摘要:

AbstractUsing Golgi‐stained serial sections obtained at the sacro‐caudal levels of the cat spinal cord, it was possible to reconstruct the trajectory of primary afferents. They were classified into two groups: reliable primary afferents directly traced from the dorsal root and probable primary afferents traced from the dorsal funiculus or Lissauer's tract.The diameters of the reliable primary afferents vary from 0.88–1.88 μm. According to their courses, reliable primary afferents as well as probable primary afferents were classified into three groups: the first is distributed to both medial and lateral halves of the dorsal horn, the second to the medial half, and the third to the lateral half. Commissural fibers were also observed among the probable primary afferents. The rostro‐caudal and medio‐lateral extents of reliable primary afferents are found to be between 250 and 950 μm and 270 and 700 μm respectively, while those of the probable primary afferents were between 125 and 670 μm and 270 and 1,640 μm respectively. These primary afferent fibers are connected with at least two or more laminae of the dorsal ho

ISSN:0092-7317    

DOI:10.1002/cne.901810102

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

年代:1978

数据来源: WILEY

摘要:

AbstractA homologous antiserum directed against rat dopamine‐β‐hydroxylase (DBH) was employed in the indirect immunofluorescence technique of Coons ('58) to describe the distribution and orientation of noradrenergic (NA) axons in the cerebral neocortex of the adult albino rat. DBH is the terminal enzyme in the biosynthesis of noradrenaline and is a sensitive anatomic marker for NA neurons and their processes. Cryostat sections in three standard planes (coronal, sagittal and tangential) taken from four cortical fields (somatosensory, motor, visual and anterior cingulate) were processed for immunofluorescence, and adjacent sections were stained with a Nissl method to relate the pattern of NA axons to specific cortical laminae. Noradrenaline levels and DBH activity were measured in the same cortical fields by radioenzymatic assays.A rich network of DBH immunoreactive axons was observed throughout all cortical layers in each of the areas examined. The pattern of NA distribution is not diffuse, but is characterized by a geometric orderliness that is uniform throughout the neocortex, with only minor regional variations. In layer I the DBH‐positive fibers are predominantly parallel to the pial surface and thus form a tangential grid‐like pattern. Layers II and III are characterized by straight, radial fibers that rarely extend through layer IV to the infragranular layers. There appears to be a NA terminal field in layers IV and V where there is a network of short, oblique or tortuous axon segments, especially prominent in lateral neocortex. Layer VI is unique in that the prevailing orientation of NA fibers is in the anterior‐posterior direction. This band of fibers does not extend into the sub‐cortical white matter, where very few NA fibers are seen. The strong tangential projection of the NA neurons, particularly in layers I and VI, emerges as a dominant feature of this afferent system and appears to be superimposed on the predominantly vertical organization of the cortex. This tangential pattern of organization may allow the locus coeruleus to modulate the activity of adjacent columns synchronously over a vast expanse of cer

ISSN:0092-7317    

DOI:10.1002/cne.901810103

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

年代:1978

数据来源: WILEY

摘要:

AbstractMicroelectrode multiunit mapping studies of parietal cortex in owl monkeys indicate that the classical “primary” somatosensory region (or “SI”) including the separate architectonic fields 3a, 3b, 1, and 2 contains as many as four separate representations of the body rather than one. An analysis of receptive field locations for extensive arrays of closely placed recording sites in parietal cortex which were later related to cortical architecture led to the following conclusions: (1) There are two large systematic representations of the body surface within “SI”. Each is activated by low threshold cutaneous stimuli; one representation is coextensive with Area 3b and the other with Area 1. (2) While each of these representations contain regions of cortex with topological or “somatotopic” transformations of skin surface, the representations have many discontinuities where adjoining skin surfaces are adjoining in the representations. Thus, the representations can be considered as composites of somatotopically organized regions, but cannot be accurately depicted by simple continuous homunculi. Lines of discontinuity often cut across dermatomes and seldom follow dermatomal boundaries, i.e., neither cutaneous representation constitutes a systematic representation of dermatomal skin fields. (3) While the two cutaneous fields are basically similar in organization and are approximate mirror images of each other, they differ in important details, i.e., lines of discontinuity in the representations and the sites of representations of different specific skin surfaces differ significantly in the two representations. (4) The two cutaneous representations also differ in size and in the relative proportions in each representation differ, they cannot both be simple reflections of overall peripheral innervation density. (5) All or part of Area 2 contains a systematic representation of deep body structures.These conclusions are consistent with a view of the anterior parietal region as containing functionally distinct fields at least partially related to different subsets of receptor populations and coding or representing different aspects of somatic sensation. We suggest that the “SI” region of primates be redefined as aparietal somatosensory strip, the Area 1 representation as theposterior cutaneous field, and, for reasons of probable homology with “SI” of other mammals, the Area 3b rep

