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PubMed1991

[Pre-project evaluation of a government based international family planning co-operative project--from a survey at project site in Colombia].

A government based international co-operative project for family planning was formulated between Japan and Colombia. A baseline survey was carried out at the project site in northern Colombia as a pre-project evaluation. A total of 330 households were sampled and the housewives were interviewed concerning family planning. Births averted by the existing government program were estimated employing Bongaarts prevalence model. In addition, background and conditions leading to inability to receive family planning services were analyzed. The results showed that of total births averted, government programs contributed around 50% reflecting the apparent insufficiency of the services in reaching women in their forties and teens. Educational attainment and place of birth on the part of the woman, household income, discussion of number of children desired between husband and wife were among the most important factors for women wishing contraception practice but not being able to receive family planning services. Based on this analysis, a service program was mapped out to meet the need of residents of the project site.

Adolescent↗

PubMed1989

Brainstem projecting neurons in the rat basal forebrain: neurochemical, topographical, and physiological distinctions from cortically projecting cholinergic neurons.

Magnocellular regions of the basal forebrain contain cholinergic neurons that project to the cerebral cortex. Neurons in the same basal forebrain regions innervate the brainstem. The present study investigated whether these brainstem projecting neurons are cholinergic, project also to the cortex, and share similar physiological properties as cortically projecting neurons. Data with retrograde tracing from various regions of the pons, medulla, and cortex combined with choline acetyltransferase immunofluorescence indicated that: 1) brainstem projecting neurons are usually segregated from cortically projecting and/or cholinergic neurons in the basal forebrain, 2) virtually no brainstem projecting neurons in the basal forebrain are cholinergic, and 3) only rarely do basal forebrain neurons have axon collaterals that project to both cortex and brainstem. Extracellular recordings from basal forebrain neurons confirmed the paucity of axonal collateralization and the topographic segregation between cortically and brainstem projecting basal forebrain neurons, and, in addition, showed that brainstem projecting neurons have a slower mean conduction velocity than cortically projecting neurons. These observations suggest that basal forebrain neurons projecting to the brainstem (pons, medulla) and the cortex represent separate cell populations in terms of projections, neurotransmitter content, distribution, and physiological properties.

Action Potentials↗

PubMed1976

[A standard projection for temporomandibular joint radiographs in oblique lateral projection].

A standard projection for temporomandibular joint radiographs in oblique lateral transcranial projection was determined by a clinical method. The individualized projections from 1644 TMJ radiographs, made with a fluoroscopic examination unit with image intensifier, were evaluated in a pilot study. A mean projection 20 degree cranial eccentric and 12 degree dorsal eccentric resulted. Reference planes were the Camper plane and the middle frontal plane. This projection, corrected in 22 degree/10 degree, was studied in a clinical study in order to test the readability of the radiographs of 100 temporomandibular joints. The readability of these radiographs was compared with that of radiographs obtained with an individualized projection. 81 radiographs out of 100 were well or very well readable, 7 were limitedly readable and 12 were unreadable. The number of radiographs in these last two categories could not be reduced by an individual angulation of the x-ray beam. Therefore anatomical reasons have to be considered to be responsible for the insufficient readability of these TMJ radiographs. This projection avoided superposition of the petrous portion of the temporal bone without giving an extreme view of the lateral slope of the condyle. From the evaluation of the 100 individualized projections resulted a mean projection 21 degree/10 degrees, which confirmed the projection 22 degrees/10 degrees used in this study. The projection 21-22 degrees/10 degrees turned out to be a most favourable projection for the dental office to make TMJ radiographs in connection with the diagnosis of the occlusion in patients with TMJ disorders.

Adolescent↗

PubMed1976

The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. III. The projection to the vermal visual area.

