摘要:

AbstractTo examine the fine structure of cells synthesizing DNA in the spinal cord in response to injury, mice were given a single injection of3H‐thymidine two days after stab injury to the spinal cord and were sacrificed at either two hours or one, two, six or 14 days later. The most common type of labeled cell found at a distance from the wound at all the time intervals after3H‐thymidine injection had an elongated or irregularly oval nucleus with clumps of condensed chromatin at the nuclear envelope and one or more nucleoli. The cytoplasm which was darker than adjacent axoplasm, contained dense bodies, scattered mitochondria, many free ribosomes, only a few rather long cisternae of granular endoplasmic reticulum, a prominent Golgi apparatus, and a few granules. These cells were similar in appearance to the cells that have been identified as microglia or multipotential glia by others. However, they also have many features in common with blood mononuclear cells. In the wound, in addition to the cells already described, the labeled cells at two hours after3H‐thymidine injection included well developed macrophages, a few endothelial cells, and a large number of cells with large pale nuclei and cytoplasm containing abundant microtubules and granules. At the later time intervals, these cells apparently developed large numbers of cytoplasmic filaments. Although they bore some resemblance to reactive astrocytes, these labeled cells were not typical astrocytes, and their location, their apparent transformation from a cell without filaments, and their pseudopodia and surface vacuoles suggest the possibility that they may be derived from blood mononuclear

ISSN:0092-7317    

DOI:10.1002/cne.901510102

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

年代:1973

数据来源: WILEY

摘要:

AbstractTo study gliogenesis in the spinal cord, Feulgen cytophotometry was carried out on cells in the cervical cord of human embryos ranging from 7–45 mm in crown‐rump length. Glioblasts synthesizing DNA are first detectable at eight‐week‐stage in the mantle and marginal zones in the basal plate and immediately thereafter in the alar plate. Coincidentally the matrix layer changes into a single‐layered ependymal lining. This pattern of the incipient stage of gliogenesis in the human spinal cord closely resembles that of the chick embryo.Silver carbonate staining of the spinal cord at this stage showed diverse morphology of the glioblasts at their earliest stage of differentiation. The pattern of glioblast formation coincides with that of the genesis of the so‐called microglioblasts so far reported, not only in the space‐time relationships in embryogenesis but also in the morphology of the cells occurring at this stage. It is concluded that the so‐called genesis of the microglia in the spinal cord is nothing but the stage of glioblast formation from t

ISSN:0092-7317    

DOI:10.1002/cne.901510103

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

年代:1973

数据来源: WILEY

摘要:

AbstractElectron microscopic examination of the retina of the axolotl,Ambystoma mexicanum, revealed several types of morphological junctions between individual photoreceptors. Distal to the outer limiting membrane of the retina, gap junctions were found between neighboring rods and between neighboring rods and cones. In the external plexiform layer, the synaptic terminals of cones and double cones are often in positions opposite the synaptic ribbons of rod terminals that have been traditionally defined as postsynaptic. A few tight junctions between photoreceptor telodendria were observed. Relationships between the members of double cones are also described.

ISSN:0092-7317    

DOI:10.1002/cne.901510104

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe central distribution of the posterior lateral line nerve (NLLp) was studied in the weakly electric African fish,Gnathonemus petersii. Lesions were made in the ganglion of NLLp and the degeneration traced by means of the Fink‐Heimer technique. NLLp distributes to the ipsilateral posterior lateral line lobe, anterior lateral line lobe, and lobus caudalis cerebelli. The posterior lateral line lobe is laminated and NLLp terminates in an organized manner within three of its six laminae. In addition the projection of NLLp to the posterior lateral line lobe is topographic. The projection of NLLp to the anterior lateral line lobe is more diffusely organize

ISSN:0092-7317    

DOI:10.1002/cne.901510105

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe central connections of the lateral line nerve ganglia, the eithth nerve ganglia and the fused fifth‐seventh ganglion ofGanathonemus petersiihave been studied with silver degeneration techniques. The anterior (NLLa) and posterior (NLLp) lateral line nerves have a topographically organised projection upon the posterior lateral line lobe. NLLa, representing the head region, distributes to the rostral half of the posterior lobe, while NLLp, representing the trunk, distributes to the caudal half of the posterior lobe. The lateral line nerves also end in the anterior nucleus of the anterior lobe. There is some overlap within the middle third of the anterior nucleus, although NLLp tends to have a more caudal distribution than NLLa. N VIII terminates within n. tangentialis and n. octavius; there appears to be little or no overlap between VIII and lateral line nerve territories.The V–VIIth ganglion projects to entirely different parts of the brainstem. Terminal areas of V–VII are the sensory nucleus of the vagus, the nucleus of the descending trigeminus, and the funicular n

ISSN:0092-7317    

DOI:10.1002/cne.901510106

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

年代:1973

数据来源: WILEY

摘要:

AbstractNeuromuscular junctions on leech body wall muscle have been described. Based on vesicle morphology, there are two types of junctions, (I) clear vesicle terminals, and (II) dense core vesicle terminals. Further, the dense core terminals are‐of two types, (1) small terminals which appear to directly innervate body wall muscle cells, and (2) large terminals which appear to synapse on clear vesicle terminals which in turn innervate body wall muscle cells. The clear vesicle ending resembles known cholinergic junctions in other systems. The cores in the dense core vesicle terminals are regarded as containing 5‐HT because (1) they are structurally identical with the 5‐HT containing cores in granules of the Retzius cells, (2) they contain a chromaffin substance, and (3) they become radioactive when tritiated 5‐HT is present but not when 5‐HTP or noradrenaline i

ISSN:0092-7317    

DOI:10.1002/cne.901510107

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.901510101

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

年代:1973

数据来源: WILEY