摘要:

AbstractPropriospinal fiber connections of the cervical motor nuclei were studied in the cat with the Nauta and the Golgi methods. Synaptic boutons belonging to this fiber system were observed and identified under the electron microscope.Lamina IX of the cervical cord receives a large number of fibers from the short ascending and descending propriospinal tracts but only a very restricted number from the long ascending propriospinal tract. Observations with the Golgi method show that these fibers are collaterals derived from axons ascending or descending in the ventrolateral cord. They are of three types of terminal patterns: Fibers terminating in a confined area of lamina IX with repeated branchings, fibers terminating in a wide area of both laminae IX and VIII with short terminal fibers, and simple, unbranched fibers giving off short terminal fibers to cells of laminae IX and VII.In the cervical motor nuclei, it was found that synaptic boutons containing round vesicles usually form asymmetrical synapses with wide synaptic clefts while those containing flattened vesicles form symmetrical synapses with narrow clefts. There are some boutons which contain round synaptic vesicles and make symmetrical synapses. However, they are invariably associated with wide synaptic clefts. In lamina IX of the cervical cord many axodendritic and axosomatic boutons were found to be degenerate after section of the proprispinal fibers. They were filled with either round or flattened vesicles. A few large boutons, filled with round synaptic vesicles and associated with subsynaptic cisternae, were also seen to be degenerate.

ISSN:0092-7317    

DOI:10.1002/cne.901500102

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

年代:1973

数据来源: WILEY

摘要:

AbstractSpecific projections from the lower spinal cord to the ventral motor nucleus of the cervical enlargement were studied in four mammalian species (cat, rabbit, dog and rat) with the Nauta and the Fink‐Heimer methods.Following hemisection of the lower spinal cord a medium amount of degeneration in laminae VII and VIII and scanty degeneration in the dorsolateral part of lamina IX were observed ipsilaterally at the levels from C6 to T2. In contrast, in all of these animals very dense and circumscribed degeneration was seen in a special ventral or ventrolateral cell group of lamina IX, designated here as ventral motor nucleus (VMN). Cytoarchitectonic study shows that this nucleus exists in the ventral or ventrolateral part of lamina IX from the caudal C7 to the rostral T1 segments, attaining the highest development in the C8 segment.Projections of short descending propriospinal fibers and dorsal root fibers to this nucleus were also studied in cats and rabbits. There was a small projection from a neighboring rostral segment, but no termination was found of dorsal root fibers. These results indicate that VMN in the C7 to the T1 segments is a special cell group which receives predominantly a strong projection from the lower cord levels of the same sid

ISSN:0092-7317    

DOI:10.1002/cne.901500103

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

年代:1973

数据来源: WILEY

摘要:

AbstractPrimary visual cortex (area 17) from macaque monkeys, cats and kittens was stained by a rapid Golgi method modified to give optimal preservation of fine structure. Single impregnated neurons were identified in the light microscope, and then cut in serial thin sections for electron microscopy. As in conventional E.M. material, synapses in the Golgi preparations could be classified into types 1 and 2: type 1 synapses possessed round vesicles in the axon and a pronounced postsynaptic opacity; type 2 synapses had smaller, flattened vesicles in the axon and a slight postsynaptic opacity. Synapses onto impregnated cells were identified by the presynaptic opacities (dense projections), and classified as type 1 or 2 according to the shape and size of the vesicles.Pyramidal cells and spiny stellate cells (found in layer 4) had a similar synaptic environment: type 1 synapses occurred only on the spines, while type 2 synapses were found on dendritic shafts, cell bodies, and axon initial segments. Spinefree stellate cells possessed both type 1 and type 2 synapses on the cell body and on the dendritic shafts, the type 2 synapses being most frequent near to, the type 1 synapses far from, the cell body.Synapses formed by the axon terminals of nine cells were located, and were classified as type 1 or 2 on the basis of the thickness of the postsynaptic opacity. The axons of pyramidal and spiny stellate cells formed type 1 synapses; those of spinefree and sparsely spinous cells formed type 2 synapses. In the 12‐day old to 5‐week old kittens, cells corresponding to the spinefree cells of the adult cat did possess spines. These transient spines were commonest on and near the cell body, and were the sites of type 1 synapses.On these and other grounds, the spiny stellate cells of layer 4 were concluded to be closely related to pyramidal cells, and quite distinct from the class of spinefree and sparsely spinous cells. The interpretation of conventional E.M. preparations of cerebral cortex is discus

ISSN:0092-7317    

DOI:10.1002/cne.901500104

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe afferent projections to the olfactory cortical areas from the olfactory bulb and the prepiriform cortex have been studied in the rat, using the autoradiographic method for demonstrating axonal connections. In order to relate closely the results of these experiments to the structure of the olfactory cortical areas, the cytoarchitectonic characteristics of these areas have also been described.The olfactory cortical areas, which receive a direct input from the olfactory bulb, include the anterior olfactory nucleus, the ventral portion of the tenia tects, the olfactory tubercle, the prepiriform cortex, the nucleus of the lateral olfactory tract, the cortical amygdaloid nucleus, and the lateral entorhinal area. All of these areas are composed primarily of pyramidal cells and have three basic layers: a superficial plexiform layer containing the apical dendrites of the pyramidal cells (layer I), a pyramidal cell layer (layer II), and a deeper polymorphic cellular layer (layer III). In each area layer I may be divided into a superficial portion (IA) and a deeper portion (IB).The autoradiographic experiments have shown that all of the olfactory cortical areas receive projections from the prepiriform cortex as well as from the olfactory bulb, and that these two projections have complementary laminar patterns of termination which are the same in every area. Throughout the olfactory cortex the fibers from the olfactory bulb terminate exclusively in layer IA, in relation to the distal segments of the apical dendrite of the pyramidal cells, whereas the fibers from the prepiriform cortex terminate in layer IB, in relation to more proximal segments of the apical dendrites, and also in layer III. The boundary between the two projections within layer I is very sharp, with minimal overlap. In contrast to this precise laminar organization, there is little evidence for a topographical organization within these Projections.

ISSN:0092-7317    

DOI:10.1002/cne.901500105

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

年代:1973

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901500101

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

年代:1973

数据来源: WILEY