摘要:

AbstractThe projection of cortical areas 17, 18, and 19 onto the laminar part of the dorsal lateral geniculate nucleus was investigated with degeneration methods and with the autoradiographic axon tracing method. In agreement with previous accounts, degenerating cortical axons stained by the Nauta method were restricted to laminae A, A1, C and to the interlaminar zones. In contrast, adjacent sections stained with the Fink‐Heimer method showed fine dust like degeneration throughout all of the laminae of the nucleus. Comparisons of Fink‐Heimer degeneration resulting from lesions of area 17 with that resulting from lesions of areas 18 and 19 further suggested that the area 17 projection is heavier and more uniform than the projections from areas 18 and 19.Autoradiographic tracing of axons after intracortical injections of3H‐proline provided detailed demonstrations of the cortical projection patterns that confirmed the Fink‐Heimer results. Following restricted injections of areas 17 or 18 the termination zones in the dorsal lateral geniculate nucleus consisted of columns of labeled tissue oriented perpendicular to the laminae of the nucleus. Area 17 was found to project heavily and uniformly throughout all of the laminae of the nucleus. The projection from area 18 also extended throughout all of the laminae of the nucleus, but was sparser and less uniformly distributed than that from area 17. Projections from area 18 distributed more heavily to the interlaminar zones and to lamina C than to laminae A, A1, C1, C2, or C3. A projection from area 19 to laminae C1, C2, and C3was also demonstrated autoradiograp

ISSN:0092-7317    

DOI:10.1002/cne.901630402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractThe goals of this study were: (1) to describe the total pattern of projections from the optic tectum ofIguana iguanaandPseudemys scripta; and (2) to describe the contributions of particular lamina of the Iguana's optic tectum to this total pattern. Lesions were made in the optic tectum of the Iguana which damaged either all or only certain tectal laminae and, for comparison with the Iguana, lesions in the turtle's optic tectum were made which involved all laminae. The anterograde degeneration resulting from these lesions was stained with the Fink‐Heimer ('67) method. The total pattern of projections from the optic tectum in the Iguana and the turtle is similar to that reported for representatives of other vertebrate classes. That is, the optic tectum gives rise to ipsilateral ascending projections to pretectal nuclei, to nucleus rotundus and to nucleus geniculatus lateralis pars ventralis of the diencephalon and, in addition, to a contralateral ascending pathway which courses via the supraoptic decussation to the contralateral diencephalon. Tectotectal connections and several descending pathways were also recognized in each species. The descending pathways include ipsilateral tectobulbar and tecto‐isthmi pathways and a contralateral predorsal bundle.Lesions which damaged only certain tectal laminae in the Iguana revealed a laminar organization of the efferent projections. A lesions restricted to the superficial retinal‐recipient layers, stratum griscum et album superficiale, resulted in degeneration in only nucleus isthmi pars magnocellularis and nucleus geniculatus lateralis pars ventralis. A lesion which involved both the retinal‐recipient layers and stratum griseum centrale resulted in degeneration in only one additional structure, nucleus rotundus. A small lesion involving the deep periventricular layer as well as the superficial layers produced degeneration in the predorsal bundle and the ipsilateral tectobulbar tract as well as in the structures receiving input from the more superficial layers. These results are compared to the results of similar analyses of the superior colliculus in

ISSN:0092-7317    

DOI:10.1002/cne.901630403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractThe ontogeny of the spatial organization of some components of the molecular layer was investigated in cerebella sectioned systematically in the sagittal, coronal and horizontal planes.There is no discernible organization in the distribution of cells of the proliferative zone of the external germinal layer (EGL) but from birth the differentiating bipolar cells of the subproliferative zone are aligned parallel to the surface and to the long axis of the folium. While they are still in or at the base of the EGL, the bipolar cells emit long processes, the future parallel fibers. The next step is the outgrowth of a vertical process which may reach the base of the molecular layer before the granule cell nucleus becomes translocated. The idea that the cell body truly migrates through the molecular layer is not supported by the observations.Bergmann glia cells are frequently seen in Golgi material in neonates but they are probably less numerous than in older infants and their processes are not as well as aligned. It is only gradually that the EGL is perforated by glial endfeet which in older infants are occasionally organized into longitudinal rows. In mature cerebella the parallel fibers are separated by thin and relatively narrow, unstained spaces which are oriented in the longitudinal plane and can be traced from the pial surface to a zone just above the layer of Purkinje cells. It is postulated that these spaces are occupied by glial palisades formed by apposed thin vertical processes to which many Bergmann glia cells contribute. The alignment of these palisades is dependent on the orientation of parallel fibers. When the parallel fibers are reoriented by X‐irradiation the glial palisades become correspondingly realigned.These observations indicate that the orieted growth of parallel fibers, which follows the polarization of bipolar cells, determines the spatial organization of the glial framework of the molecular layer. They also suggest that the glial palisades mediate functions that are not primarily developmental in natur

