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  • Central nervous system  (1)
  • Corticospinal tract  (1)
  • 1
    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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    Paper (German National Licenses)
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  • 2
    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
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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