摘要:

AbstractAnatomical methods which depend upon the anterograde axonal transport of isotopically labeled neuronal proteins or the retrograde axonal transport of the enzyme. Horseradis peroxidase, have been used to elucidate the relationships between the reticular complex and the dorsal thalamus and cerebral cortex. Injections of tritiated amino acide in the dorsal thalamus or cerebrasl cortex in rate, cats and monkey, show that as the bundles of thalamo‐cortical and cortico‐thalamic fibers joining a paarticular dorsal thalamic nucleus to its associated area of the cerebral cortex traverse the reticular complex, they each give rise tp dense zone of terminals occupying a sector of reticular complex which is relatively constant for that dorsal thalamic nucleus and cortical area. However, because of the wide extent of the dendritic fields of the reticular cells and the degree of overlap between the sectors of the complex subtended by adjacent dorsal thalamic nuclei and adjacent cortical areas, it is likely that the reticular complex samples thalamo‐cortical and cortico‐thalamic activity in a somewhat unspecific manner. Fibers passing to the reticular complex from the intralaminar nuclei of the thalamus appear to be associated with the projection from the intralaminar nuclei of the thalamus appear to be associatied with the projection from the intralaminar nuclei to the striatu.Injections of tritiated amino acids in the reticular complex itself and injections of horseradish peroxidase in various other parts of the brain show that the only efferent pathway from thr reticular complex terminates in the nuclei of the dorsal thalamus. The reticdular complex does not appear to send fibers to other components of the ventral thalamus nor to the cerebral

ISSN:0092-7317    

DOI:10.1002/cne.901620302

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

年代:1975

数据来源: WILEY

摘要:

AbstractMetamorphosis in the flatfish is characterized by the migration of one eye around the dorsal surface of the head to a position adjacent to the other eye on the new top side of the animal. The visual connections of the adult flatfish, Achirus lineatus, were examined. Either the migrating or non‐migrating eye was removed and the animal allowed to survive for one to three weeks. Alternate sections of the brain were stained by a modification of the Fink‐Heimer technique, or with cresyl violet. The diencephalc visual connections of the flatfish were similar to those of other teleosts with contralateral projections to the nuclei corticalis, dorsomedialis thalmi, pretectalis, and the corpus geniculatum laterale. The distribution of the retinal efferents to the optic tectum is unique in the flatfish. In the medial one‐third of the tectum, terminal degeneration was found in three bands in the stratum opticum (SO) and the stratum griseum et fibrosum superficiale (sgfs). In the middle part of the tectum, two bands of degeneration remained over the sgfs. The lateral part of the tectum has only a very small amount of degeneration distributed randomly in scattered clusters over the deep SO and superficial sgfs. The Nissl preparations also reflected the differences between the medial and lateral parts of the tectum. Distinct layer was lacking in the medial tectum with a conspicuously absent large cell layer in the stratum griseum centrale (sgc), In contrast, the lateral tectum had a typical tectal stratification. Most notable were the large neurons of th

