bluuebunny/crossref_metadata_2025_split huggingface dataset:
An enzyme tracer study of the organization of the somatic motor center for the innervation of different muscles of the tongue: Evidence for two sources
Authors: Chibuzo Gregory A. , Cummings John F. 
Published: January 2005

AbstractThe hypoglossal nucleus has been described as the sole ipsilateral source of somatic motor innervation of the lingual and geniohyoideus muscles (Streeter, 1940; Barnard, 1940; Crosby et al., 1962; Watkins, 1978; Jenkins, 1978). In this study microliter amounts of 30% solution of horseradish peroxidase (HRP) were injected into intact but surgically isolated canine genioglossus, hyoglossus, styloglossus, geniohyoideus, and intrinsic lingual muscles. All injections were confined to the left half of the tongue, and the right half served as control. The HRP injections resulted in ipsilateral labeling of hypoglossal neurons with the exception of the injections into the genioglossus muscle, which labeled this nucleus bilaterally. Surprisingly, a few neurons associated with the ventromedial aspect of the caudal pole of the ipsilateral facial motor nucleus also labeled after injections of lingual muscles. The somatotopic representation of the geniohyoideus and lingual muscles within the hypoglossal nucleus suggested that those muscles known to originate from the same or related primodia labeled in the same or closely related hypoglossal subnuclei. The presence of labeled neurons associated with facial motor nucleus supported the hypothesis (Langman, 1975) of a possible dual origin of lingual muscles.
Afferent and efferent connections of the rat tail flick reflex (a model used to analyze pain control mechanisms)
Authors: Grossman M. L. , Basbaum A. I. , Fields H. L. 
Published: January 2005

AbstractAlthough the rat tail flick reflex (TFR) is widely used to study neural mechanisms of analgesia, its underlying anatomy has not been systematically studied. In the present study axonal transport of horseradish peroxidase (HRP) was used to trace the efferent and afferent connections of the TFR. The extensor caudae medialis (ECM), extensor caudae lateralis (ECL), and abductor caudae dorsalis (ACD) were identified as tail flick muscles and injected with HRP. Labeled motor neurons were found in lumbar segments L4–L6, sacral segments S1–S4, and coccygeal segments Co1–Co2; ECL injections also labeled cells in Co3. Motor neurons were concentrated at levels L5‐S2 for ECM, at levels S2‐Co2 for ECL, and at levels L5‐Co1 for ACD.To label the terminals of tail flick afferents, the dorsolateral tail nerve (DLTN) and the ventrolateral tail nerve (VLTN) which innervate the skin of the tail were cut and exposed to HRP. Application of HRP to either DLTN or VLTN labeled afferent terminals in S4, Co1, Co2, and Co3. For DLTN, the greatest density of afferent label was observed in the lateral half of laminae I and II of the dorsal horn. In contrast, labeled afferents from VLTN were concentrated in the medial half of laminae I–II. With longer survival times afferent terminals were also labeled in S3, and in the ventral horn of segments L6‐S2. Bilateral dorsal rhizotomies at levels S3‐Co3 were necessary and sufficient to abolish the tail flick. This corroborated the results from the anatomical studies.Although tail flick motor neurons were present in ten spinal segments, L4‐Co3, tail flick afferents were concentrated caudally in segments S3‐Co3. Thus, in addition to segmental connections, the TFR requires an ascending propriospinal connection from coccygeal and caudal sacral dorsal horn to S1, S2, and to the lumbar enlargement. The intense labeling from tail afferents found in the substantia gelatinosa (SG) is consistent with pharmacological, anatomical, and physiological studies implicating the SG as an important site for inhibition of the tail flick reflex by opiates and by brainstem stimulation.
Two types of GABA‐accumulating neurons in the superficial gray layer of the cat superior colliculus
Authors: Mize R. Ranney , Spencer Robert F. , Sterling Peter 
Published: January 2005

