scholarly journals The developmental hourglass model is applicable to the spinal cord

2021 ◽  
Author(s):  
Katsuki Mukaigasa ◽  
Chie Sakuma ◽  
Hiroyuki Yaginuma
Keyword(s):  
Spinal Cord ◽  
Regulatory Elements ◽  
Spinal Neurons ◽  
Upstream Gene ◽  
Spinal Cord Development ◽  
Neuronal Progenitor ◽  
Before And After ◽  
Hourglass Model ◽  
Fate Determinants ◽  
Developmental Hourglass

SummaryThe developmental hourglass model predict that embryonic morphology is most conserved at mid-embryonic stage and diverge at early and late stage. This model is generally considered by whole embryonic level. Here, we demonstrate that the hourglass model is also applicable to the more reduced element, the spinal cord. In the middle of the spinal cord development, dorsoventrally arrayed neuronal progenitor domains are established, which is conserved among vertebrates. We found that, by comparing the single-cell transcriptomes between mice and zebrafish, V3 interneurons, a subpopulation of the post-mitotic spinal neurons, display the divergent molecular profiles. We also found non-conservation of cis-regulatory elements located around the progenitor fate determinants, indicating the rewiring of the upstream gene regulatory network. These results demonstrate that, despite the conservation of the progenitor domains, processes before and after the progenitor domain specification has diverged. This study may help understand the molecular basis of the developmental hourglass model.

scholarly journals Basal protrusions mediate spatiotemporal patterns of spinal neuron differentiation

2019 ◽  
Author(s):  
Zena Hadjivasiliou ◽  
Rachel Moore ◽  
Rebecca McIntosh ◽  
Gabriel Galea ◽  
Jon Clarke ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Periodic Pattern ◽  
Spinal Neuron ◽  
Spatiotemporal Pattern ◽  
Spinal Neurons ◽  
Long Distance ◽  
Basal Surface ◽  
Spinal Cord Development ◽  
Model Support

SummaryDuring early spinal cord development, neurons of particular subtypes differentiate with a sparse periodic pattern while later neurons differentiate in the intervening space to eventually produce continuous columns of similar neurons. The mechanisms that regulate this spatiotemporal pattern are unknown. In vivo imaging of zebrafish reveals differentiating spinal neurons transiently extend two long protrusions along the basal surface of the spinal cord prior to axon initiation. These protrusions express Delta protein consistent with the possibility they influence Notch signalling at a distance of several cell diameters. Experimental reduction of laminin expression leads to smaller protrusions and shorter distances between differentiating neurons. The experimental data and a theoretical model support the proposal that the pattern of neuronal differentiation is regulated by transient basal protrusions that deliver temporally controlled lateral inhibition mediated at a distance. This work uncovers novel, stereotyped protrusive activity of new-born neurons that organizes long distance spatiotemporal patterning of differentiation.

An Early Developmental Marker for Radial Glia in Rat Spinal Cord

1996 ◽  
Vol 54 ◽  
pp. 36-37
Author(s):  
V. Kriho ◽  
H.-Y. Yang ◽  
C.-M. Lue ◽  
N. Lieska ◽  
G. D. Pappas
Keyword(s):  
Spinal Cord ◽  
Intermediate Filament ◽  
Radial Glia ◽  
Rat Spinal Cord ◽  
Future Studies ◽  
Spinal Cord Development ◽  
Median Septum ◽  
Differentiation Marker ◽  
Early Developmental ◽  
Developing Rat

Radial glia have been classically defined as those early glial cells that radially span their thin processes from the ventricular to the pial surfaces in the developing central nervous system. These radial glia constitute a transient cell population, disappearing, for the most part, by the end of the period of neuronal migration. Traditionally, it has been difficult to definitively identify these cells because the principal criteria available were morphologic only.Using immunofluorescence microscopy, we have previously defined a phenotype for radial glia in rat spinal cord based upon the sequential expression of vimentin, glial fibrillary acidic protein and an intermediate filament-associated protein, IFAP-70/280kD. We report here the application of another intermediate filament-associated protein, IFAP-300kD, originally identified in BHK-21 cells, to the immunofluorescence study of radial glia in the developing rat spinal cord.Results showed that IFAP-300kD appeared very early in rat spinal cord development. In fact by embryonic day 13, IFAP-300kD immunoreactivity was already at its peak and was observed in most of the radial glia which span the spinal cord from the ventricular to the subpial surfaces (Fig. 1). Interestingly, from this time, IFAP-300kD immunoreactivity diminished rapidly in a dorsal to ventral manner, so that by embryonic day 16 it was detectable only in the maturing macroglial cells in the marginal zone of the spinal cord and the dorsal median septum (Fig. 2). By birth, the spinal cord was essentially immuno-negative for this IFAP. Thus, IFAP-300kD appears to be another differentiation marker available for future studies of gliogenesis, especially for the early stages of radial glia differentiation.