ISSN:0092-7317    

DOI:10.1002/cne.901620303

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe number and size of the axons in the lateral olfactory tract of the rat have been measured at several rostro‐caudal levels, from material prepared for electron microscopy. Immediately caudal to the olfactory peduncle, an average of 42,000 ± 3,000 axons were counted in the tract, while near the caudal limit of the tract an averge of 32,000 ± 2,800 axons were counted. The average internal cross‐sectional area of axons measured at two levels of the tract was 1.6 ± 1.3 μm2and 1.1 ± 0.9 μ2, corresponding to averge internal diameters 1.4 ± 1.3 μm and 1.2 ± 1.1 μ, respectively. The axons in the lateral part of the tract were found to be significantly larger than those in the medial part of the tract; for one level the average cross‐sectional area of axons in the lateral part of the tract was 1.6 ± 1.0 μm2(equivalent diameter 1.4 ± 1.1 μm) while only 0.7 ± 0.6 μm2(equivalent diameter 0.9 ± 0.9 μm) in the medial part of the tract. The thickness of the myelin sheath of the axons is generally related to axon diameter, increasing from 0.1–0.2 μm for axons 0.4 to 0.8 μm in diameter to 0.3–0.4 μm for axons greater than 2.0 μm in diameter. The ratio of the inside diameter to the outside diameter of the fiber (ratio “g”) is between 0.7 and 0.8 for most axons in the lateral olfactory tract.The axons which leave the tract laterally and medially are substantially smaller than the axons within the tract (average cross‐sectional area 0.55 ± 0.35 μm2on the lateral side) and probably are collaterals of the axons within the tract. Unmyelinated nerve processes, probably axons, were also found in the tract.Qualitative observations from light and electron microscopical material agree well with the quantitative data, and further suggest that mixing of axons from different parts of the olfactory bulb occurs in the rostral part of the tract. This is supported by experiments with injections of3H‐amimo acids into localized portions of the olfactory bulb. These indicate that there is some degree of point‐to‐point organization in the most rostral part of the tract, but that this is lost

ISSN:0092-7317    

DOI:10.1002/cne.901620304

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe cytology of rubral neurons was investigated using both paraffin and 1 μ thick Epon sections. The neurons were divided into four size categories which form a continuum with regard to cellular characteristics. Giant neurons (>40 μ) and large neurons (26–40 μ) predominate in the caudal one‐third of the nucleus. Large neurons extend up the ventral, medial and lateral borders of the nucleus into its middle one‐third. The caudal one‐third of the nucleus together with this extension of large cells is designated as the magnocellular part of the nucleus. The more rostral part of the nucleus con tains predominantly small (<20μ) and medium size (20–25 μ) neurons, and this constitutes the parvocellular part or the nucleus. The characteristics of each cell type are described. Camera lucida drawings of the rubral neurons were made in three different planes of section, and the extent of the magnocellular and parvocellular portions of the nucleus was determined. Dorsomedial and ventrolateral subgroups of the manocellular part of the nucleus are found 300–400 μ from the caudal pole. A lateral horn of small and medium size neurons with the addition of a few large neuraons extends from the lateral part of the nucleus 500–700 μ from the caudal pole.Golgi preparations of the red nucleus were examined in three planes of section. Giant and large neurons display short spines on the soma and also, along the entire length of the dendrites. In addition, more elongate spinous processes are seen on these dendrites and are frequently aggregated into tufts at loci on the dendrites or at their terminations. The dendrites of these neurons radiate in all directions from the soma but remain within the confines of the nucleus. Medium size neurons demonstrate radially arranged dendrites. Sparsely positioned spines are seen along the length of the dendrites but are absent on the soma. A number of such neurons demonstrate tufts of elongate spines on their dendrites. The dendrites. The dendrotes of such neurons branch infrequently and remain within the confines of the nucleus. A few dendritic but no somatic spines are seen in associatio

ISSN:0092-7317    

DOI:10.1002/cne.901620305

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe red nuclei of 14 adult male rats of the Wistar strain were prepared for electron microscopic study following perfusion with a mixture of aldehydes. Neurons of four size categories were identified in 1 μ Epon sections and their ultrastructural characteristics were studied in adjacent thin sections. Giant (>40 μ) and large (20–40 μ) neurons are distinguished primarily by size and possess similar ultrastructural features: extensive areas of rough endoplasmic reticulum (RER), a prominent perinuclear Golgi complex, numerous mitochondria and pigment granules and a large, ovoid nucleus which occasionally contains intranuclear rodlets. Medium size neurons (20–25 μ) have less extensive, poorly organized RER and randomly distributed Golgi complexes. The nuclear envelopes of these cells fraquently show multiple invaginations and continuity with the RER cisternae. In small neurons (<20μ) the RER occurs as single or anastomosing strands while Golgi complexes and pigment granules are few. In both medium size and small neurons, aggregates of condensed chromatin are adherent to the inner nuclear membrane.Three main types of synaptic terminals may be distinguished in the red nucleus: (1) small terminals with flattened vesicles and symmetrical densties (F terminals), (2) small terminals with rounded vesicles and asymmetrical densities (RS terminals), and (3) large (10–15 μ) asymmetrical, rounded vesical terminals which form multiple contacts along their length (RL terminals). The small neurons receive both F and RS terminals on their dendrites and infrequently on their cell somes. The large and giant neurons receive F, RS and RL terminals on their somes and proximal dendrites and F and RS terminals on their distal dendrites. The somas and dendrites of medium size neurons receive both F and RS terminals but RL terminals do not lie in relation to them. Spine contacts are common throughout the nucleus and occur on both somas an