Horseradish peroxidase (HRP) was injected separately in one of the cerebellar lobules VI, VIIA, VIIB, VIIIA or VIIIB (together corresponding to the vermal visual area) in 17 cats. After 1-3 days the distribution of labeled cells in the inferior olive was mapped. In spite of some overlapping it is clear that the various lobules of the vermal visual area receive fibers from separate parts of a horseshoeshaped region in the caudal half of the contralateral medial accessory olive (fig. 5C). The projection area of lobule VIIA is found caudomedially and overlapping with the area supplying lobule VIIB. This in addition receives a few fibers from the nucleus beta. Fibers terminating in lobule VIIIA arise caudolaterally as do fibers destined for lobule VIIIB. A central part of the total projection area projects to lobule VI. Following injections leading to a similar extent of cortical staining in lobules VI, VII or VIII the projection of labeled cells in the corresponding projection areas differ markedly. In the area of lobule VII apparently all cells are labeled, in the area of lobule VI the density of labeled cells is considerably less, and in that of lobule VIII there are rather few labeled cells. In a few cases with widespread staining of the cerebellar visual area there was spreading of HRP to the nucleus fastigii. The projection to this form the olive was therefore investigated to avoid erroneous conclusions. In the discussion it is pointed out that on most points our findings agree fairly well with the results of studies of the olivocerebellar projection undertaken with other methods (studies of retrograde cellular changes, electrophysiological methods). No support for a longitudinal subdivision of lobules VI-VIII was found. Studies of the available literature indicate that the areas in the medial accessory olive projecting onto lobules VI-VIII probably do not receive direct afferents from regions which are known to be concerned in the transmission of visually evoked impulses. Fibers to the olive from the superior colliculus appear to pass to the nucleus beta only. This projects mainly to the uvula, to a little extent only to lobule VII. However, it may be imagined that visual impulses may reach the vermal visual area via the inferior olive by way of intercalated neurons, for example in the mesencephalic RF. Major contingents of afferents to the olivary regions projecting onto the vermal area come from the spinal cord, the motor cortex and the periaqueductal gray.

Animals↗

PubMed1986

Origin of mammalian thalamocortical projections. I. Telencephalic projections of the medial geniculate body in the opossum (Didelphis virginiana).

Telencephalic projections from the medial geniculate nucleus (MG) in opossum were traced with tritiated leucine autoradiography and by horseradish peroxidase and fluorescent dye retrograde labeling techniques. The results show that the opossum's MG contains two separate populations of neurons-one in the anterior two-thirds of MG projecting to auditory neocortex, the other occupying the entire caudal one-third of MG and projecting mostly to lateral amygdala and putamen. Because the subcortical projection of the MG in opossum is larger than that seen in any other mammal to date, it is reminiscent of the subcortical projections of the MG in reptiles and birds. Furthermore, when the subcortical projections of the MG in reptiles and opossums are compared with similar subcortical projections of the MG in rats, cats, and monkeys, the proportion of the MG neurons projecting to subcortical structures is seen to be inversely related to the recency of each animal's common ancestry with primates. The possibility that the subcortical projection of the MG in mammals is homologous with that seen in reptiles or birds implies that it might be a dwindling vestige of the projection present in the common ancestry of reptiles and mammals.

Animals↗

PubMed1977

The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. IV. The projection to the anterior lobe.

