Limits...
Interkinetic nuclear migration generates and opposes ventricular-zone crowding: insight into tissue mechanics.

Miyata T, Okamoto M, Shinoda T, Kawaguchi A - Front Cell Neurosci (2015)

Bottom Line: This review will summarize and discuss several topics: the nature of the INM exhibited by neural progenitor cells, the mechanical difficulties associated with INM in the developing cerebral cortex, the community-level mechanisms underlying collective and efficient INM, the impact on overall brain formation when NE/VZ is overcrowded due to loss of INM, and whether and how neural progenitor INM varies among mammalian species.These discussions will be based on recent findings obtained in live, three-dimensional specimens using quantitative and mechanical approaches.A consideration of the physical aspects in the NE/VZ and the mechanical difficulties associated with high-degree pseudostratification (PS) is important for achieving a better understanding of neocortical development and evolution.

View Article: PubMed Central - PubMed

Affiliation: Anatomy and Cell Biology, Nagoya University Graduate School of Medicine Nagoya, Aichi, Japan.

ABSTRACT
The neuroepithelium (NE) or ventricular zone (VZ), from which multiple types of brain cells arise, is pseudostratified. In the NE/VZ, neural progenitor cells are elongated along the apicobasal axis, and their nuclei assume different apicobasal positions. These nuclei move in a cell cycle-dependent manner, i.e., apicalward during G2 phase and basalward during G1 phase, a process called interkinetic nuclear migration (INM). This review will summarize and discuss several topics: the nature of the INM exhibited by neural progenitor cells, the mechanical difficulties associated with INM in the developing cerebral cortex, the community-level mechanisms underlying collective and efficient INM, the impact on overall brain formation when NE/VZ is overcrowded due to loss of INM, and whether and how neural progenitor INM varies among mammalian species. These discussions will be based on recent findings obtained in live, three-dimensional specimens using quantitative and mechanical approaches. Experiments in which overcrowding was induced in mouse neocortical NE/VZ, as well as comparisons of neocortical INM between mice and ferrets, have revealed that the behavior of NE/VZ cells can be affected by cellular densification. A consideration of the physical aspects in the NE/VZ and the mechanical difficulties associated with high-degree pseudostratification (PS) is important for achieving a better understanding of neocortical development and evolution.

No MeSH data available.


Comparison of VZ cells’ spatial conditions between a moderate (7-nucleus-deep) and higher-degree (12-nucleus-deep) pseudostratification. In the 12-nucleus-deep VZ, the short diameter of the nucleus/soma was reduced, and the apical endfeet may be more densified and individually reduced in size.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4309187&req=5

Figure 7: Comparison of VZ cells’ spatial conditions between a moderate (7-nucleus-deep) and higher-degree (12-nucleus-deep) pseudostratification. In the 12-nucleus-deep VZ, the short diameter of the nucleus/soma was reduced, and the apical endfeet may be more densified and individually reduced in size.

Mentions: The observation of Wnt3a-induced thickening and horizontal cellular densification of the VZ provides a good opportunity for further discussion of whether (and, if so, how) the VZ thickening/densification that occurs physiologically during development and evolution might affect VZ cell behaviors. The thickness of the VZ is defined by the extent of PS along the apicobasal axis, i.e., by how many nuclei exhibiting INM are staggered from the apical surface toward the basal side (Sauer, 1935; Smart, 1972). It is likely that as more nuclei are stratified within the VZ, net apicobasal nuclear movements per unit of apical surface area tend to increase. In other words, as the VZ thickens, apicobasal nuclear traffic per unit volume of VZ becomes heavier. Figure 7 compares cell morphology between a VZ with 7-nucleus-deep PS and another with 12-nucleus-deep PS. The comparison is made within a cylinder-like hypothetical column, because time-lapse monitoring of H2B-mCherry-labeled nuclei showed that all nuclei move almost purely apicobasally, rather than horizontally (Okamoto et al., 2013). Probable differences between the two VZ columns with different degrees of PS include reduction in the short diameter of the nucleus/soma (due to the existence of other cells’ processes) and densification of the apical endfeet in the 12-nucleus-deep VZ.


