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  • Spinal cord  (2)
  • Central nervous system  (1)
  • Corticospinal tract  (1)
  • 1
    Electronic Resource
    Electronic Resource
    On the development of the spinal cord of the clawed frog, Xenopus laevis (1982)
    Springer
    Anatomy and embryology 164 (1982), S. 427-441 
    Details
    ISSN: 1432-0568
    Keywords: Spinal cord ; Morphogenesis ; Histogenesis ; Amphibia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphogenesis and histogenesis of the spinal cord of Xenopus were examined. The study encompasses the developmental period between stage 41 and stage 66 (stages according to Nieuwkoop and Faber 1967). This period can roughly be divided into three phases. From stage 50 up to stage 53 strong proliferation and rapid growth are the most striking features. This developmental phase is preceded and followed by less dynamic periods. From stage 41 up to stage 50 the rate of proliferation is relatively low. The numbers of cells in the matrix and in the mantle layer are very small. In the mantle layer two classes of early differentiated transient neurons can be distinguished: primitive giant sensory or Rohon-Beard cells and primitive motor neurons. From stage 46 onward the originally tube-shaped spinal cord swells at the thoracic level into a thoracic enlargement. After stage 50 the proliferation strongly increases until a maximum at stage 53. Concomitantly a considerable acceleration of growth takes place. The major part of the mitoses are always concentrated in the dorsal part of the matrix. From stage 51 onward the cervical and lumbar regions show much more mitoses than the thoracic part. Distinct cervical and lumbar enlargements develop and are going to mask the thoracic swelling of the cord. From stage 54 on proliferation continues on an increasingly low level. The period between stage 54 and stage 66 is characterized by differentiation of the spinal neuronal elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315763
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  • 2
    Electronic Resource
    Electronic Resource
    The brain of the crossopterygian fish Latimeria chalumnae: A survey of its gross structure (1977)
    Springer
    Anatomy and embryology 151 (1977), S. 157-169 
    Details
    ISSN: 1432-0568
    Keywords: Central nervous system ; Crossopterygii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The macroscopic anatomy of the brain of the single surviving crossopterygian species Latimeria chalumnae is described and depicted. The brain of this fish is slender and elongated. The rhombencephalon is well developed; its ventricular aspect shows four longitudinally arranged ridges which roughly correspond to the functional zones of Herrick and Johnston. The cerebellum comprises two extremely large auriculae and an unpaired, evaginated corpus cerebelli. The mesencephalon is small and does not show any marked differentiation of its surface. In the diencephalon, ventricular sulci mark the boundaries between the epithalamus, dorsal thalamus, ventral thalamus and hypothalamus. The dorsal thalamus protrudes into the ventricular cavity. The telencephalon can be clearly divided into a dorsal pallium and a ventral subpallium. The pallium is represented by a thickened, solid body. It is partly covered by a membranous roof, which in the median plane constitutes an ependymal septum. The subpallium is thin-walled and clearly evaginated. This structure and the ventral part of the pallium enclose a distinct lateral ventricle. The olfactory bulbs are connected with the telencephalon proper by extremely long olfactory peduncles. Interestingly, the brain of Latimeria appears to have gross structural features in common with all major groups of fish, i.e. the Chondrichthyes or cartilaginous fishes, the Dipnoi or lung fishes and the Actinopterygii or ray-finned fishes. Thus, with respect to the shape of the rhombencephalon and of the vestibulolateral lobe of the cerebellum, Latimeria approaches the chondrichthyan condition; the mesencephalon, the diencephalon and the subpallial parts of the telencephalon share a number of features with their dipnoan homologues, whereas the corpus cerebelli, the pallium and the membranous parts of the telencephalon clearly resemble the corresponding structures in the actinopterygians. No special structural affinities to the amphibians were noticed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297478
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  • 3
    Electronic Resource
    Electronic Resource
    On the development of the spinal cord of the clawed frog, Xenopus laevis (1982)
    Springer
    Anatomy and embryology 164 (1982), S. 443-454 
    Details
    ISSN: 1432-0568
    Keywords: Spinal cord ; Differentiation ; Migration ; 3H-Thymidine autoradiography ; Amphibia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary in order to determine the time and site of origin and the final location of various cell groups in the spinal cord, tadpoles of Xenopus laevis, ranging from stage 48 to stage 56 were treated with tritiated thymidine and sacrified at various stages from 49 to 66 (stages according to Nieuwkoop and Faber (1967). From the poorly developed matrix at stage 48–49 not only ventral horn cells, but also neuroblasts of the intermediate zone and the dorsal horn arise. Both the matrix and the ventricle expand in a dorsal direction. From the well-developed matrix at stage 54, in which the mitotic activity is almost exclusively confined to its dorsal part, mainly cells of the dorsal horn develop. However, this later-stage matrix also gives rise to a considerable number of neuroblasts, which become located in the central parts of the intermediate zone and the ventral horn. Generally the later-born cells come to lie dorsomedially to the older ones. The neuroblasts of the lateral motor column, however, migrate through and settle ventrolaterally to their predecessors. Our observations do not support the basal plate-alar plate concept of His (1893).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315764
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  • 4
    Electronic Resource
    Electronic Resource
    On the development of the pyramidal tract in the rat (1986)
    Springer
    Anatomy and embryology 175 (1986), S. 101-110 
    Details
    ISSN: 1432-0568
    Keywords: Corticospinal tract ; Development ; Anterograde tracing ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An anterograde tracer study has been made of the developing corticospinal tract (CST) in the rat using wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP). Analysis of normal Rager stained material revealed that corticospinal axons reach upper cervical spinal cord levels at the day of birth (PO). Postnatal rats ranging in age from one (P1) to fourteen (P14) days received multiple WGA-HRP injections into the cortex of their left hemisphere and were allowed to survive for 24 h. The first labeled CST fibers caudally extend into the third thoracic spinal cord segment at P1; into the eighth thoracic segment at P3; into the first or second lumbar segment at P7 and into the second to third sacral segment at Pg. Thus the outgrowth of the leading ‘pioneer’ fibers of the CST is completed at P9 but later developing axons are continuously added even beyond P9. Quantitative analysis of the amount of label along the length of the outgrowing CST revealed a characteristic pattern of labeling varying with age. The most striking features of that pattern are: (1) the formation of two standing peaks at the level of the cervical and lumbar enlargements respectively and (2) the transient presence of a smaller running peak which moves caudally with the front of the outgrowing bundle. The standing peaks are ascribed to the branching of the axon terminals at both intumescences, whereas the running peak probably arises by the accumulation of tracer within the growth cones at the tips of the outgrowing CST axons. Factors such as the number of axons, the varying axon diameters, the branching collaterals, the presence of varicosities, the transport rate of the tracer, the uptake of the tracer at the injection site, which possibly may affect the amount of label present in both the entire bundle and in the individual axons are discussed. Current research is focused upon an analysis of the relation between the site of injection within the cortex and the pattern of labeling of the CST. A delay of two days was found between the arrival of the CST axons at a particular spinal cord level and their outgrowth into the adjacent spinal gray. However, combined HRP and electronmicroscopic experiments are necessary to determine the factors behind the maturation of the CST as well as the maturation of the spinal gray.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315460
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    Paper (German National Licenses)
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