Following injections of horseradish peroxidase (HRP) in the cerebellar cortex of the anterior lobe of the cat, the distribution of labeled cells in the inferior olive was mapped. The findings largely confirm those made previously in studies of olivary retrograde cell loss following cerebellar ablations (Brodal, '40b). In addition, they reveal further olivary areas projecting onto the anterior lobe, and permit a more detailed analysis of the pattern in this projection. Concerning major points the results are in agreement with physiological studies by Armstrong et al. ('74). They bring supporting evidence for a longitudinal zonal pattern in the anterior lobe (fig. 6C). The middle zone of the vermis receives its fibers from a large central area in the caudal half of the medial accessory olive, a lateral zone of the vermis from the lateral half of the dorsal accessory olive. Both olivary areas project to the corresponding cerebellar zone throughout lobules V-I. The lateralmost part of the anterior lobe (lobules IV-V) receives afferents from an area in the dorsal lamella of the principal olive. The intermediate part of lobules IV-V receives afferents from the medial half of the dorsal accessory olive and from an area in the rostral half of the medial accessory olive. There is suggestive evidence that the latter projects to a middle zone, the former to a medial and a lateral zone within the intermediate part as found physiologically. Conclusions concerning projections to the intermediate part of lobules III-II could not be made. The findings in this and preceding studies with the HRP-method show that the concept of a longitudinal pattern in the cerebellum is scarcely generally valid of the entire olivocerebellar projection. Within the projections of the lateral half of the dorsal accessory olive and the area in the rostral part of the medial accessory olive there appears to be a topical relation with the folial pattern in the anterior lobe. An analysis of the findings with reference to the afferents traced anatomically to the various olivary areas permits some conclusions as to the functional role of the olivary areas. Comparison with Oscarsson's ('73) diagram of the sites of termination of two of the spinal-olivary pathways (his DF-SOCP) and VF-SOCP) permits an anatomical explanation as concerns the projections to the vermis, while correlations as concerns the intermediate part are less satisfactory.

Animals↗

PubMed1977

The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. VI. The projection onto longitudinal zones of the paramedian lobule.

Microinjections (30-50 nl) of a horseradish peroxidase (HRP) suspension of 25% (wt./vol.) were made in different folia of the paramedian lobule of cats, and the sites of occurrence of labeled cells in the inferior olive were precisely determined. In each case only a small number of cells are labeled, aggregated in a minute area. The labeled cells are found within three only of the four olivary areas previously determined (Brodal et al., '75) to project onto the paramedian lobule (fig. 1): one area in the rostral half of the medial accessory olive, another in the dorsal accessory olive (except its caudalmost part), and a third in part of the caudal half of the dorsal lamella of the principal olive. Labeled cells were never found in the fourth area, the ventral lamella. A distinct zonal pattern in the projection is demonstrated (figs. 3, 5B): a middle longitudinal zone of the paramedian lobule receives olivary afferents from the area in the medial accessory olive, a medial zone from part of the projection area in the dorsal accessory olive, a lateral zone from part of the projection area in the dorsal lamella. This zonal projection appears to extend throughout the length of the paramedian lobule (the two caudalmost folia could not be studied). tthe somatotopical pattern in the projections from the accessory olives described previously (Brodal et al., '75) is confirmed. The pattern of a zonal projection obtained with the HRP-method (fig 5B) is simpler than that deduced by Armstrong et al ('74) from recordings of antidromic potentials in the olive (fig 5A). Concerning main points there is satisfactory agreement. The phenomenon that following microinjections of HRP in superficial parts of the folia labeled cells occur within parts only of the regions of the olive which contain labeled cells following large HRP-injections in the paramedian lobule is discussed.

Afferent Pathways↗

PubMed1978

The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. VII. The projection to lobulus simplex, crus I and II.

The olivocerebellar projection to lobulus simplex, crus I and II in the cat was investigated by means of retrograde axonal transport of horseradish peroxidase (HRP). The distribution of labeled cells in the inferior olive following HRP injections in lobulus simplex, crus I and II confirmed the findings by Brodal ('40b) that the rostral half of the principal olive projects to these areas of the cerebellar hemisphere. However, concerning details there are some differences in so far as the heaviest contribution to crus I comes from the medial parts of the ventral and dorsal lamella, that to crus II from its lateral part, especially the ventral bend. The present findings show that in addition the rostral part of the medial and the rostromedial part of the dorsal accessory olive project to these areas of the cerebellar cortex. Further details in the projection are shown in figure 8B. The findings agree fairly well with the electrophysiological results of Armstrong et al. ('74) and the experimental anatomical data of Groenewegen and Voogd ('77a,b). An attempt is made to correlate the findings with the pattern of longitudinal zonal subdivision of the cerebellum. There is evidence for a topical organization within the projection to crus I and II and parts of their projection areas in the principal olive. The distribution of the labeled cells which project to lobulus simplex, crus I and II is discussed in relation to afferent pathways to the inferior olive.