Interkinetic nuclear migration generates and opposes ventricular-zone crowding: insight into tissue mechanics.

Miyata T, Okamoto M, Shinoda T, Kawaguchi A - Front Cell Neurosci (2015)

Comparison of VZ cells’ spatial conditions between a moderate (7-nucleus-deep) and higher-degree (12-nucleus-deep) pseudostratification. In the 12-nucleus-deep VZ, the short diameter of the nucleus/soma was reduced, and the apical endfeet may be more densified and individually reduced in size.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4309187&req=5

Figure 7: Comparison of VZ cells’ spatial conditions between a moderate (7-nucleus-deep) and higher-degree (12-nucleus-deep) pseudostratification. In the 12-nucleus-deep VZ, the short diameter of the nucleus/soma was reduced, and the apical endfeet may be more densified and individually reduced in size.
Mentions: The observation of Wnt3a-induced thickening and horizontal cellular densification of the VZ provides a good opportunity for further discussion of whether (and, if so, how) the VZ thickening/densification that occurs physiologically during development and evolution might affect VZ cell behaviors. The thickness of the VZ is defined by the extent of PS along the apicobasal axis, i.e., by how many nuclei exhibiting INM are staggered from the apical surface toward the basal side (Sauer, 1935; Smart, 1972). It is likely that as more nuclei are stratified within the VZ, net apicobasal nuclear movements per unit of apical surface area tend to increase. In other words, as the VZ thickens, apicobasal nuclear traffic per unit volume of VZ becomes heavier. Figure 7 compares cell morphology between a VZ with 7-nucleus-deep PS and another with 12-nucleus-deep PS. The comparison is made within a cylinder-like hypothetical column, because time-lapse monitoring of H2B-mCherry-labeled nuclei showed that all nuclei move almost purely apicobasally, rather than horizontally (Okamoto et al., 2013). Probable differences between the two VZ columns with different degrees of PS include reduction in the short diameter of the nucleus/soma (due to the existence of other cells’ processes) and densification of the apical endfeet in the 12-nucleus-deep VZ.

Bottom Line: This review will summarize and discuss several topics: the nature of the INM exhibited by neural progenitor cells, the mechanical difficulties associated with INM in the developing cerebral cortex, the community-level mechanisms underlying collective and efficient INM, the impact on overall brain formation when NE/VZ is overcrowded due to loss of INM, and whether and how neural progenitor INM varies among mammalian species.These discussions will be based on recent findings obtained in live, three-dimensional specimens using quantitative and mechanical approaches.A consideration of the physical aspects in the NE/VZ and the mechanical difficulties associated with high-degree pseudostratification (PS) is important for achieving a better understanding of neocortical development and evolution.

View Article: PubMed Central - PubMed

Affiliation: Anatomy and Cell Biology, Nagoya University Graduate School of Medicine Nagoya, Aichi, Japan.

ABSTRACT
The neuroepithelium (NE) or ventricular zone (VZ), from which multiple types of brain cells arise, is pseudostratified. In the NE/VZ, neural progenitor cells are elongated along the apicobasal axis, and their nuclei assume different apicobasal positions. These nuclei move in a cell cycle-dependent manner, i.e., apicalward during G2 phase and basalward during G1 phase, a process called interkinetic nuclear migration (INM). This review will summarize and discuss several topics: the nature of the INM exhibited by neural progenitor cells, the mechanical difficulties associated with INM in the developing cerebral cortex, the community-level mechanisms underlying collective and efficient INM, the impact on overall brain formation when NE/VZ is overcrowded due to loss of INM, and whether and how neural progenitor INM varies among mammalian species. These discussions will be based on recent findings obtained in live, three-dimensional specimens using quantitative and mechanical approaches. Experiments in which overcrowding was induced in mouse neocortical NE/VZ, as well as comparisons of neocortical INM between mice and ferrets, have revealed that the behavior of NE/VZ cells can be affected by cellular densification. A consideration of the physical aspects in the NE/VZ and the mechanical difficulties associated with high-degree pseudostratification (PS) is important for achieving a better understanding of neocortical development and evolution.

No MeSH data available.