bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the rhesus monkey retina. I. Emergence of the inner plexiform layer and its synapses
Authors: Nishimura Yozo , Rakic Pasko 
Published: May 2005

AbstractThe emergence and differentiation of the inner plexiform layer (IPL) and the establishment of its synapses were analyzed in retinae of 18 rhesus monkeys ranging in age from the 55th embryonic day (E55) to 10 years. The IPL becomes recognizable by E65 as a thin acellular zone consisting of immature neurites and growth cones scattered within large extracellular spaces. In each specimen, apposing paired membrane specializations were classified as junctions without synaptic vesicles, conventional synapses, ribbon synapses, or gap junctions. Initially, at E65, the IPL consists of variety of immature cell processes that are interconnected exclusively by junctions without synaptic vesicles, at a density of 4.7/100 μm2. By E73, the IPL becomes more distinct and wider and contains 7.8 such junctions/100 μm2. Conventional synapses develop by the addition of vesicles to initially vesiclefree junctions. The first conventional synapses appear at E78. They increase in density from 1.5 to 3.2/100 μm2 between E78 and E84 and reach a density of 7.9/100 μm2 by E99. A rapid burst in synaptogenesis occurs in the IPL between E99 and E114; a density of 16.5/100 μm2 is reached, mainly due to accretion of conventional synapses.Ribbon synapses first become recognizable at E99, almost 3 weeks after the emergence of conventional synapses. By E114 they account for about 7% of all synaptic contacts in the IPL. The rate of synaptogenesis slows down during the last quarter of gestation; the adult level of about 24 contacts/100 μm2 is reached between E130 and E149. Of these, 72.2% are of conventional type, 15.4% are ribbon synapses, and 12.4% are junctions without vesicles. However, in the adult the density of junction without vesicles is only about one‐half that found at E149. Gap junctions are absent during the initial and rapid phases of synaptogenesis; they appear abruptly, between E130 and E149, only after the density of chemical synapses in the IPL has reached the adult level.In the rhesus monkey, synaptogenesis begins several weeks later in the IPL than in its primary targets–the dorsal lateral geniculate nucleus and the superior colliculus (Hendrickson and Rakic, '77; Cooper and Rakic, '83). However, the rapid increase in density of conventional synapses in the IPL coincides with the segregation of retinal projections from right and left eyes in the geniculate nucleus (Rakic, '76) and with the elimination of the large surplus of retinal ganglion cell axons (Rakic and Reley, '83).
Patterns of primary afferent termination in the external cuneate nucleus from cervical axial muscles in the cat
Authors: Bakker D. A. , Richmond F. J. R. , Abrahams V. C. , Courville J. 
Published: May 2005

AbstractUsing the method of transganglionic transport of horseradish peroxidase (HRP), the distribution of primary afferent projections was examined in the external cuneate nucleus (ECN) from different muscle groups in the forequarter of the cat. The terminal zones of afferent fibers from three shoulder muscles–clavotrapezius, acromiotrapezius, and spinotrapezius–were compared to projections from suboccipital muscles, dorsal neck extensors, and muscles of the proximal forelimb. Each muscle group had a labelled terminal zone that occupied a different subvolume of the ECN. The zone labelled from trapezius muscles formed a continuous column in the ECN running from the caudal pole of the nucleus to a level 3.0 mm rostral to the obex. Terminal zones of suboccipital muscles and dorsal neck extensors formed longer columns that extended into the most rostral tip of the ECN, while those of proximal forelimb muscles formed shorter columns confined to the caudal two‐thirds of the ECN. At comparable cross‐sectional levels in the caudal and middle portions of the ECN, terminal zones from proximal limb muscles were located most dorsomedially, while those from shoulder muscles, dorsal neck muscles, and suboccipital muscles were located in progressively more ventral and lateral regions. The subvolume of the ECN occupied by projections from cervical axial muscles was estimated to be more than 40% of the volume of the nucleus, suggesting that the ECN has a major role in the transmission of sensory information from axial musculature to the cerebellum. Following exposure of all muscle nerves to tracer, a second labelled zone was also identified close to the ECN in the descending vestibular nucleus at transverse levels 2.0–3.0 mm rostral to the obex. Here, reaction product was concentrated around a circumscribed collection of medium‐sized, multipolar cells.
Efferent connections of the prelimbic (area 32) and the infralimbic (area 25) cortices: An anterograde tracing study in the cat
Authors: Room Peter , Russchen Fokje T. , Groenewegen Henk J. , Lohman Anthony H. M. 
Published: May 2005