Animals↗

PubMed1978

An investigation of the cerebellar cortico-nuclear projections in the rat using an autoradiographic tracing method. I. Projections from the vermis.

The topography of the projections from the vermis of the cerebellar cortex to the intracerebellar nuclei (excluding the vestibular complex) was newly investigated in the rat using an autoradiographic technique. The projection were strictly ipsilateral and the majority terminated in nucleus fastigus although there were small projections to the medial pole of nucleus interpositus. The only portion of fastigius which was never heavily labelled was the dorsolateral protuberance. Some rostrocaudal localisation was evident with lobules II-V projecting to rostral fastigius (Fm), lobules VI-VIII projecting mainly more caudally (Fcm and Fm) and lobule IX projecting to the caudoventral tip of fastigius. Nevertheless, even the densest portions of the terminal fields often overlapped heavily, suggesting that, in the rat, in contrast to some other species, the rostrocaudal localisation is such that individual lobules do not possess private termination fields of any extent. Such an arrangement should provide ample opportunity for integration by individual nuclear neurones of input from extensive areas of cortex. In the mediolateral plane, localisation was more evident, with the medial vermis projecting to the medial pole of fastigius and the lateral portion to lateral fastigus and less heavily to medial interpositus.

Animals↗

PubMed1990

Quantitative re-evaluation of descending serotonergic and non-serotonergic projections from the medulla of the rodent: evidence for extensive co-existence of serotonin and peptides in the same spinally projecting neurons, but not from the nucleus raphe magnus.

A quantitative analysis of serotonin (5-HT) and spinally-projecting neurons was re-evaluated in the rodent. The findings indicate that most (nearly 90%) of the medullary 5-HT neurons projected to the lumbar spinal cord, and most (up to 85%) of the spinally projecting neurons within the distribution of the serotonergic neurons contained 5-HT immunoreactivity. However, in nucleus raphe magnus (NRM) only about two-thirds of the projection cells were 5-HT immunoreactive. These data support two general conclusions: (1) the raphe-spinal system consists primarily of an extensive 5-HT pathway with neuronal subsets containing the co-localized peptides. Only the NRM contains a major non-5-HT projection. (2) As most of the medullary 5-HT neurons project to the caudal spinal segments of the rodent, collateralization of individual 5-HT neurons is extensive and widespread, existing to different spinal cord levels, as well as to other medullary nuclei, e.g., cranial nerve and inferior olivary nuclei. These findings argue that although differences are present within the 5-HT distributions, the raphe-spinal system as a whole should be considered to be a relatively homogeneous pathway containing 5-HT as the common element rather than as separate populations containing major projections of 5-HT alone, 5-HT co-localized with peptides and peptides without 5-HT.

Animals↗

PubMed1989

[Afferent projections to the uvula in the cat. I. Climbing fiber projections].

The inferior olive afferents to the cerebellar uvula were studied by means of retrograde axonal transport of horseradish peroxidase (HRP) in the cat. Following large and small injections of HRP into the uvula, the distributions of labeled cells in the inferior olive were investigated. As to the climbing fiber projection, it is revealed that there are six longitudinal parasagittal zone extending throughout the dorsal and ventral uvula. That is, the caudal aspect of the nucleus beta projects to a most medially oriented zone (caudal beta zone), the rostral aspect of the nucleus beta projects to a zone (rostral beta zone) oriented lateral to the caudal beta zone, the caudal aspect of the medial accessory olive (MAO) projects to a zone oriented lateral to the rostral beta zone, the dorsomedial cell column projects to a zone (dorsomedial cell column zone) oriented in the intermediate part of the uvula, the ventral lamella of the principal olive (vlPO) projects to a more lateral zone (vlPO zone), and the rostral aspect of the MAO projects to the most lateral zone (rostral MAO zone).

Afferent Pathways↗

PubMed1975

On the absence of a rubrothalamic projection in the monkey with observations on some ascending mesencephalic projections.