The effect of the Standard American Diet on Iba-1 immunoreactivity in the spinal cord before and after peripheral inflammatory injury in rats

2021 ◽  
Vol 18 ◽  
pp. 100278
Author(s):  
Larissa J. Strath ◽  
Stacie K. Totsch ◽  
Tammie L. Quinn ◽  
Marissa Menard ◽  
Alan Philip George ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Inflammatory Injury ◽  
Before And After

scholarly journals Glycine Release from Radial Cells Modulates the Spontaneous Activity and Its Propagation during Early Spinal Cord Development

2010 ◽  
Vol 30 (1) ◽  
pp. 390-403 ◽  
Author(s):  
A.-L. Scain ◽  
H. Le Corronc ◽  
A.-E. Allain ◽  
E. Muller ◽  
J.-M. Rigo ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spontaneous Activity ◽  
Spinal Cord Development ◽  
Glycine Release

Motor projection patterns to the hind limb of normal and paralysed chick embryos

Development ◽  
1982 ◽  
Vol 72 (1) ◽  
pp. 269-286
Author(s):  
N. G. Laing
Keyword(s):  
Spinal Cord ◽  
Cell Death ◽  
Hind Limb ◽  
Muscle Volume ◽  
Chick Embryos ◽  
Relative Contribution ◽  
Hind Limbs ◽  
Lateral Motor Column ◽  
Before And After ◽  
Major Period

Counts were made of the number of motoneurons innervating the hind limbs of 10-day normal and paralysed chick embryos whose right hind limb buds had been subjected to varying degrees of amputation prior to innervation. The number of motoneurons on the intact sides of the paralysed embryos was found to be similar to the number present in normal embryos prior to the major period of motoneuron death. Since it has previously been shown that paralysis does not increase the number of motoneurons generated, this means that normal motoneuron death was largely prevented in the paralysed embryos. There were differences in the distributions of motoneurons in the rostrocaudal axis of the spinal cord between normal and paralysed embryos. Therefore, cell death does not eliminate a uniform fraction of motoneurons throughout the rostrocaudal extent of the chick embryo lumbar lateral motor column. It is also argued that there are differences in the relative contribution of the various lumbosacral levels to different parts of the limb, e.g. the shank, before and after the period of cell death. In both normal and paralysed embryos there was a linear relationship between the volume of limb muscle which developed after amputation and the number of motoneurons surviving in the spinal cord. There was no evidence of a ‘compression’ of motoneurons into the remaining muscle either after amputation alone or after amputation combined with paralysis. Motoneurons are therefore rigidly specified for certain parts of the limb. The relationship between motoneuron number and muscle volume on the amputated side differed from that of the intact side. For a similar increase in muscle volume there was a smaller increase in motoneuron number on the intact sides. This suggested a parallel to the paradoxically small increase in motoneuron number that occurs on the addition of a supernumerary limb.

Changes in serotonin-induced potentials during spinal cord development

1993 ◽  
Vol 69 (4) ◽  
pp. 1338-1349 ◽  
Author(s):  
L. Ziskind-Conhaim ◽  
B. S. Seebach ◽  
B. X. Gao
Keyword(s):  
Spinal Cord ◽  
Direct Action ◽  
Membrane Resistance ◽  
Ventral Horn ◽  
Repetitive Firing ◽  
Lumbar Spinal Cord ◽  
Receptor Subtypes ◽  
Gamma Aminobutyric Acid ◽  
Spinal Neurons ◽  
Lumbar Spinal

1. Motoneuron responses to serotonin (5-hydroxytryptamine, 5-HT), and the growth pattern of 5-HT projections into the ventral horn were studied in the isolated spinal cord of embryonic and neonatal rats. 2. 5-HT projections first appeared in lumbar spinal cord at days 16-17 of gestation (E16-E17) and were localized in the lateral and ventral funiculi. By E18, the projections had grown into the ventral horn, and at 1-2 days after birth they were in close apposition to motoneuron somata. 3. At E16-E17, slow-rising depolarizing potentials of 1-4 mV were recorded intracellularly in lumbar motoneurons in response to bath application of 5-HT. These potentials were not apparent after E18; at that time 5-HT generated long-lasting depolarizations with an average amplitude of 6 mV, and an increase of 11% in membrane resistance. Starting at E18, 5-HT also induced high-frequency fast-rising potentials that were blocked by antagonists of glutamate, gamma-aminobutyric acid, and glycine. 4. Motoneuron responses to 5-HT increased significantly after birth, when 5-HT produced an average depolarization of 19 mV and repetitive firing of action potentials. 5. Tetrodotoxin and high Mg2+ did not reduce the amplitude of the long-lasting depolarizations, which suggested that they were produced by direct action of 5-HT on motoneuron membrane. 6. At all developmental ages, 5-HT reduced the amplitude of dorsal root-evoked potentials. The suppressed responses were neither due to 5-HT-induced depolarization nor the result of a decrease in motoneuron excitability. 7. The pharmacological profile of 5-HT-induced potentials was studied with the use of various agonists and antagonists of 5-HT. The findings indicated that the actions of 5-HT on spinal neurons were mediated via multiple 5-HT receptor subtypes. 8. Our results suggested that 5-HT excited spinal neurons before 5-HT projections grew into the ventral horn. The characteristics of 5-HT-induced potentials changed, however, at the time when the density of 5-HT projections increased in the motor nuclei.

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