摘要:

AbstractThe fine structure of the cat's perigeniculate nucleus has been analyzed and compared to that of dorsal thalamic relay nuclei. Golgi preparations and electron micrographs of perigeniculate cells commonly show somatic spines. The most common presynaptic elements for these spines and for the adjacent perikaryal surfaces are relatively large axon terminals containing round synaptic vesicles and making multiple asymmetric contacts. These “RLD” terminals (so termed for theirround vesicles,large average size of the terminals, anddark mitochondria) are also presynaptic to dendritic spines and shafts of proximal and secondary dendrites. Comparisons with adjacent parts of the dorsal lateral geniculate nucleus show that these RLD terminals are cytologically distinct from retinogeniculate terminals and that small numbers of RLD terminals also occur in the geniculate A laminae. Three other major classes of perigeniculate synaptic terminals, resemble major classes of terminals in the dorsal lateral geniculate nucleus. These include two types of terminal withflat or ovoid synaptic vesicles anddark mitochondria, “FD1” and “FD2” terminals, and a class of small terminal with densely clusteredround vesicles anddark mitochondria, “RSD” terminals. RSD terminals, which resemble corticogeniculate axon terminals, represent the only class of perigeniculate terminal that does not contact perikarya. FD2terminals resemble lateral geniculate presynaptic dendrites and participate in serial and triadic synaptic contacts, being both pre‐ and postsynaptic; however, in contrast to the arrangement characteristic of thalamic relay nuclei, these contacts do not occur within synaptic glomeruli. A fifth major class of perigeniculate presynaptic terminal has largeflat or polymorphic synaptic vesicles andpale mitochondria. These “FP” terminals are seen infrequently in the lateral geniculate A laminae. Similarities between perigeniculate and lateral geniculate fine structure may relate in part to common sources of afferent in

ISSN:0092-7317    

DOI:10.1002/cne.902100402

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

年代:1982

数据来源: WILEY

摘要:

AbstractLesions with precisely defined boundaries were made, in adult rat brains, with a new type of cutting device that remained implanted during various survival times. The subsequent events were followed histologically in silverstained (including Fink‐Heimer) horizontal sections, with myelin and nuclear counterstains. The devices, inserted vertically through the dorsal surface of the brain until they met the floor of the skull, consisted of a horizontal cutting wire (0.9–2.6 mm long) between two vertical support wires, all 90 μm diameter. Following fixation of the brain, the device was removed from itsventralsurface; thus, the channels left by the support wires appeared as two holes in horizontal sections, clearly marking the limits of the cut. The extents of the tissue cut by, and that passively deflected around, such devices were charctrized from measurments of brains examined immediately after an incision was made and from degeneration studies after 3‐day implantations. After implantations of 18–230 days, the severed axons no longer abutted the line of such lesions, as seen initially; now axons were often observed to extend alongside the lesion, then to bend and course around the support wire. Such “detours” curved back into the injured tracts, seeming to reconnect them appropriately. Detours had begun by 3–8 days, and end‐swellings were frequently seen on their reoriented axons. Neither collateral sprouting of spared axons nor passive deformation of brain tissue was consistent with the findings. It is concluded that a massive and reconstructive regeneration of cut axons occurred around the ends of lesions made by the

ISSN:0092-7317    

DOI:10.1002/cne.902100403

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe fine structure of primary sensory terminals within glomerular complexes of lamina II of Rexed (substantia gelatinosa Rolandi) in the spinal cord was investigated in normal adult rhesus monkeys and in monkeys subjected to thoracic or lumbosacral dorsal root transection. Three types “scalloped” primary sensory terminals were distinguished on the basis of their ultrastructural characteristics, size, and distribution of synaptic vesicle population: (1) dense sinusoid axon (DSA) terminals contain mediumsized (42–46 nm and 58–62 nm) and large (80 nm) clear synaptic vesicles; (2) large dense‐core vesicles (LDCV) terminals are equipped with empty synaptic vesicles ranging from 30 to 106 nm, large, (80 nm) and very large, (100 nm) dense‐core vesicles; and (3) regular synaptic vesicles (RSV) terminals contain a homogeneous population of 45–50 nm clear synaptic vesicles.Follwing transection of the dorsal roots, all three types of primary afferents degenerate and become engulfed and phagocytosed by glial cells. However, each type of terminal displays a different mode and tempo of degeneration as seen in monkeys sacrificed 36, 48, and 72 hours following rhizotomy. DSAs follow the osmiophilic degeneration pattern; LDCVs are characterized by a gradual increase in the number of “electron‐dense bodies” and, less frequently, by a progressive osmiophilic process; RSVs exhibit signs of a filamentous degeneration, accompanied by clusters of synaptic vesicles.The three types of terminals are distributed in an overlapping but distinct pattern within posterior horn. Thus DSAs are present in highest numbers in lamina II where they constitute the most frequent terminal type. LDCVs also occur in lamina II in its outer half but are most concentrated in lamina I. RSVs predominate in the deepeer layers of the dorsal horn (lamina III) but are also found in the internal half of lamina II. On the basis of these ultrastructural data and a comparison with afferent profiles impregnated according to the Golgi method, it appears that DSAs and LDCVs correspond respectively to superficial and marginal collaterals of small, thin dorsal root fibers whereas RSVs represnt terminals of deep collaterals from large, thic