In order to determine whether there is a rubrothalamic projection in the rhesus monkey, the ascending degeneration resulting from electrolytic lesions made in the red nucleus and adjacent mesencephalon in animals surviving at least one year after bilateral interruption of the superior cerebellar peduncles (PCS) was studied by means of the Fink-Heimer technique. In a necessary preliminary step it was shown that virtually all of the degeneration disappeared from the thalamus within twelve months after PCS interruption so that degeneration resulting from the subsequent electrolytic mesencephalic lesions could be attributed to interruption of non-cerebellar ascending fibres. The results show that degeneration was present in the thalamus following the electrolyte mesencephalic-diencephalic lesions but it could be accounted for on the basis of damage either to residual PCS fibres, to somatosensory pathways, to intrathalamic connections or to cell groups or projection fibres of the reticular formation, substantia nigra or globus pallidus. It is concluded that there is no direct rubrothalamic projection in the monkey and, in particular, no evidence of a projection from the red nucleus to the ventral lateral or ventral anterior thalamic nuclei. The results also indicate that the mesencephalic reticular formation is the main source of ascending afferents to the nucelus reticularis thalami. Some observations were made concerning nigrostriatal and nigrothalamic projections. Retrograde cell changes resulting from unilateral lesions made caudal to the red nucleus were studied in three animals. The observed cell changes are interpreted as being consistent with the conclusion that there is no rubrothalamic projection.

Age Factors↗

PubMed1990

Visual projections induced into the auditory pathway of ferrets. I. Novel inputs to primary auditory cortex (AI) from the LP/pulvinar complex and the topography of the MGN-AI projection.

The organization of cortical circuitry responsible for processing sensory information is a subject of intense examination. However, it is not known whether cortical cells in different sensory cortices process information in a way that is specific to the modality of their input, or whether there are commonalities in processing circuitry across different cortices. In our laboratory, this question has been investigated at the level of the geniculocortical pathway by routing information of one sensory modality into the processing circuitry of another modality. Appropriate early lesions cause growth of retinal axons into the auditory thalamus (MGN) (Sur et al., Science 242:1437, '88). Previously, we have established that the MGN carries the resulting visual information on to primary auditory cortex (AI), which thus contains visually responsive neurons and a topographic representation of the retina (Roe et al., Soc. Neurosci. Abstr. 14:460, '88; Sur et al., Science 242:1437, '88). In this paper, we describe anomalous projections from the dorsal part of the thalamus, specifically the lateral posterior/pulvinar complex, into AI. This result demonstrates that thalamic neurons belonging to one modality can be induced to project to cortex that is normally of a different modality. In addition, we have studied in detail the nature of the MGN to AI projection in these animals as compared to the normal projection. The MGN to AI projection appears to be unaltered by the lesions; the location and topography of labelled cells are similar to that in normal animals. Because the MGN to AI projection is still highly divergent along the "isofrequency" dimension when compared to the tonotopic dimension, our data suggest that visual topography in the cortical map is created within the auditory cortex, perhaps by activity-dependent sharpening of the retinal representation during development.

Animals↗

PubMed1990

Quantitative study of the tectally projecting retinal ganglion cells in the adult frog: I. The size of the contralateral and ipsilateral projections.