ISSN:0092-7317    

DOI:10.1002/cne.901620306

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe present study is an electron microscopic analysis of the numbers and sizes of axons in the connectives and nerves of the medicianal leech. In either the right or left connectives for ganglis 14–18, there are approximately 2860 (± 294 S.D) axons. Ninety‐seven percent of these axons are less than one micron in diameter. The median connective, Faivre's nerve, contains 97 (± 3 S.D.) axons, and 94% of these fibers are smaller than one micron. In the peripheral nerve roots for ganglia 14–18, there are approximately 2351 (± 311 S.D.) axons. Ninety‐eight percent of the axons in the nerves are less than one micron in diameter. Thus, there are approximately 20,000 axons associated with each of the segmental ganglia 14–18 in the leech, and the vast majority of these fibers are less than one micron

ISSN:0092-7317    

DOI:10.1002/cne.901620307

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

年代:1975

数据来源: WILEY

摘要:

AbstractThis Golgi study identifies three neuronal cell types in the substantia gelatinosa (SG) layer of the spinal trigeminal nucleus. The SG neurons are distinguished from each other based on: (1) dendritic branching pattern, (2) dendritic spine distribution, (3) geometric shape of the dendritic tree, (4) laminar distribution of the dendrites, (5) axonal branching pattern and (6) laminar distribution of the axonal arbor.The islet cell is found in small clusters and its dendrites and axonal arbor are confined within the SG layer. Its dendrites span the full width of the SG layer and extend up to 500 μm in the layer. Dendritic spines are generally sparse with small clustrs of spines found on the higher order dendritic branches. The islet cell axon extends for at least 1 mm in the long axis of the layer. Each of its collaterals divide every 50–100 μm with one branch doubling back in the direction of the cell body and the other branch continuing on in the direction of its parent. In this manner each islet cell generates a profuse axonal plexus in the SG layer.The stalked cell is found individually within the SG layer. Its cell body is usually found in the inner half of the SG layer and its sinuous dendrites cross the SG layer and enter the marginal layer. The stalked cell dendrites emit numerous fine stalk‐like branches and dendritic spines. Its axon emits branches in the SG and marginal layers.The spiny cell is found singly between groups of islet cells. Its extensive dendritic tree spans up to 500 μ rostrocaudally and mediolaterally crossing into both the marginal and magnocellular layers. Spiny cells have evenly distributed dendritic spines along their dendrites in the SG layer. The spiny cell axon sends branches into all three layers of nucleus caudalis. Numerous branches enter the outer 300 μm of the magnocellular layer where they undergo further branching with some branches returing in recurrent fashion toward the SG layer.The three neuronal cell types of the SG layer satisfy all of the morphological criteria for Golgi type II interneurons. Their dendrites are confined within small foci in nucleus caudalis. Their highly branched axone generate many collaterals within the confines of their dendritic trees and do not project out of nucleus caudalis. The SG neurons are considered to be inhibitory interneurons interposed between V nerve primary afferent axons which arborize in the SG layer and second order projection neurons of nucleus c

ISSN:0092-7317    

DOI:10.1002/cne.901620308

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.901620301

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

年代:1975

数据来源: WILEY