Showing papers by "Ruijin Huang published in 2016"
TL;DR: Results show that the formation of the unique axon root pattern of the accessory nerve is an intrinsic property of the neural tube, which is unable to give rise to the typical accessory nerve root pattern when transplanted to occipital level.
Abstract: The accessory nerve is a cranial nerve, composed of only motor axons, which control neck muscles. Its axons ascend many segments along the lateral surface of the cervical spinal cord and hindbrain. At the level of the first somite, they pass ventrally through the somitic mesoderm into the periphery. The factors governing the unique root trajectory are unknown. Ablation experiments at the accessory nerve outlet points have shown that somites do not regulate the trajectory of the accessory nerve fibres. Factors from the neural tube that may control the longitudinal pathfinding of the accessory nerve fibres were tested by heterotopic transplantations of an occipital neural tube to the cervical and thoracic level. These transplantations resulted in a typical accessory nerve trajectory in the cervical and thoracic spinal cord. In contrast, cervical neural tube grafts were unable to give rise to the typical accessory nerve root pattern when transplanted to occipital level. Our results show that the formation of the unique axon root pattern of the accessory nerve is an intrinsic property of the neural tube.
2 citations
TL;DR: The expression findings suggest that plexins and neuropilins are involved in neurodevelopment of the cranial structures in chick embryos.
Abstract: Semaphorins exert their effects in neuronal and non-neuronal processes by binding with receptors. Both in vitro and in vivo studies have shown that plexin-As (plexin-A1, plexin-A1 and plexin-A1) and neuropilins (Npn-1 and Npn-2) are the binding moieties for class-III semaphorins. These receptors are expressed in a spatially and temporally discontinuous manner during organogenesis and central nervous system (CNS) development in vertebrates. However, the signaling receptors that accompany with the class-III semaphorins to mediate their actions are still poorly characterized. To assess their diverse roles in neural circuit formation, we analyzed the expression patterns of plexin-A1, plexin-A2, plexin-A4, Npn-1 and Npn-2 in the head and brain stem of chick embryos. In developing eye, plexin-A1 expressed in the lens, whereas plexin-A2 and Npn-1 in the periorbital mesenchyme. Plexin-A1 also expressed throughout the otic vesicle but Npn-1 expressed only in the dorsal part. Among the analyzed plexins and neuropilins, only Npn-2 expression was detected in the branchial arches. Npn-2 and plexin-A4 were also expressed in the trigeminal and vago-accessory ganglia. In the hindbrain, all analyzed plexins and neuropilins were expressed by the selective sets of dorsal(dMNs) and ventral exiting motor neurons (vMNs) except plexin-A4 (only dMNs). Interestingly, plexin-A2 and Npn-1 were co-expressed by the similar sets of dMNs and vMNs (trochlear, trigeminal, abducens, glossopharyngeal, vago-accessory and hypoglossal nuclei). These expression findings suggest that plexins and neuropilins are involved in neurodevelopment of the cranial structures in chick embryos.