The proportion of ganglion cells connected to the several central targets of the retinal projection varies in different species. In the frog, the retinotectal projection is clearly the largest branch of the optic pathway and the relative size of the tectally projecting population can be expected to be correspondingly great. However, there have been no studies aimed at quantifying the size of this population and at partitioning its contralateral and ipsilateral components. We injected the tectum with horseradish peroxidase (HRP) dried onto fine needles to count the numbers of retinal ganglion cells labeled by retrograde transport. The retinas were prepared as flat-mounts to facilitate the cell counting. The tecta were injected either unilaterally or bilaterally in mirror-symmetric loci. Specimens included completely normal frogs and frogs which had undergone unilateral optic nerve regeneration, although only normal retinas are presented in the current study. The retrograde transport interval was varied progressively (from 3 to 5 days), and single or multiple injections of HRP were placed singly or as clusters, in order to increment the cell counts toward a level of saturation. Approximately 70.9% of the neurons in the ganglion cell layer could be labeled by this method. Correcting for the presence of displaced amacrine cells, estimated to comprise approximately 16% of the neurons in the ganglion cell layer (Scalia et al., '85, Brain Res. 344:267-280), we calculate that approximately 84.4% of the retinal ganglion cells project contralaterally to the optic tectum. Flat-mounted retinas ipsilateral to unilaterally injected tecta of completely normal frogs were also examined for labeled cells. The results of injections in the rostrolateral, caudomedial, and caudolateral tectum were studied. We found that ipsilaterally labeled cells comprised no more than 2.3% of the overall population of ganglion cells in the ganglion cell layer. The ipsilaterally projecting cells were found in loci which were approximately mirror-symmetric to the regions of maximal cell labeling in the contralateral retinas from the same animals. The ipsilateral population was always displaced toward the periphery of the retina with respect to the contralateral population, regardless of whether the contralateral locus was centered in the temporal, ventronasal, or dorsonasal sector of the retina. Because the ipsilaterally projecting ganglion cells form such a minor population, and because they exist in the monocular as well as the binocular parts of the retina, it seems likely that they may not play a significant role in visual function in the frog.

Afferent Pathways↗

PubMed1991

Organization of ascending hypothalamic projections to the rostral forebrain with special reference to the innervation of cholinergic projection neurons.

Axonal projections from hypothalamic nuclei to the basal forebrain, and their relation to cholinergic projection neurons in particular, were studied in the rat by using the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L) in combination with choline acetyltransferase (ChAT) immunocytochemistry. Discrete iontophoretic PHA-L injections were delivered to different portions of the caudal lateral hypothalamus, as well as to various medial hypothalamic areas, including the ventromedial, dorsomedial, and paraventricular nuclei, and anterior hypothalamic and medial preoptic areas. The simultaneous detection of PHA-L-labeled fibers/terminals and ChAT-positive neurons was performed by using nickel-enhanced diaminobenzidine (DAB) and nonenhanced DAB as chromogens. Selected cases were investigated at the electron microscopic level. Ascending hypothalamic projections maintained an orderly lateromedial arrangement within the different components of the medial forebrain bundle, as well as with respect to their terminal projection fields (e.g., within the bed nucleus of the stria terminalis and lateral septal nucleus). The distribution pattern of hypothalamic inputs to cholinergic projection neurons corresponded to the topography of ascending hypothalamic axons. Axons originating from neurons in the far-lateral hypothalamus reached cholinergic neurons in a zone that extended from the dorsal part of the sublenticular substantia innominata (SI) caudolaterally, to the lateral portion of the bed nucleus of the stria terminalis rostromedially, encompassing a narrow band along the ventral part of the globus pallidus and medial portion of the internal capsule. Axons originating from cells in the medial portion of the lateral hypothalamus reached cholinergic cells primarily in more medial and ventral parts of the SI, and in the magnocellular preoptic nucleus and horizontal limb of the diagonal band nucleus (HDB). Axons from medial hypothalamic cells appeared to contact cholinergic neurons primarily in the medial part of the HDB, and in the medial septum/vertical limb of the diagonal band complex. Electron microscopic double-labeling experiments confirmed contacts between labeled terminals and cholinergic cells in the HDB and SI. Individual hypothalamic axons established synapses with both cholinergic and noncholinergic neuronal elements in the same regions. These findings have important implications for our understanding of the organization of afferents to the basal forebrain cholinergic projection system.

Afferent Pathways↗

PubMed1988

Topographic projections from the basal ganglia to the nucleus tegmenti pedunculopontinus pars compacta of the cat with special reference to pallidal projection.