ISSN:0092-7317    

DOI:10.1002/cne.901810104

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe rat interpeduncular nucleus (IPN) was studied by electron microscopy from the day of birth to 33 days of age. The habenulointerpeduncular (H‐IPN) axons, the principal afferents to IPN, were prominent at birth, occuring in large groups. They formed occasional S synapsesen passantat this time. S synapses subsequently increased progressively in number and maturity until 28 days of age. Crest synapses, also formed by the H‐IPN axons, appeared at eight days without a recognized formative stage. They exhibited their diverse adult morphology by 14 days of age. F synapses, endings of uncertain origin that contain flattened vesicles, were seen at 21 days, although endings containing small vesicles at 14 days represented the same population. Axosomatic synapses were first seen at four days and remained infrequent subsequently. Dendritic growth cones had their maximal prevalence at birth, decreased at four days and were absent by six days of age.Thus each of the four synaptic types previously described in the adult rat IPN exhibited a characteristic time of appearance and pattern of development in normal rat pups. This well‐ordered sequence of synaptogenesis makes the H‐IPN system well suited for a study of synaptic pla

ISSN:0092-7317    

DOI:10.1002/cne.901810105

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

年代:1978

数据来源: WILEY

摘要:

AbstractChanges in the normal synaptogenetic pattern of the interpeduncular nucleus (IPN) were induced by destruction of one or both habenular nuclei in neonatal rats. The S synapses, the principal habenulointerpeduncular (H‐IPN) afferents, were reduced in number and delayed in time of appearance by unilateral lesions. They were eliminated by bilateral lesions. The crest synapses, also of habenular origin, appeared at ten days of age and were apparently normal in structure after unilateral lesions. However, this actually represented a change in connectivity, since normal crest synapses are of bilateral origin. Following bilateral habenular lesions abnormal crest synapses appeared at 28 days of age. These had normal postsynaptic structure, but presynaptically were formed by non‐habenular axons, usually of two different types at each crest synapse. Lesions induced an early appearance of F synapses, at three days, instead of the normal time after six days of age. Apparently similar processes containing flattened vesicles formed somatic contacts only in lesioned animals beginning at 21 days of age. The axosomatic synapses which were only occasional appeared in the adult appeared at the normal time in lesioned animals. At 28 days of age in both unilaterally and bilaterally lesioned animals these was an increase in number of somatic synapses. This increase was due to an increase of the normal somatic endings plus the appearance of somatic synapses containing flattened vesicles. Both types of somatic contacts were found in similar numbers at subsequent ages up to three months.The changes in S synapses represent Wallerian degeneration. The formation of unilaterally derived crest synapses in unilaterally lesioned animals is interpreted as evidence for a specific recognition mechanism. A postsynaptic control mechanism is proposed to explain the formation of heterologous crest synapses, with the usual distinctive geometry but involving abnormal, non‐habenular presynaptic elements four weeks following neonatal bilateral lesions. The increase in axosomatic synapses is unusual since the dendrites of IPN neurons were deafferented, not their somata. The factors leading to the changes in somatic synapses are discussed. The findings reveal new examples of the complexity of neuronal adaptation to CNS lesions in early

ISSN:0092-7317    

DOI:10.1002/cne.901810106

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe anatomy and ultrastructure of the sacculus, lagena, and utriculus of the ear ofPolypterus bichirandScaphirhynchus platorynchuswere studied using the scanning electron microscope. The otolithic organs each contain a single dense calcareous otolith in close contact with a sensory epithelium (macula). The maculae have sensory hair cell typical of those found in other vertebrates, surrounded by microvilli‐covered supporting cells. The hair cells on each macula are divided into several groups, with all of the cells in each group morphologically polarized in the same direction. The cells of the utricular macula in both species are divided into two opposing groups in a pattern similar to that found in other vertebrates. The saccular and lagenar maculae are located in a single large chamber in both species. InScaphirhynchusthe two maculae are on the same plane, while inPolypterusthey are at right angles to one another. The hair cells on the saccular maculae of both species are divided into two oppositely oriented groups. InScaphirhynchusthe cells on the posterior half of the macula are oriented dorsally on the dorsal half of the macula and ventrally on the ventral half. The anterior region of the macula is rotated and the cells of the dorsal and ventral groups are shifted so that they are oriented on the animal's horizontal plane. A similar pattern is found inPolypterus, except that this macula is shaped like a “J” with the vertical portion of the J having horizontal cells and the bottom portion vertical cells. The lagenar maculae in both species have dorsally oriented cells on the anterior side of the macula and ventrally oriented cells on the posterior half of the macula. While these data are not sufficient for clarifying the taxonomic relationship between the two species studied, it is clear that the ears in these species have a number of significant differences from the teleost ear that could have functional and/or taxonomic signifi

