Early lens development in the zebrafish: A three‐dimensional time‐lapse analysis

Abstract

In vivo, high-resolution, time-lapse imaging characterized lens development in the zebrafish from 16 to 96 hr postfertilization (hpf). In zebrafish, the lens placode appeared in the head ectoderm, similar to mammals. Delamination of the surface ectoderm resulted in the formation of the lens mass, which progressed to a solid sphere of cells separating from the developing cornea at approximately 24 hpf. A lens vesicle was not observed and apoptosis was not a major factor in separation of the lens from the future cornea. Differentiation of primary fibers began in the lens mass followed by formation of the anterior epithelium after delamination was complete. Secondary fibers differentiated from elongating epithelial cells near the posterior pole. Quantification characterized three stages of lens growth. The study confirmed the advantages of live-cell imaging for three-dimensional quantitative structural characterization of the mechanism(s) responsible for cell differentiation in formation of a transparent, symmetric, and refractile lens.

The myosin chaperone UNC45B is involved in lens development and autosomal dominant juvenile cataract

“…16 In zebrafish, mutations that produce ocular disorders, including cataracts, are found in a similar spectrum of candidate genes as we have seen in humans, suggesting that eye development processes in the two systems are fundamentally similar at the cellular level despite differences in timing and morphology during development. 4,17,41,42 In conclusion, we have characterized a human UNC45B mutation in a Danish family with autosomal dominant cataract developing in early childhood. Experimental data using a zebrafish unc45b mutant show an eye developmental phenotype.…”

“…Differentiation of lens fiber cells begins in the zebrafish at B24 h post fertilization (hpf) and involves processes including cellular reorganization and organelle degeneration that result in a transparent lens and functional visual system by 72 hpf. 17,18 Disassembly of actin stress fibers is believed to induce lens cell differentiation and lead to the formation of cortical fibers through the reorganization of actin filaments. 18,19 Zebrafish embryonic eyes were examined for lens fiber cell boundaries, differentiation, and nuclear retention.…”

The lens: a classical model of embryonic induction providing new insights into cell determination in early development

“…Subsequently, the lens pit deepens and the connection with the overlying surface ectoderm, the prospective cornea, is abolished resulting in the formation of the lens vesicle (figure 1d ). In lower vertebrates, such as fish and frog, lens formation proceeds via delamination of the lens placodal cells [4,5]. After formation of the lens vesicle, cells at the centre of the posterior side of the lens will elongate and differentiate into primary lens fibre cells, whereas cells of the lens epithelium at the anterior side of the lens retain their ability to proliferate and will generate fibre cells throughout life (figure 1e) [3].…”

The ubiquitin proteasome system is required for cell proliferation of the lens epithelium and for differentiation of lens fiber cells in zebrafish

“…In the lens vesicle, posterior epithelial cells differentiate into lens fiber cells, whereas anterior epithelial cells are retained as proliferative lens progenitor cells (Bassnett et al, 1999;Lovicu and McAvoy, 2005). In zebrafish, a lens mass without a vesicle delaminates, and the cells reorganize into the central core and epithelial cells (Greiling and Clark, 2009). At the interface between the anterior lens epithelium and posterior lens fiber core, called the equator, epithelial cells differentiate into lens fiber cells, which elongate towards both anterior and posterior poles of the lens sphere and cover the old lens fiber core.…”