摘要:

AbstractIn area 17 of squirrel monkey, lamina IVB of Brodmann is divided into three sublaminae by a thin, dense row of cell bodies, the largest of which have apical poles. Study of the 17/18 border suggests that these are a group of pyramidal cells, continuous with the large border pyramids in the depth of layer III in area 18. In contrast, the densely packed granule cells of layers IVA and IVC appear to be continuous with those of layer IV of area 18. It is thus proposed that in area 17, the third and fourth neocortical layers not only divide into sublaminae, but that these in turn interdigitate and intermingle their cell types. The tangential extent of intracortical fibers has been studied by making perpendicular slits in both areas and measuring the spread of anterograde degeneration to each side of the lesion. In area 17, this spread is always the same whatever the orientation of the fibers with respect to visual field representation. Degenerating fibers are few in number and found mainly in layers I, IVB and VI. In layers IVB and VI they extend for 0.5–1.0 mm. In layer I, some reach as far as 2.0 mm. In area 18, degenerating fibers are more numerous and longer. They are plentiful in layer I, diminish considerably in layer II, increase again in number till the depth of III, are slightly less numerous in layer IV and are again plentiful in layers V and VI. Their length varies with orientation. In a direction corresponding to a visual field sector, they extend for 1.5–2.0 mm, a distance representing only a fraction of the total representation of a sector in the cortex. In a direction corresponding to a visual field zone, they extend further and the combined degeneration of the two sides spans the whole distance of area 18 from the vertical to the horizontal meridian (6 mm). It is suggested that at least some of the fibers of the stria of Gennari subserve binocular interaction and that the differential fiber lengths in area 18 are related to foveal acquisition or to a directional anisotropy of visual movement perception along sector‐zone

ISSN:0092-7317    

DOI:10.1002/cne.901790202

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe distribution of different synaptic types has been analyzed quantitatively in the molecular and subcellular layers of turtle „vislual”︁ cortex. The density of vesicle‐containing‐profiles (VCPs) is 122.2/400 square μm in the molecular layer and 61.0/400 square μm in the subcellular layer. In both layers, approximately 85% of VCPs conatin round vesicles (RVCPs), 12%, flat vesicles (FVCPs) and 1%, dense core vesicles (DVCPs). Vacuolar invaginations (VIs) are not uncommon in the molecular layer (3.4%) but are rare in the subcellular layer (0.6%). Synaptic conatacts are formed in the plane of section by three out of ten RVCPs and FVCPs, while only one out of the 146 DVCPs sampled in this study was associated with a membrane differentiation. In the molecualr layer, the percentage distribution of the different subgroups of synaptic types is as follows: round‐asymmetrical contacts, 82.5% (77.5% on dendritic spines and 5.0% on dendritic shafts); round‐symmetrical contacts, 3.8% (2.3% on spines and 1.5% on shafts);flat‐symmetrical contacts, 13.1% (8.8% on shafts and 4.3% on spines; flatasymmetrical contacts 0.6% (0.4% on spines and 0.2% on shafts)). In the subcellular layer, the distribution is quite different: round‐asymmetrical contacts. 72.4% (38.6% on shafts and 33.8% on spines); round‐symmertical contacts, 12.8% (8.2% on shafts and 4.6% on spines); flat‐symmetrical contacts, 13.9% (9.3% on shafts and 4.6% on spines); flat‐asymmetrical contacts, 0.9% all on dendritic shafts. The density distribution of VCPs in the molecular layer changes with depth. RVCPs are fewer on the distal third of the apical dendrites, and most numerous in the middle third with a small dercease in number in th proximal third. FVCPs are more homogeneously distributed, perhaps increasing slightly in number towards the proximal parts of the dendritets. RVCPs are most numerous on dendritic spines. These spines are of two types whose relative number varies with depth. Large organelle‐filled spines predominate in the upper third while small „empty”︁ spines are most numerous in the l

ISSN:0092-7317    

DOI:10.1002/cne.901790203

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe development of retinal amacrine cells in mice at the fifteenth day of gestation (E‐15) has been analyzed by reconstructing large numbers of cells from serial thin sections. This information has been supplemented by reconstructing cells from E13 and E17 retinas as well as autoradiographic studies of time of origin of cells arising in the period before E15. The presence of bipolar amacrine cells in the outer ventricular layer, first suggested by Cajal, has been confirmed by reconstructing cells from the E17 retina when a clearly defined inner plexiform layer (IPL) is first found. The less mature bipolar amacrine cells present at E17 resemble similar cells found in the E15 retina; they are distinguished from the pre‐axonic, migratory stage of ganglion cells by their flattened rather than cylindrical processes, the darker cytoplasm of these processes, and the position of their centrioles closer to the nucleus. Examination of large numbers of reconstructed cells throughout the thickness of the E15 retina has revealed no forms directly transitional from ventricualr cells to bipolar amacrine cells; insted, bipolar amacrine cells appear to be derived by retrograde (sclerally directed) migration of cells in the ganglion cell layer that resemble normal ganglion cells but lack axons. The origin of these anaxonic cells of the ganglion cell layer is not certain but several findings, including evidence of degenerating axons in the optic nerve, sugest that they are derived by loss of the primitive axons of ganglion cells. Thus amacrine cells may be formed by a relatively late differentiating event that occurs after migration of cells to the ganglion cell layer. Such a developmental origin would offer a plausible explanation for the displaced amacrine cells in the ganglion cell layer and IPL described in the adult, as well as perhaps the close similarity of the dendritic trees of certain subtypes of normal, nondisplaced, ganglion and amacrine ce

