Axons in the Chick Embryo Follow Soft Pathways Through Developing Somite Segments.

During patterning of the peripheral nervous system, motor axons grow sequentially out of the neural tube in a segmented fashion to ensure functional integration of the motor roots between the surrounding cartilage and bones of the developing vertebrae. This segmented outgrowth is regulated by the intrinsic properties of each segment (somite) adjacent to the neural tube, and in particular by chemical repulsive guidance cues expressed in the posterior half. Yet, knockout models for such repulsive cues still display initial segmentation of outgrowing motor axons, suggesting the existence of additional, yet unknown regulatory mechanisms of axon growth segmentation.

Author Correction: Niche stiffness underlies the ageing of central nervous system progenitor cells.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Niche stiffness underlies the ageing of central nervous system progenitor cells.

Ageing causes a decline in tissue regeneration owing to a loss of function of adult stem cell and progenitor cell populations. One example is the deterioration of the regenerative capacity of the widespread and abundant population of central nervous system (CNS) multipotent stem cells known as oligodendrocyte progenitor cells (OPCs). A relatively overlooked potential source of this loss of function is the stem cell 'niche'-a set of cell-extrinsic cues that include chemical and mechanical signals.

Effect of vital dyes on human corneal endothelium and elasticity of Descemet's membrane.

The purpose of this study was to evaluate the effects of vital dyes on human Descemet's membranes (DMs) and endothelia. DMs of 25 human cadaveric corneas with research consent were treated with dyes routinely used in Descemet membrane endothelial keratoplasty (DMEK), 0.05% Trypan blue (TB) or a combination of 0.

The role of cell body density in ruminant retina mechanics assessed by atomic force and Brillouin microscopy.

Cells in the central nervous system (CNS) respond to the stiffness of their environment. CNS tissue is mechanically highly heterogeneous, thus providing motile cells with region-specific mechanical signals. While CNS mechanics has been measured with a variety of techniques, reported values of tissue stiffness vary greatly, and the morphological structures underlying spatial changes in tissue stiffness remain poorly understood.

The soft mechanical signature of glial scars in the central nervous system.

Injury to the central nervous system (CNS) alters the molecular and cellular composition of neural tissue and leads to glial scarring, which inhibits the regrowth of damaged axons. Mammalian glial scars supposedly form a chemical and mechanical barrier to neuronal regeneration. While tremendous effort has been devoted to identifying molecular characteristics of the scar, very little is known about its mechanical properties.

Interkinetic nuclear migration is centrosome independent and ensures apical cell division to maintain tissue integrity.

Pseudostratified epithelia are widespread during animal development and feature elongated cells whose nuclei adopt various positions along the apicobasal cell axis. Before mitosis, nuclei migrate toward the apical surface, and subsequent divisions occur apically. So far, the exact purpose of this nuclear migration remained elusive.

Mitotic position and morphology of committed precursor cells in the zebrafish retina adapt to architectural changes upon tissue maturation.

The development of complex neuronal tissues like the vertebrate retina requires the tight orchestration of cell proliferation and differentiation. Although the complexity of transcription factors and signaling pathways involved in retinogenesis has been studied extensively, the influence of tissue maturation itself has not yet been systematically explored. Here, we present a quantitative analysis of mitotic events during zebrafish retinogenesis that reveals three types of committed neuronal precursors in addition to the previously known apical progenitors.

Ectopic expression of single transcription factors directs differentiation of a medaka spermatogonial cell line.

The capability to form all cell types of the body is a unique feature of stem cells. However, many questions remain concerning the mechanisms regulating differentiation potential. The derivation of spermatogonial cell lines (SGs) from mouse and human, which can differentiate across germ-layer borders, suggested male germ cells as a potential stem cell source in addition to embryonic stem cells.