ISSN:0092-7317    

DOI:10.1002/cne.902100404

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe synaptic glomerular complexes surrounding dorsal root terminals in the substantia gelatinosa were reconstructed from six sets of 50–140 gapless ultrathin serial sections prepared in the transverse plane of the spinal cord in adult rhesus monkeys. All three types of glomeruler terminals described in the preceding paper (Knyihar‐Csillik et al., 1982) were identified: (1) DSA (endings of superificial collaterals); (2) LDCV (endings of marginal collaterals); and (3) RSV (endings of deep collaterals). Each type of terminal forms a glomerular complex which invariably includes presynaptic dendrites which are intercalated between primary terminals and the postsynaptic (conventional) dendrite. Since the latter also receives direct input from the primary sensory terminal the synaptic organization assumes triadic arrangements, suggesting that primary afferent impulses my be subjected to a postsynaptic modulation through inhibitory action of presynaptic dendrites.In glomeruli with DSA as the central element, several triadic systems are usually interrelated, possibly as a structural basis for prolonged retardation of impulses. Adjacent glomeruli, containing DSA and LDCV terminals, are coupled together by a series of triadic systems fed by DSA terminals enabling association between superficial and marginal collaterals. RSV terminals are presynaptic to somata and dendrites of substantia gelatinosa cells that presumably exert inhibition upon terminals of all three kinds of primary sensory collaterals. In addition RSV terminals are postsynaptic to numerous F boutons which presumably derive mainly from axons of substantia gelatinosa cells; similar F boutons impinge upon presynaptic and other dendrites surrounding DSA terminals. The Complicated but orderly synaptic architecture of these three types of primary afferents may be regarded as a structural basis for first‐order analysis and modulation of the nociceptive information within the primate central nervous s

ISSN:0092-7317    

DOI:10.1002/cne.902100405

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe cutaneous innervation of the fo relimb was investigated in 20 bar‐biturate‐anesthetized cats by using electrophysiological techniques. The cutaneous area (CA) innervated by each cutaneous nerve was delineated in at least six cats by brushing the hair in the CA with a small watercolor brush while recording from the nerve. Mapping of adjacent CA revealed larger overlap zones (OZ) than were noted in the dog. Remarkable findings were that the brachiocephalic nerve arose from the axillary nerve and the CA comparable to that supplied by the cutaneous branch of the brachiocephalic nerve in the dog was supplied by a cutaneus branch of the suprascapular nerve. The CA supplied by the communicating branch from the musculocutaneous to the median nerve was similar in both species except that the communicating branch arose proximal to any other branches of the musculocutaneous nerve in the cat, whereas it was a terminal branch in the dog. The superficial branch of the radial nerve gave off cutaneous brachial branches in the cat proximal to the lateral cutaneous antebrachial nerve. The CA of the palmar branches of the ulnar nerve did not completely overlap the CA of the palmar branches of the median nerve as occurred in the dog; thus an autonomous zone (AZ) for the CA of the palmer branches of the median nerve is present in the cat, whereas no AZ existed for the CA of this nerve in the

ISSN:0092-7317    

DOI:10.1002/cne.902100406

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe peroxidase‐antiperoxidase (PAP) technique is used to determine the time of first detection and distribution of neuronal perikarya and processes showing substance P (SP)‐ and enkephalin (EN)‐like immunoreactivity (LI) in the central and peripheral nervous system of the fetal rat. SPLI is first detected in central perikarya at E15. By E18, SPLI is less intensely localized in certain nuclei and shows heavier accumulations of immunoreactivity in central processes in peripheral sensory neurons. ENLI is also widely distributed in perikarya and processes of the central nervous system at E18, but is not detected at E15. The distribution of SPLI and ENLI at E18 is comparable to that previously described in the adult brain with the following exceptions: (1) labeled perikarya and processes are not detected in the rostral forebrain; (2) axonal pathways are intensely labeled whereas most terminal fields are devoid of immunoreact

ISSN:0092-7317    

DOI:10.1002/cne.902100407

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

年代:1982

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902100401

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

年代:1982

数据来源: WILEY