AbstractTwo types of neuron in the upper superficial gray layer of the cat superior colliculus accumulated exogenous 3H‐gamma‐aminobutyric acid intensely. The first type was a horizontal cell with a fusiform cell body, horizontal dendrites, a low synaptic density, but a high percentage of cortical synaptic contacts. This cell had presynaptic dendrites. The second type was a granule cell (type A) with a small round cell body, thin and obliquely oriented dendrites, a moderate synaptic density, and few cortical synaptic contacts. These two types differed in size, shape, dendritic morphology, and patterns of synaptic input. They likely participate in different inhibitory mechanisms.Four types of unlabeled neurons were also identified. Type B granule cells were found only within the upper subdivision of the superficial gray layer. They had moderate‐sized cell bodies, a high synaptic density, and numerous somatic spines. A third type of granule cell (type C) was found only in the deep subdivision of the superficial gray. This type had a low synaptic density and spines that contained synaptic vesicles. Vertical fusiform and stellate forms were also found. We conclude that at least six types of neurons populate the upper superficial gray layer of the cat superior colliculus.
Ultrastructural identification of labeled neurons in the dorsal motor nucleus of the vagus nerve following injections of horseradish peroxidase into the vagus nerve and brainstem
Authors: McLean John H. , Hopkins David A. 
Published: January 2005

AbstractThe efferent connections of two types of neurons in the dorsal motor nucleus of the vagus nerve (DMV) were studied in the cat by light and electron microscopy following horseradish peroxidase (HRP) injections into the cervical vagus nerve or brainstem. After injections of HRP into the vagus nerve, up to 80% of medium‐sized neruons averaging 26 × 20 μm in 1‐μm‐thick sections were retrogradely labeled while no small neurons were labeled in the DMV. Incubation with either diaminobenzidene (DAB) or p‐phenylenediamine‐pyrocatechol (PPD‐PC) chromogens yielded electron‐dense reaction products localized mainly in lysosomes. Identification of label at the ultrastructural level was facilitated by omitting lead citrate staining and by counting numbers of lysosomes, which were higher in labeled neurons. Quantitative comparisons of the dimensions of labeled and unlabeled somata demonstrated that retrograde transport and incorporation of HRP had no effect on cell size within the 2–3‐day survival times used in this study.In order to determine whether neurons in the DMV project to higher levels of the brain stem, large injections of HRP (1–3 μl) were made into the pons, mesencephalon, hypothalamus, and amygdala. After injections of HRP into the brainstem, only small neurons, measuring 17 × 10 μm, were retrogradely labeled. Approximately 90% of the small neurons remained unlabeled following the HRP injections. The ultrastructrual features of the labeled small neurons included an invaginated nucleus, low cytoplasmic/nuclear ratio, and relatively fewer organelles than the medium‐sized neurons. A quantitative analysis of labeled and unlabeled small neurons demonstrated that the labeled neurons were significantly larger than the unlabeled small neurons. Thus, two populations of small neurons may exist in the DMV. One population appears to have ascending projections to higher levels of the brainstem while the other more numerous population may be interneurons or project for only short distances.
The morphology and connections of the posterior hypothalamus in the cynomolgus monkey (Macaca fascicularis). II. Efferent connections
Authors: Veazey R. B. , Amaral D. G. , Cowan W. M. 
Published: January 2005

AbstractThe efferent connections of the posterior hypothalamus have been analyzed autoradiographically in a series of eight cynomolgus monkey (Macaca fascicularis) brains with injections of 3H‐amino acids in different regions of the mamillary complex and the surrounding areas.The medial mamillary nucleus was found to project through the mamillothalamic tract to the ipsilateral anteroventral, anteromedial, and interanteromedial nuclei, and by way of the mamillotegmental tract principally to the deep tegmental nucleus (of Gudden). It also appears to contribute fibers to the medial forebrain bundle, some of which reach as far rostrally as the medial septal nucleus. The lateral mamillary nucleus projects through the mamillothalamic tract bilaterally upon the anterodorsal nuclei of the thalamus, and through the mamillotegmental system to the dorsal tegmental nucleus; it also appears to contribute fibers to the medial forebrain bundle. The supramamillary area has extensive ascending and descending connections that are distributed with the medial forebrain bundle to the hypothalamus and rostral midbrain; in addition, it gives rise to an unusually well‐defined projection to field CA2 of the hippocampus and to a narrow zone overlying the outer part of the granule cell layer and the adjoining part of the molecular layer of the dentate gyrus. We have not been able to distinguish the connections of the posterior hypothalamic nucleus from those of the caudal part of the lateral hypothalamic area: they both appear to contribute substantially to the ascending components of the medial forebrain bundle, and through its descending projection to the tegmental fields of the midbrain, the nucleus centralis superior of the raphe complex, the locus coeruleus, and the central gray as far caudally as the facial nerve. Their further projections to the spinal cord were not examined.Viewed broadly, and in the light of previous work, our observations confirm, once again, the constancy of the connections of the hypothalamus in the mammalian brain, and the pivotal position that the posterior hypothalamus occupies in the elaborate system of connections that links the limbic areas of the forebrain with the complex of structures that Nauta has aptly designated the “midbrain limbic region”.
Amygdalopetal projections in the cat. II. Subcortical afferent connections. A study with retrograde tracing techniques
Authors: Russchen Fokje T. 
Published: January 2005