AbstractThe projections from the caudal part of the medial frontal cortex, encompassing the prelimbic area (PL) and the infralimbic area (IL) (Brodmann's areas 32 and 25, respectively), were studied in the cat with the anterograde autoradiographic tracing technique. The results indicate that the projection fields of IL, in contrast to those of PL, are restricted almost exclusively to limbic structures.Whereas the major thalamic projections from PL reach the mediodorsal, anteromedial, and ventromedial nuclei, the medial part of the lateral posterior nucleus, and the parataenial and reticular nuclei, and weak projections from this area are directed to the nucleus reuniens and other midline nuclei, the nucleus reuniens is the major thalamic termination field of fibers arising from IL. Cortical areas that are reached by fibers originating in PL and, to a lesser degree, also in IL, include more rostral prefrontal areas (areas 8, 6, and 12), the agranular insular, and the rostral perirhinal cortices. In contrast, cortical areas that are more strongly related to IL include the cingulate, retrosplenial, caudal entorhinal, and perirhinal cortices and the subiculum of the hippocampal formation. Another prominent output of PL concerns projections to an extensive medial part of the caudate nucleus and the ventral striatum, whereas fibers from IL only distribute most ventrally in the striatum. In the amygdaloid complex, fibers from PL were found to reach the basolateral, basomedial, and central nuclei, and fibers from IL to distribute to the medial and central nuclei. PL furthermore projects to the claustrum and the endopiriform nucleus. Other structures in the basal forebrain, including the medial septum, the nuclei of the diagonal band, the preoptic area, and the lateral and dorsal hypothalamus are densely innervated by IL and only sparsely by PL. With respect to more caudal parts of the brainstem, projections from PL and IL appeared to be essentially similar. They reach the ventral tegmental area, the periaqueductal gray, the parabrachial nucleus, and in cases of PL injections were followed as far caudally as the pons.
Peptidergic innervation of insect skeletal muscle: Immunochemical observations
Authors: Witten Jane L. , O'Shea Michael 
Published: May 2005

AbstractProctolin (Arg‐Tyr‐Leu‐Pro‐Thr) is a pentapeptide present in the hindgut or proctodeum of the cockroach Periplaneta americana where it may be a transmitter. Its widespread distribution among peripherally projecting neurons in the CNS (Bishop and O'Shea, '82) suggested that proctolin's motor function is not restricted to the hindgut, but has a variety of peripheral targets. This idea was further supported when proctolin was localized to an identified skeletal motoneuron, the slow coxal depressor, where it acts as a cotransmitter (O'Shea and Bishop, '82; Adams and O'Shea, '83). Our objective was to investigate the proctolinergic innervation of a variety of skeletal muscles of the cockroach Periplaneta americana. We used immunohistochemical and radioimmunochemical methods to map the distribution of proctolin immunoreactivity. This survey revealed that a subpopulation of skeletal muscles are innervated by proctolinergic motoneurons. The anatomical features of the peptidergic innervation and the levels of proctolin‐like immunoreactivity of one muscle group, the coxal depressor system, are here described in detail. The source of the proctolin innervation to the metathoracic coxal depressor group is identified as the slow coxal depressor motoneuron. The results of a survey of fast and slow skeletal muscles revealed that proctolin is associated with slow motor function. The functional implications of the association of a peptide with motoneurons are discussed in relationship to the organization of the insect motor pool.
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

AbstractThe 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

AbstractSpecific 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractUsing 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.