The Special Senses

Khong, T. Yee

doi:10.1007/978-3-319-19207-9_33

Cited by 2 publications

(2 citation statements)

References 72 publications

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“…Later, the cells in the LV wall elongate and fill the lumen to create the lens (Cvekl and Ashery-Padan, 2014). Malformations of the lens can cause birth defects such as congenital cataracts (opaque lens), microphakia (small lens), ectopia lentis (abnormal lens position), and aphakia (absence of the lens) (Khong, 2015).…”

Section: Introductionmentioning

confidence: 99%

Apoptosis generates mechanical forces that close the lens vesicle in the chick embryo

Oltean

Taber

2018

Phys. Biol.

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During the initial stages of eye development, optic vesicles grow laterally outward from both sides of the forebrain and come into contact with the surrounding surface ectoderm (SE). Within the region of contact, these layers then thicken locally to create placodes and invaginate to form the optic cup (primitive retina) and lens vesicle (LV), respectively. This paper examines the biophysical mechanisms involved in LV formation, which consists of three phases: (1) lens placode formation; (2) invagination to create the lens pit (LP); and (3) closure to form a complete ellipsoidally shaped LV. Previous studies have suggested that extracellular matrix deposited between the SE and optic vesicle causes the lens placode to form by locally constraining expansion of the SE as it grows, while actomyosin contraction causes this structure to invaginate. Here, using computational modeling and experiments on chick embryos, we confirm that these mechanisms for Phases 1 and 2 are physically plausible. Our results also suggest, however, that they are not sufficient to close the LP during Phase 3. We postulate that apoptosis provides an additional mechanism by removing cells near the LP opening, thereby decreasing its circumference and generating tension that closes the LP. This hypothesis is supported by staining that shows a ring of cell death located around the LP opening during closure. Inhibiting apoptosis in cultured embryos using caspase inhibitors significantly reduced LP closure, and results from a finite-element model indicate that closure driven by cell death is plausible. Taken together, our results suggest an important mechanical role for apoptosis in lens development.

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Section: Introductionmentioning

confidence: 99%

Apoptosis generates mechanical forces that close the lens vesicle in the chick embryo

Oltean

Taber

2018

Phys. Biol.

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“…Even relatively minor abnormalities can have major effects on vision. Developmental malformations also can lead to ocular defects including coloboma (missing part of eye, possibly caused by failure of the optic fissure to close), microphthalmia (abnormally small eye), congenital cataracts (opaque lens), microphakia (small lens), ectopia lentis (abnormal lens position), aniridia (absence of the iris), and aphakia (absence of the lens) (Mic et al 2004, Khong 2015). Fully understanding the causes of these defects requires knowing how the eye is constructed.…”

Section: Discussionmentioning

confidence: 99%

How mechanical forces shape the developing eye

Hosseini

Taber

2018

Progress in Biophysics and Molecular Biology

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In the vertebrate embryo, the eyes develop from optic vesicles that grow laterally outward from the brain tube and contact the overlying surface ectoderm. Within the region of contact, each optic vesicle and the surface ectoderm thicken to form placodes, which then invaginate to create the optic cup and lens pit, respectively. Eventually, the optic cup becomes the retina, while the lens pit closes to form the lens vesicle. Here, we review current hypotheses for the physical mechanisms that create these structures and present novel three-dimensional computer (finite-element) models to illustrate the plausibility and limitations of these hypotheses. Taken together, experimental and numerical results suggest that the driving forces for early eye morphogenesis are generated mainly by differential growth, actomyosin contraction, and regional apoptosis, with morphology mediated by physical constraints provided by adjacent tissues and extracellular matrix. While these studies offer new insight into the mechanics of eye development, future work is needed to better understand how these mechanisms are regulated to precisely control the shape of the eye.

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The Special Senses

Cited by 2 publications

References 72 publications

Apoptosis generates mechanical forces that close the lens vesicle in the chick embryo

Apoptosis generates mechanical forces that close the lens vesicle in the chick embryo

How mechanical forces shape the developing eye

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