AbstractThe subcortical afferent connections of the amygdaloid complex of the cat were studied by means of retrograde tracing of horseradish peroxidase and the fluorescent substances bisbenzimid and nuclear yellow. The results of the present study indicate that structures in the basal forebrain, hypothalamus, brainstem, and thalamus project in a topographical manner to the various amygdaloid nuclei.Within the basal forebrain “ventral pallidal” structures project to the lateral and basolateral amygdaloid nuclei. The nucleus of the horizontal limb of the diagonal band and the medial part of the bed nucleus of the stria terminalis project predominantly to the medial and the medial central amygdaloid nuclei. Fibers from the substantia innominata distribute to nearly the entire expanse of the amygdaloid complex.The medial preoptic area and medial hypothalamic nuclei, including the paraventricular, ventromedial, arcuate, premammillary, and supramammillary nuclei, project most heavily to a region of the amygdala which includes the medial and the medial central nuclei. The caudal part of the lateral hypothalamic area sends strong projections to the medial central amygdaloid nucleus and more weakly projects to the basolateral nucleus.Brainstem neurons located in the cell groups A8 and A10, the dorsal raphe nucleus, the locus coeruleus, and the parabrachial nucleus project mainly to the medial central amygdaloid nucleus. Fibers originating in the medial part of the parabrachial nucleus in addition have a dense termination in the anteror amygdaloid area.Of the various midline nuclei of the thalamus which project to the amygdaloid complex, the paraventricular and ventral reuniens nuclei distribute fibers to the medial central and basolateral nuclei. The parataenial and the interventral nuclei project only to the medial central amygdaloid nucleus. Fibers from the interanteromedial nucleus exclusively reach the basolateral nucleus of the amygdala. Caudally in the ventral thalamus the subparafascicular and peripeduncular nuclei have been found to project to the medial, central, lateral, and cortical nuclei. In the posterior thalamus the medial part of the medial geniculate nucleus and the nucleus mediolateralis‐suprageniculate complex give rise to fibers which reach the lateral central amygdaloid nucleus.
The generation and migration of the chick's isthmic complex
Authors: Clarke Peter G. H. 
Published: January 2005