ISSN:0092-7317    

DOI:10.1002/cne.901790204

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe developmental sequence of Grandry corpuscles was traced in the toe skin of embryonic, young and adult chickens by light and electron microscopy. The developing Grandry cells as well as Schwann cells can first be identified at stage 38(˜ 12 days of incubation) due to the cytoplasmic content of scattered secretory granules of ˜ 100 nm in diameter. Such developing Grandry cells are always associated with nerve fibers. During late stages (stages 40–42, 14–16 days of incubation) several immature Grandry cells formed cell clusters in the dermis. Such cell clusters were always in contact with growing nerve tips or Schwann cells. Immature Grandry cells were separated from one another and dispersed in the connective tissue compartment at stages 44–45 (near hatching). By the time of hatching the developing Grandry cells began to have the morphological characteristics of adult cells. They were relatively large in cell diameter (˜ 10 μm) containing numerous secretory granules and bundles of filamentous material. These cells had finger‐like cytoplasmic processes. The Grandry cells at this time had an intimate relationship with nerve fibers and satellite cells. The fact that Grandry cells were always associated with nerve fibers throughout deveopment would support the hypothesis that Grandry cells are derived from neural elements, perhaps neural crest. Satellite cells of Grandry corpuscles are apparently derived from Schwann cells. Grandry cells and corpuscles are adult in form by two to three mo

ISSN:0092-7317    

DOI:10.1002/cne.901790205

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

年代:1978

数据来源: WILEY

摘要:

AbstractTechniques of intra‐axonal transport were utilized to elucidate the organization of diencephalic and midbrain projections to the inferior olivary nucleus of the Virginia opossum. Retrograde transport of horseradish peroxidase injected into olive suggests that terminals within it arise from the subparafascicular nucleus of the caudal thalamus, the nucleus of Darkschewitsch, the fields of Forel, the interstitial nucleus of Cajal, the periaqueductal grey, the caudla pretectal nucleus, the tegmentum dorsomedial to the red nucleus, the red nucleus (minimal), the nucleus linearis, as well as the dorsolateral midbrain tegmentum and tectum (Henkel et al., '75).Tritiated leucine injections were made into each of the above‐mentioned cell groups so that the olivary terminals of their axons could be demonstrated autoradiographically. In general, the projection systems show three basic patterns of organization. Ventormedial areas of the midbrain, including the ventral periaqueductal grey, the interstitial nucleus of Cajal, part of the red nucleus and the tegmentum dorso‐medial to it, provide a substantial and topographically organized projection to the principal nucleus of the olive, as well as minor inputs to the accessory neclei. Secondly, neurons within the subparafascicular nucleus, the nucleus of Darkschewitsch and the fields of Forel project most heavily to parts of the medial accessory nucleus, although they also provide input to the other major subdivisions of the olive. Third, axons from the dorsolateral tegmentum and tectum completely avoid the principal nucleus, while supplying small regions of the accessory n

ISSN:0092-7317    

DOI:10.1002/cne.901790206

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe retrograde transport of horseradish peroxidase was utilized to map olivo‐cerebellar projections in the Virginia opossum. The spinal cerebellum (anterior lobe, paramedian lobule and pyramis) receive input from several separate regions in the dorsal accessory nucleus, the medial accessory nucleus and portions of the principal nucleus. Evidence is present for a topographical organization whereby specific regions of the olive project to restricted longitudinal zones. The visual‐auditory region of the posterior vermis receives input from small areas within the caudal part of the medial accessory nucleus. From a distinctly separate region of the caudal part of the medial accesssory nucleus (as well as the principle nucleus), axons project to the uvula. The vestibulo‐cerebellum is the recipient of axons from the cap of Kooy and from two spatially separate regions of the medial accessory nucleus. The cerebellar hemisphere(Crus I and II, lobus simplex) is the target of axons from the different nuclei are targeted upon separate zones. The paraflocculus was found to receive an input from the rostral part of the medial accessory nucleus and from the principal nucleus.The present relsults suggest that a distinct olivary region may project to several widely separate areas of the cerebellum, and that one cerebellar region may revieve input from several areas of the olive. The organization of the olivocerebellar projection is highly complex, but when considered in light of known inputs to the olive, certain patterns e

ISSN:0092-7317    

DOI:10.1002/cne.901790207

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

年代:1978

数据来源: WILEY

摘要:

