuronal cytoarchitecture.
Central distribution of subdiaphragmatic vagal branches in the rat
Authors: Norgren Ralph , Smith Gerard P.
Published: May 2005

In the rat, the subdiaphragmatic vagus nerves (SDX) have five major branches—the right gastric, the left gastric, the coeliac, the accessory coeliac, and the hepatic. Although these branches innervate more than the organs after which they are named, some mediate specific behavioral functions. In addition to the SDX trunk, the central stump of each of these branches was incubated in horseradish peroxidase (HRP) for 6 hours in anesthetized rats. After processing the vagal ganglia, pons, medulla, and upper cervical spinal cord of each preparation, the sections were examined for both retrogradely and anterogradely transported HRP reaction product. When only one nerve had been incubated, retrogradely labeled neurons were confined primarily to the ipsilateral ganglion, medulla, and spinal cord. Within the brain, a few labeled neurons occurred within the nucleus ambiguus (NA) and the reticular formation caudal to the NA, but the vast majority appeared in the dorsal motor nucleus of the vagus (DMX). The axons of most labeled neurons in the NA distributed in the gastric branches; those from cells caudal to the NA, probably distributed in the coeliac branch. Most labeled DMX cells also distributed with the gastric branches. Those on the lateral tip of the right DMX, however, had axons in the coeliac branch; those on the left DMX tip, in the accessory coeliac. After incubation of the SDX trunk, anterograde HRP reaction product occurred in the caudomedial nucleus of the solitary tract (NST) just rostral and subjacent to the area postrema (AP). Unlike the retrograde label, anterograde reaction product was bilateral, but always weaker contralaterally. Within the SDX distribution, the afferent axons from the gastric branches exhibited one pattern of termination; those from the coeliac, accessory coeliac, and hepatic branches, another. The gastric branch distributions began dorsolaterally in the SDX termination zone and continued caudally beneath the AP. Immediately subjacent to the AP, gastric branch terminals were never dense and the entire distribution faded at the level of the obex. The coeliac and accessory coeliac distributions began dorsomedially within the SDX termination zone and intensified caudally in a thin band immediately subjacent to the AP. The densest label was associated with the caudal half of the AP, but the distribution thinned rapidly caudal to the obex. The hepatic distribution was similar to that of the coeliac branches but never achieved similar density. Physiological and behavioral data correlate with the anatomical picture in that the efferent functions appear to be more densely localized than the afferent functions.
Oxytocinergic innervation of the brain of the garden dormouse (Eliomys quercinus L.)
Authors: Hermes M. L. H. J. , Buijs R. M. , Masson‐Pévet M. , Pévet P.
Published: May 2005

The oxytocinergic innervation of the brain of the garden dormouse (Eliomys quercinus L.) was studied by means of immunocytochemistry. In contrast to the sparse oxytocin innervation of the rat forebrain, dense fibre networks in various cortical and limbic brain areas were demonstrated in this animal. These include, e.g., the prefrontal cortex, the claustrum, the septum, and the hippocampus. A very dense innervation was also seen in the caudal regions of the garden dormouse brain; these regions are already known to have a relatively dense oxytocin fibre network in the rat.

A dense innervation of oxytocin fibres is seen in several brain regions which, in the rat, have oxytocin binding sites but no visible oxytocin innervation. This discrepancy suggests that the differences in the oxytocinergic innervation of these two rodent brains may be due to an oxytocin system in the rat brain that is more difficult to detect immunocytochemically.
Development of β1 and β2 adrenergic receptors in baboon brain: An autoradiographic study using [125I]iodocyanopindolol
Authors: Slesinger Paul A. , Lowenstein Pedro R. , Singer Harvey S. , Walker Lary C. , Casanova Manuel F. , Price Donald L. , Coyle Joseph T.
Published: May 2005

[125I]iodocyanopindolol (ICYP) autoradiography was used to investigate the temporal development and distribution of β1 and beta;2 receptors in brains of baboons at ages embryonic day 100 (E100), full‐term gestation (E180), and 3 years. In all brain regions examined, with the exception of the hippocampus, binding to β1 receptors exceeded that to β2 receptors. The highest densities of ββ1 receptors were found in the caudate nucleus, putamen, globus pallidus, substantia nigra, and cerebral cortex; intermediate receptor densities were observed in most nuclei of thalamus, and the lowest concentrations were in the hippocampus. At E100, β1 receptors were identified in the striatum, globus pallidus, and thalamus. During maturation, the number of β1 receptors declined in cortical areas but increased in the head of the caudate and putamen. Significant differences in the developmental distribution of β1 receptors during development were also detected: at E100 and E180 β1 receptors appeared as patches in the caudate and putamen, but by 3 years of age they were more homogeneously distributed in both regions; changes also occurred in the distribution of binding within cortical layers. Autoradiograms of [125I]ICYP and [3H]mazindol binding show overlapping patches of labeling in the E180 striatum, suggesting a possible developmental association between β receptors and dopamine high‐affinity uptake carrier sites. This study demonstrates that noradrenergic receptors in the primate forebrain undergo significant developmental reorganization with regional variations.
Acetylcholinesterase fiber staining in the human hippocampus and parahippocampal gyrus
Authors: Green Robert C. , Mesulam M‐Marsel
Published: May 2005

The AChE fiber distribution within the human hippocampus and parahippocampal gyrus was studied in order to provide normative data for the examination of cholinergic fiberarchitecture in human pathology and to clarify the cytoarchitectonic organization of these structures. A modification of the Koelle method was used to stain temporal lobe serial sections from 6 neurologically normal human brains collected at autopsy.

The hippocampal formation contains some of the densest staining of any cortical area. Regions with the heaviest concentrations of AChE fibers include a thin band along the inner edge of the molecular layer of the dentate gyrus (ml‐DG) and parts of the CA2, CA3, and CA4 sectors of Ammon's horn. Staining is of intermediate intensity in the CA1 region. The subiculum (S) is more lightly stained than the CA fields. Staining in the parahippocampal gyrus is generally less dense than in the hippocampal formation. The most conspicuous feature of the human entorhinal cortex (EC) is the AChE‐rich fiber patches seen overlapping the stellate cell islands in layer II. An additional band of relatively dense AChE staining is identified in layers IV‐V. Prominent AChE‐rich polymorphic neurons are present within the hilum of the dentate gyrus.

The CA1/subiculum transition in Nissl preparation is characterized by an oblique interdigitation of CA1 cells. The transition from EC to prorhinal cortex occurs along the medial bank of the rhinal sulcus and is characterized by a band of AChE staining, which slopes obliquely away from layer II until it joins an intermediate pyramidal cell layer. Some comparisons with AChE staining in the monkey were made. The monkey has a similar pattern except in DG, where the intensely AChE staining band along the inner ml‐DG is thicker and much more prominent. In comparison to the human, the monkey has more conspicuous AChE staining in the parasubicular region.