AbstractBy thymidine autoradiography it is shown that the entire isthmic complex is arranged according to a single and very finely grained gradient of proliferation that manifests itself in each of the component cell groups individually. Ventral neurons are generated first, dorsal last. The neurons in the various isthmic cell groups complete their final phase of DNA synthesis mainly between the following stages (of Hamburger and Hamilton, ′51): N. semilunaris, HH‐22 to HH‐24; N. lemnisci lateralis pars ventralis, HH‐23 to HH‐25; N. lemnisci lateralis pars dorsalis, HH‐24 to HH‐27; N. isthmi partes principales magnocellularis and parvocellularis, HH‐24 to HH‐29; N. isthmo‐opticus, HH‐27 to HH‐31. By thymidine autoradiography combined with the peroxidase retrograde transport technique, it is shown that the retinopetal neurons ventral to N. isthmo‐opticus are generated over the same period as the isthmo‐optic neurons and substantially later than the nonretinopetal neurons amongst which they are scattered.Using similar autoradiographic methods but in embryos fixed at various ages, it is then shown that the isthmic alar plate gives rise to all the cell groups of the isthmic complex except possibly N. isthmi pars principalis magnocellularis. In confirmation of Vaage's (′73) account, it is shown that two main migrations, “dorsal” and “dorsolateral”, originate from the dorsal and dorsolateral parts of the germinal epithelium, traveling first laterally and then ventrally, and that some cells from the former subsequently join the latter to create the mixed migration. The dorsal migration gives rise to N. semilunaris, N. isthmi pars principalis parvocellularis and N. isthmo‐opticus, whereas the mixed gives rise to N. lemnisci lateralis partes dorsalis and ventralis and to much of the adjacent reticular formation. The migration is extremely rapid (15–30 μm per hour for the dorsal migration), but much of this speed may be due topassive bulk displacement, since there seems to be little relative movementbetween adjacent cells.
Quantitative analyses of neuronal development in the lateral motor column of mouse spinal cord. III. Generation and settling patterns of large and small neurons
Authors: Holley John A. , Wimer Cynthia C. , Vaughn James E. 
Published: January 2005

AbstractThe generation and settling patterns of large and small lateral motor column (LMC) neurons were compared in the spinal cords of three inbred strains of mice by means of tritiated thymidine autoradiography. No significant strain differences were observed for the number of large LMC cells (presumptive alpha motor neurons) that were heavily labeled on each injection day, although there were significant strain variations for this measure with regard to small LMC neurons (presumed gamma motor neurons and interneurons). The generation of both large and small LMC neurons began at the same time, but peak production of large cells preceded that of the small neurons. There were no strain differences observed for this relationship between the large and small cells. These findings indicate that the LMC, from the time of its initial formation contains cells destined to become large and small neurons. The positions of large and small neurons within the adult LMC relative to their times of origin (settling patterns) were analzyed statistically. A significant ventrodorsal sequence for early‐to‐late generated cells was observed for both large and small LMC neurons. No significant strain difference were found in the analysis of settling patterns. A ventrodorsal settling pattern also has been described for amphibia (Prestige, ′73) and, in conjunction with the proximodistal sequence of limb development describedby other investigators, the ventrodorsal sequence could play a key role in the development of motor neuronal somatotopic organization.
A Golgi study of rat neostriatal neurons: Light microscopic analysis
Authors: Chang H. T. , Wilson C. J. , Kitai S. T. 
Published: January 2005

AbstractAt least two types of large neurons (somatic cross‐sectional areas, SA > 300 μm2) and five types of medium neurons (SA between 100 and 300 μm2) were distinguished in Golgi preparations of the adult rat neostriatum. Type I large cells had aspinous somata with long, radiating, sparsely spined dendrites which were sometimes varicose distally, whereas type II large cells had spines on both somatic and dendritic surfaces. Type I medium cells had aspinous somata and proximal dendrites, but their distal dendrites were densely covered with spines. Type II medium cells had somatic spines, and their radiating dendrites were sparsely spined. Other medium cells had no somatic spines: Type III cells had poorly branched and sparsely spined dendrites. Type IV cells had profusely branched, sparsely spined dendrites. Type V cells had radiating and varicose dendrites which could also be sparsely spined.Several small neurons (SA mostly less than 100 μm2) were also found in the rat neostriatum: Some had aspinous soma with sparsely spined dendrites; others had somatic spines.Except for the type II large cells, intrinsic axon collaterals were observed for every type of neuron, indicating that they all had local integrating functions.
Subcortical structures projecting to visual cortical areas in squirrel monkey
Authors: Tigges Johannes , Tigges M. , Cross N. A. , McBride R. L. , Letbetter W. D. , Anschel S. 
Published: January 2005