AbstractIn the cat, a spinal projection to a restricted area of the basilar pontine grey has been revealed with use of an anterograde degeneration technique (Fink‐Heimer). The area was ipsilateral to the spinal lesion, restricted to the far caudal limit of the pons, and included the dorsal and the dorsolateral subdivisions of the pontine nuclei (PN). Comparisons following high cervical, midthoracic and upper lumbar spinal lesions did not reveal any somatotopic organization. Only a few spinopontine fibers had origins below segmental level L4. Lesions of various quadrants of the cord indicated that the spinopontine fibers ascendede through the dorsolateral funiculus, and not through either the dorsal or the verntal funiculi. Comparison with the degeneration effects of cerebral cortical lesions showed that the spinal projection from the first sensorimotor and second somatosensory cortices. In the rat no comparable spinopontine projection was found.It is suggested that the spinopontine pathway migh forward information to the cerebellum from visceral sensory receptors or perhaps from pools of spinal interneuron

ISSN:0092-7317    

DOI:10.1002/cne.901790208

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

年代:1978

数据来源: WILEY

摘要:

AbstractFollowing injections of horseradish peroxidase in the oculomotor and the trochlear nuclei in the hen, the occurrence of labeled cells was plotted in the vestibular nuclei. The majority of labeled cells was localized in the superior, the medial, and the tangential nucleus. Within the superior nucleus the cells were found mainly caudally, extending medially and ventrally in central areas. In the medial nucleus labeled cells were localized exclusively in its rostral half, mainly in ventrolanteral regions. Most, if not all, cells in the nucleus tangentialis project rostrally. In addition, rostrally projecting vestibular cells were found in the cell group A and the rosrolateral part of the descending nucleus. The projection to the oculomotor nuclear complex is from the superior nucleus and the cell group A bilateral but chiefly ipsilateral, from the medial nucleus bilateral, from, the tangential nucleus and the rostral pole of the descending nucleus chiefly contralateral. Massive labeling was found in the abducens nucleus, somewhat less in the reticular formation, mainly in lateral regions of the medial part at the level of the abducens and facial nuclei. Labeled cells were, in addition, found in the deep layers of the optic tectum, and scattered cells in the nucleus raphe. The findings are discussed in the light of what is known of the organization of the vestibular nuclei in the hen and the rostral projection of the vestibular nuclei in mammals.

ISSN:0092-7317    

DOI:10.1002/cne.901790209

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

年代:1978

数据来源: WILEY

摘要:

AbstractA recently developed fluorescence histochemical technique, which both fixes the brain in situ and converts catecholamines to fluorescent derivatives, has been utilised to study the distribution of catecholamine‐conataining cell bodies in the central nervous system of the rabbit, a species particularly suited to cardiovascular investigation.Catecholamine‐conataining cells are widely distributed through the brain stem but are absent from the spinal cord, the cerbellum and the telencephalon. In the medulla the cells form separate ventrolateral and dorsomedial groups, while pontine cells form a continuous gruop, comprising cells of the locus coeruleus, the subcoeruleus and the ventrolateral pontine area. Fluorescent cella are widely distributed in the midbrain including an extensive group in the substantia nigra and a smaller dorsal group in the central gray matter just ventral to the aqueduct. Nearly all fluorescent forebrain cells are found in the hypothalamus, in the arcuate nucleus and in the more caudal reigons of the dorsal hypothalamus.Although the general arragement of the catecholamine‐containing cells is similar to that of the rat there are some readily appreciated differences. Ventrolateral medullary cells are more tightly grouped in the rabbit and dorsomedial medullary cells extend forther rostrally, some being found within the dorsal motor nucleus of the vagus. Locus coeruleus cells are more loosely arranged in the rabbit and the subcoeruleus group is more extensive. Midbrain cells are closely comparable but the caudal thalamic group described in the rat is less extensive in the r

ISSN:0092-7317    

DOI:10.1002/cne.901790210

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

年代:1978

数据来源: WILEY

摘要:

AbstractMicroelectrode mapping methods were used to determine the organization of primary somatosensory cortex, SmI, in grey squirrels. A systematic representation of the contralateral body surface was found within somatic koniocortex. This primary representation differs from maps of SmI in other mammals in at least two significant ways. The first way in which SmI of squirrels differs from the organization reproted for other mammals is that SmI of squirrels contains a double representation of the hand and parts of the forearm. The glabrous skin of the digits is represented twice in a mirror image fashion joined at the finger tips. The hairy skin of the digits, wrist, and parts of the forearm are also represented twice, once on each side of the joined representations of the glabrous skin. A second unique feature of SmI squirrels is that there is a small region of cortex completely surrounded by SmI that was unresponsive to light cutaneous stimuli under our recording conditions. This unresponsive zone is easily identified in brain sections by architectonic features that deviate from sensory koniocortex and approach motor cortex. A third significant finding was that the back is rostral to the belly in the representation of the trunk in SmI of squirrels. This is the reverse of the orientation reported elsewhere for SmI of mammals, but corresponds to the orientation of the trunk representation in Area 3b of owl monkey (Kaas et al., '76; Merzenich et al., '78). This similarity supports and earlier contention that the representation of the body in Area 3b of primates is the homolog of SmI in other mammals (Merzenich et al., '78).

ISSN:0092-7317    

DOI:10.1002/cne.901790211

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

年代:1978

数据来源: WILEY