ISSN:0092-7317    

DOI:10.1002/cne.901810107

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe visual cortex of the rat was impregnated by the rapid Golgi procedure. From these preparations, smooth (spine‐free) and sparsely‐spined multipolar stellate cells with well impregnated axons were selected and drawn in the light microscope using a camera lucida. Five suitably impregnated cells were then gold‐toned and deimpregnated by removal of the silver chromate produced by the Golgi impregnation, so that they could be examined in the electron microscope to determine both their cytological features and their pre‐ and postsynaptic relationships. A sixth neuron was not deimpregnated, and was examined in the electron microscope only to evaluate the types of synapses formed by its axons terminals. Five of these cells had extensive local axonal plexus and the sixth had a plexus which was less profuse.In the electron microscope the various portions of the deimpregnated neurons were readily identified by their content of fine gold particles, and it was found that their perikarya possessed a rather dark cytoplasm containing many ribosomes. Both symmetric and asymmetric synapses were present on the perikarya, and some of the perikarya had spines. The dendrites of the cells had relatively smooth contours and contained rather closely packed microtubules. The dendrites also had both symmetric and asymmetric synapses along their shafts, with the symmetric synapses being more frequent on the proximal portions of the dendrites.The axons of the neurons were unmyelinated and all of them formed symmetric synapses with their postsynaptic partners. The synapses occurred at dilatations of the axons at both en passant and terminal boutons. Neuronal elements identified as being postsynaptic to the axon terminals of the stellate cells included the perikarya and apical dendritic shafts of pyramidal neurons, the perikarya and dendritic shafts of other stellate cells, and an axons initial segment.Reasons are given for concluding that these multipolar, smooth and sparsely‐spined stellate cells are inhibitory in function, and their relationships with some other neuronal components of the rat visual cortex are c

ISSN:0092-7317    

DOI:10.1002/cne.901810108

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe cerebellar afferents in the bullhead catfish (Teleostei) were labeled by relying on the retrograde transport of horseradish peroxidase (HRP). Retrogradely labeled neurons were seen in: spinal cord, lateral cuneate nucleus, inferior olive, reticular nuclei, vestibular nuclei, nucleus subeminentialis, n. lateralis valvulae, locus coeruleus, n. mesencephalicus dorsalis, the basal optic nuclei, and a nucleus at the isthmic level which may be equivalent to the pontine nuclei of birds and mammals. Inputs to the molecular layer arise from the inferior olive, locus coeruleus and n. lateralis valvulae in addition to subjacent granule cells.No projections to cerebellum were seen to arise from either the optic tectum or from the inferior lobe. The so‐called “lobo‐cerebellar” tract in teleosts was reported by Goldstein, amongst many others, who mistook the superior secondary nucleus for a deep cerebellar

ISSN:0092-7317    

DOI:10.1002/cne.901810109

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

年代:1978

数据来源: WILEY

摘要:

AbstractIn many animals, the optic nerve hasmultipleconduction latency groups of fibres yet displays aunimodalfrequency distribution of fibre sizes. An attempt has been made to resolve this discrepancy in the cat.Examination of teased preparations of fixed cat optic nerve fibres by polarizing interference light microscopy indicated that a fiber's size may change abruptly along its length. Furthermore, the diameters of single nerve fibres followed for distances of up to 30 μm in serial transverse sections of cat optic nerve showed variations of up to 100% of a fibre's average diameter over that distance. On the other hand, the myelin sheath thickness of these fibres appeared to be relatively constant along any one fibres.A population of cat optic nerve fibres which had a unimodal axon diameter frequency distribution was found to have a myelin sheath thickness frequency distribution with five modes. These modes have been interpreted as indicating the existence of five groups of fibres in the cat optic nerve. Four of these groups may be related to four negative peaks seen in the antidromic compound action potential recorded at the margin of the cat optic disc following stimulation of the optic chiasm. The fifth myelin thickness group appears to represent the slowly conducting fibres which do not make an obvious contribution to the antidromic compound action potential.It is concluded that for the cat optic nerve, the conclusion latency groups seen in the compound action potential may be more directly correlated with the frequency distribution of fixed nerve myelin thickness than with the frequency distribution of fixed nerve fibre diameter

ISSN:0092-7317    

DOI:10.1002/cne.901810110

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe pineal of the burrow‐inhabiting, blind goby,Typhlogobius californiensis, was studied by light and electron microscopy. The two predominant cell types were photoreceptor and supportive cells. Ganglion cells could not be positively identified. The majority of photoreceptor cells had well developed outer segments and made apparent synaptic contact with nerve process of unknown origin. Similar unmyelinated nerve fibers containing dense‐cored vesicles were seen descending the pineal stalk. The cytoplasm of supportive cells contained several Golgi zones, occasional dense aggregations of smooth endoplasmic reticulum, abundant quantities of glycogen, some dense‐cored vesicles and unusual rod crystalline inclusions measuring approximately 0.5 μm in width and 4–5 μm in length. These observations suggest that the pineal in this light‐deprived species has retained its photoreceptive function and is a metabolically active organ which may also function i

ISSN:0092-7317    

DOI:10.1002/cne.901810111

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

年代:1978

数据来源: WILEY