AbstractIn 17 adult squirrel monkeys (Saimiri), horseradish peroxidase was used as a retrograde tracer substance to reveal the subcortical structures (other than the lateral geniculate nucleus and pulvinar) which project to the occipital lobe, and, in particular, to the central visual field representation in areas 17, 18, 19, and MT. Evidence is provided that each of areas 17, 18, and MT receives a projection from locus coeruleus, nucleus dorsalis raphae, nucleus annularis, nucleus centralis superior, formatio reticularis pontis oralis, nucleus basalis of Meynert, lateral hypothalamus, claustrum, and nuclei paracentralis and centralis medialis thalami. Area 19 receives a projection from all these structures except from the nucleus annularis. Only area MT was determined to be a target of a projection from the nucleus linearis. For technical reasons, only area MT was determined to receive afferent fibers from the nucleus basalis lateralis amygdalae. The results indicate that there is no topographical organization of subcortical inputs to the central visual field representation in individual cortical areas.
Structure of the synaptic membranes in the inner plexiform layer of the retina: A freeze‐fracture study in monkeys and rabbits
Authors: Raviola Elio , Raviola Giuseppina 
Published: January 2005

AbstractThe internal structure of the synaptic membranes in the inner plexiform layer (IPL) of the retina of monkeys and rabbits was studied with the freeze‐fracturing technique. In ribbon synapses, the presynaptic active zone is characterized by an aggregate of P‐face particles, images of synaptic vesicle exocytosis, and forming coated vesicles which occupy distinct, contiguous membrane domains from apex to base of the synaptic ridge. The postsynaptic membrane contains a prominent aggregate of homogeneous particles which remain associated with the E‐face. In the presynaptic membrane of conventional synapses, images of synaptic vesicle exocytosis are intermingled with large P‐face particles, whereas forming coated vesicles surround the active zone. Three types of internal organization characterize the postsynaptic membrane of conventional synapses. Usually, the postsynaptic membrane exhibits the same internal structure as the surrounding nonjunctional plasmalemma. A second, less common type of conventional synapse contains a loose aggregate of heterogeneous particles which remain associated with the P‐face. Finally, synapses were exceptionally found which are macular in shape and contain an aggregate of E‐face particles within the postsynaptic membrane. The freeze‐fracture evidence suggests that the axonal endings of bipolar cells—or at least some of them—make excitatory synapses, whereas the vast majority of amacrine cell dendrites make inhibitory synapses. Additional specializations of the cell surface in the IPL include gap junctions, puncta adhaerentia, subsurface cisterns, and cell corner aggregates.
The distribution of axon collaterals from the olfactory bulb and the nucleus of the horizontal limb of the diagonal band to the olfactory cortex, demonstrated by double retrograde labeling techniques
Authors: Luskin Marla B. , Price Joseph L. 
Published: January 2005

AbstractThree different pairs of double retrograde axonal tracers have been used to study the distribution of axon collaterals from individual cells in the olfactory bulb and the nucleus of the horizontal limb of the diagonal band: (1) horseradish peroxidase (HRP) and tritiated apo‐HRP (3H‐HRP), (2) HRP and 125I‐wheat germ agglutinin (I‐WGA), and (3) the flurochromes true blue (TB) and bisbenzimide (BB) or nuclear yellow (NY). With each combination of tracers, paired injections were made into different parts of the olfactory system, and the olfactory bulb and the nucleus of the diagonal band were examined for the presence and arrangement of cells labeled with one or both retrograde tracers.In the olfactory bulb both single and double retrogradely labeled mitral cells were found following injections in disparate parts of the olfactory cortex. Furthermore, no consistent pattern was found in the distribution of single‐ or double‐labeled cells in the olfactory bulb; that is, the distribution of cells labeled from one area of the cortex was not consistently different from the distribution of cells labeled from other parts of the cortex. Therefore, it was concluded that individual mitral cells project to widely spaced parts of the olfactory cortex, and that there is no apparent correspondence between the location of a given cell in the olfactory bulb and the distribution of its axon in the cortex.In contrast to this, cells in the nucleus of the horizontal limb of the diagonal band were only rarely double‐labeled from nonoverlapping injections into the olfactory cortex or olfactory bulb, although overlapping injections produced a high proportion of double‐labeled cells. Cells which were single‐labeled from different injection sites were extensively intermixed within the nucleus. Therefore, in this case it was concluded that individual cells project to relatively restricted areas, although there was again no apparent correspondence between the position of a cell in the nucleus and the terminal field of its axon.