ISSN:0092-7317    

DOI:10.1002/cne.901630404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractThe spinal grey projects upon the contralateral superior colliculus via two overlapping pathways in the lateral funiculus. One, more ventrally placed, is the classical spinotectal tract, which crosses immediately in the spinal cord and remains crossed. The other, lying more dorsally, ascends homolaterally but is subject to delayed crossing in the brainstem (especially the intertectal) commissures to reach the contralateral colliculus. Both sets of fibers end only in the caudal half of the colliculus, predominantly in the stratum album intermedium. The projections from individual cord segments distribute in an ordered fashion as a series of transverse, overlapping bands, the cervical cord projecting most rostrally, the sacro‐coccygeal most caudally. Additional fibers, which distribute with less marked topography, end in the lateral extreme of the stratum griseum profundum and stratum album profundu

ISSN:0092-7317    

DOI:10.1002/cne.901630405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractA sensitive immunofluorescene technique was used to describe systematically the distribution of dopamine‐β‐hydroxylase (DBH)‐containing cell bodies, non‐terminal fiber pathways, and terminal fields in the brain of the male albino rat. DBH is the enzyme that catalyzes the conversion of dopamine to noradrenaline, and as such is useful as an anatomical marker for noradrenaline and possibly adrenaline neurons. The enzyme is not present in dopamine‐ or indolamine‐containing neurons. Ten micron frozen sections (1‐in‐20 series) were prepared in the frontal, sagittal, and horizontal planes from the olfactory bulb to the upper cervical segments of the spinal cord; adjacent sections in each plane were stained for DBH and for cells (toluidine blue‐azure II). An atlas consisting of 40 projection drawings of selected frontal sections illustrates the results of the investigation. DBH perikarya are confined to three groups in the pons and medulla: the well defined locus coeruleus, a more diffuse but continuous subcoeruleus group that arches through the pons and ventral medulla, and a third dorsal medullary group centered in the dorsal motor nucleus of the vagus. A singleprincipal adrenergic fiber systemdistributes a great many of the axons from these neuron groups to a majority of nuclear areas in the brain. In the pons and medulla two components of the fiber system may be distinguished. Amedullary branchmay be followed from the posterior aspect of the subcoeruleus group dorsally and then anteriorly through the lateral tegmental field and ventral aspect of the vestibular complex to a position subjacent to the locus coeruleus, where it is joined by asubcoeruleus branchconsisting of a large number of fibers coursing among cells along the length of the subcoeruleus group, and by fibers arising from the locus coeruleus. Anterior to the locus coeruleus theprincipal adrenergic bundlecourses as a single fiber tract immediately ventrolateral to the central gray in the mesencephalon and in the zona incerta and substantia innominata in the diencephalon. At the level of the septal area separate bundles reach the cortex dorsally over the genu of the corpus callosum via the medial septal‐diagonal band nuclei and the lateral septum and ventrally between the olfactory tubercle and caudate‐putamen. In the medulla and pons adrenergic fibers undoubtedly course in both directions. Anterior to the most rostral pontine cell bodies, however, all fibers presumably ascend. Along the course of the bundle distinct branches emerge to innervate circumscribed terminal fields. In addition, certain regions of the brain such as the reticular formation and pontine gray receive diffuse DBH innervation derived from less clearly defined pathways. A small number of areas in the brain contain little or no detectable DBH. These include the caudate‐putamen, nucleus accumbens, globus pallidus, olfactory tubercle, subthalamic nucleus, substantia nigra, pretectal area, third, fourth and sixth cranial nerve nuclei, and th

ISSN:0092-7317    

DOI:10.1002/cne.901630406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901630401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY