Postnatal development of the rat dorsal funiculus

Ks, Chung; Coggeshall, Richard E.

doi:10.1523/jneurosci.07-04-00972.1987

Cited by 20 publications

(10 citation statements)

References 33 publications

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“…It would seem reasonable to expect that the organization of the dorsal columns of the spinal cord would be similar to that for TrV. It has been demonstrated that this pathway contains a mixture of myelinated and unmyelinated primary afferent axons (Chung et al, 1985;Chung and Coggeshall, 1987;Patterson et al, 1989, 19921, but to our knowledge, the distribution of these fibers within the dorsal columns has not been described in detail.…”

Section: Cross-sectional Organization Of Rxv and Trvmentioning

confidence: 78%

Organization of primary afferent axons in the trigeminal sensory root and tract of the rat

et al. 1996

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A combination of immunocytochemical and electron microscopic methods were employed to assess the organization of the trigeminal (V) spinal tract in adult rats. Immunostaining was employed at the light microscopic level to selectively label large myelinated (by using antibodies against neurofilament protein) and small unmyelinated (by using antibodies against calcitonin gene-related peptide) primary afferents. In addition, the plant lectin Bandeiraea simplicifolia-I was employed to histochemically label small unmyelinated primary afferents. Results from these experiments indicated that larger myelinated axons were distributed throughout the cross-sectional extent of the V spinal tract (TrV), whereas smaller fibers were most numerous just below the pial surface. These results were confirmed with quantitative electron microscopy which demonstrated that the central portion of the V sensory root and TrV were composed primarily of larger myelinated fibers, whereas the periphery of the root and the portion of TrV just below the pial surface contained a higher percentage of smaller myelinated and unmyelinated axons. When considered together with results regarding the birthdates of neurochemically defined classes of V ganglion cells (White et al. [1994] J. Comp. Neurol. 350:397-411), these results suggest that TrV is laid down in a chronotopic fashion with the first axons forming its deeper portion and later arriving axons being added more superficially.

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Section: Cross-sectional Organization Of Rxv and Trvmentioning

confidence: 78%

Organization of primary afferent axons in the trigeminal sensory root and tract of the rat

et al. 1996

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“…3), and MOG (data not shown). This makes sense because the dorsal columns have larger myelinated fibers than does the CST (Chung and Coggeshall 1987); smaller myelinated fibers have thinner myelin sheaths and shorter internodal lengths (Hildebrand 1972;Murray and Blakemore 1980), making the nodal, paranodal, and juxtaparanodal proteins more conspicuous in the CST. Examining longitudinal sections confirmed that nodes were much more common in the CST, and that most of the immunoreactivity was localized to discrete puncta corresponding to nodal, paranodal, and juxtaparanodal regions, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, the overall level of immunoreactivity for nodal, paranodal, and juxtaparanodal proteins was enhanced in the CST (Figs. 1, 2, 3, 4), perhaps because of the diffuse staining of the non-myelinat- (Davis et al 1996), which are also abundant in the CST (Chung and Coggeshall 1987).…”

Section: Resultsmentioning

confidence: 99%

Internodal specializations of myelinated axons in the central nervous system

Arroyo

Poliak

et al. 2001

Cell Tissue Res

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We have examined the localization of contactin-associated protein (Caspr), the Shaker-type potassium channels, Kv1.1 and Kv1.2, their associated beta subunit, Kvbeta2, and Caspr2 in the myelinated fibers of the CNS. Caspr is localized to the paranodal axonal membrane, and Kv1.1, Kv1.2, Kvbeta2 and Caspr2 to the juxtaparanodal membrane. In addition to the paranodal staining, an internodal strand of Caspr staining apposes the inner mesaxon of the myelin sheath. Unlike myelinated axons in the peripheral nervous system, there was no internodal strand of Kv1.1, Kv1.2, Kvbeta2, or Caspr2. Thus, the organization of the nodal, paranodal, and juxtaparanodal axonal membrane is similar in the central and peripheral nervous systems, but the lack of Kv1.1/Kv1.2/Kvbeta2/Caspr2 internodal strands indicates that the oligodendrocyte myelin sheaths lack a trans molecular interaction with axons, an interaction that is present in Schwann cell myelin sheaths.

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“…6, which is published as supporting information on the PNAS web site). However, EphA4 also appeared to be expressed outside the CST, which is confined to the ventromedial aspect of the DF (15). Furthermore, EphA4 was strongly expressed in the ventral DF before the arrival of any CST axons (11): in cervical and lumbar regions of the cord at P0 and in the lumbar cord at P5 (Fig.…”

Section: Epha4 Expression Decreases In the Spinal Cord At The Time Ofmentioning

confidence: 99%

Eph tyrosine kinase receptor EphA4 is required for the topographic mapping of the corticospinal tract

Canty

Greferath²,

Turnley³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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Fine movement in the body is controlled by the motor cortex, which signals in a topographically specific manner to neurons in the spinal cord by means of the corticospinal tract (CST). How the correct topography of the CST is established is unknown. To investigate the possibility that the Eph tyrosine kinase receptor EphA4 is involved in this process, we have traced CST axons in mice in which the EphA4 gene has been deleted. The forelimb subpopulation of CST axons is unaffected in the EphA4 ؊/؊ mice, but the hindlimb subpopulation branches too early within the cord, both temporally and spatially. EphA4 shows a dynamic expression pattern in the environment of the developing CST in the spinal cord: high at the time of forelimb branching and down-regulated before hindlimb branching. To examine whether the fore-and hindlimb subpopulations of CST axons respond differently to EphA4 in their environment, neurons from fore-and hindlimb motor cortex were cultured on a substrate containing EphA4. Neurons from the hindlimb cortex showed reduced branching on the EphA4 substrate compared with their forelimb counterparts. Neurons from the hindlimb cortex express ephrinA5, a high-affinity ligand for EphA4, at higher levels compared with forelimb cortex neurons, and this expression is down-regulated before hindlimb branching. Together, these findings suggest that EphA4 regulates topographic mapping of the CST by controlling the branching of CST axons in the spinal cord.motor control ͉ axon guidance ͉ spinal cord ͉ neuronal development F ine voluntary movement is controlled by the motor areas of the cerebral cortex. The motor cortex has a somatotopic arrangement in which different areas control movements of different parts of the body. For those regions of the motor cortex that control movement of the muscles of the trunk and limbs, the cortical commands travel through the brain in the corticospinal tract (CST) to terminate in topographically specific locations along the spinal cord. There are two major termination zones in the spinal cord, in the cervical and lumbar regions, that carry information for the fore-and hindlimbs, respectively. In primates, the CST axons terminate directly on spinal motor neurons and interneurons, whereas in other mammals, termination occurs almost exclusively on interneurons in the dorsal horns. The CST thus provides the most direct route for cortical control of movement and is the longest and largest descending tract from the brain.During development, growing CST axons must navigate long distances through the brain and spinal cord to reach their gray-matter target cells. How they are successfully guided to their target locations in a topographically correct pattern is unknown. In rodents, CST axons descend through the spinal cord in the ventral aspect of the dorsal funiculus (DF). The axons then exit the DF in topographically specific locations along the cord by means of collateral branching. Several in vivo and in vitro explant studies suggest that as-yet-unidentified diffusible and͞or contact-med...

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Postnatal development of the rat dorsal funiculus

Cited by 20 publications

References 33 publications

Organization of primary afferent axons in the trigeminal sensory root and tract of the rat

Organization of primary afferent axons in the trigeminal sensory root and tract of the rat

Internodal specializations of myelinated axons in the central nervous system

Eph tyrosine kinase receptor EphA4 is required for the topographic mapping of the corticospinal tract

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