Projections from the basal ganglia to the nucleus tegmenti pedunculopontinus pars compacta (TPC) were studied by using anterograde and retrograde tracing techniques with horseradish peroxidase conjugated with wheat germ agglutinin (WGA-HRP) in the cat. Following WGA-HRP injections into the medial TPC area, a substantial number of retrogradely labeled cells were seen in the entopeduncular nucleus (EP) and medial half of the substantia nigra pars reticulata (SNr), whereas following WGA-HRP injections into the lateral TPC area, labeled cells were marked in the caudal half of the globus pallidus (GP) and lateral half of the SNr. To confirm the retrograde tracing study, WGA-HRP was injected into the EP or the caudal GP, and anterograde labeling was observed in the TPC areas. Terminal labeling was located in the medial TPC area in the EP injection case, while terminal labeling was observed in the lateral TPC area in the caudal GP injection case. Projections from the striatum to the pallidal complex (the EP and the caudal GP) were also studied autoradiographically by injecting amino acids into various parts of the caudate nucleus and the putamen. Terminal labeling was distributed over the whole extent of the EP and the rostral GP following injections into the rostral striatum (the head of the caudate nucleus or the rostral part of the putamen), while terminal labeling was distributed over the caudal GP following injections into the caudal striatum (the body of the caudate nucleus or the caudal part of the putamen). From these findings, we conclude that there exists a medio-lateral topography in the projection from the basal ganglia to the TPC: The EP receives afferent projections from the rostral striatum and projects to the medial TPC area, whereas the caudal GP receives projections from the caudal striatum and sends fibers to the lateral TPC area.

Animals↗

PubMed1979

Spinal projections from the lower brain stem in the cat as demonstrated by the horseradish peroxidase technique. II. Projections from the dorsolateral pontine tegmentum and raphe nuclei.

The descending projections to the spinal cord arising from the dorsolateral pontine tegmentum and brain stem raphe nuclei have been investigated by means of the horseradish peroxidase (HRP) technique. Particular attention was taken to clarify the cells of origin and the funicular trajectory of these spinal projections. After injections of HRP into the spinal cord, a significant of HRP labeled neurons were observed in the following dorsolateral pontine tegmental structures: (1) an area ventral to the nucleus cuneiformis; (2) principal locus coeruleus; (3) locus coeruleus a; (4) locuse subcoeruleus; (5) Kölliker-Fuse nucleus; and (6) nucleus parabrachialis lateralis. As a rule, the projections are ipsilateral and descendaphe-spinal projections, we have demonstrated that the nucleus raphe dorsalis also sends axons to the cervical segment of the spinal cord. Furthermore, in accord with previous reports, HRP labeled cells were also identified in the nucleus raphe magnus, pallidus and obscurus, but not in the nucleus raphe centralis superior and pontis. On the whole the present study further clarified the organization of spinal projections from the dorsolateral pons and raphe nuclei and provided some additional anatomical data for the physiology of the tegmentospinal and raphe-spinal projections.

Animals↗

PubMed1991

Neurogenesis of ascending supraspinal projection neurons: ipsi- versus contralateral projections.

The present study tests the hypothesis that contralaterally projecting supraspinal projection neurons (SPNs) are generated prior to ipsilaterally projecting SPNs. Neuronal time of origin was determined by injecting pregnant rats with tritiated thymidine on one of embryonic (E) days E12 through E15. In mature offspring of thymidine-treated dams, SPNs in the lumbar cord were retrogradely labelled with True Blue delivered at the site of a hemisection in spinal segment C3. Ipsi and contralaterally projecting SPNs in laminae I, VII and VIII and the lateral spinal nucleus, which are known to give rise to long sensory pathways, were generated simultaneously throughout their neurogenic period (E12-E14), while ipsilaterally projecting SPNs in lamina IV and the nucleus dorsalis, which give rise to short sensory pathways, completed neurogenesis one day later (E15). Results suggest that the projection target and its distance from the nerve cell body of origin are more consistent correlates of the duration of the neurogenic period than the course of the axon.

Animals↗