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Methods (San Diego, Calif.) Jun 2014The eye has been one of the most intensively studied organs in Drosophila. The wealth of knowledge about its development, as well as the reagents that have been... (Review)
Review
The eye has been one of the most intensively studied organs in Drosophila. The wealth of knowledge about its development, as well as the reagents that have been developed, and the fact that the eye is dispensable for survival, also make the eye suitable for genetic interaction studies and genetic screens. This article provides a brief overview of the methods developed to image and probe eye development at multiple developmental stages, including live imaging, immunostaining of fixed tissues, in situ hybridizations, and scanning electron microscopy and color photography of adult eyes. Also summarized are genetic approaches that can be performed in the eye, including mosaic analysis and conditional mutation, gene misexpression and knockdown, and forward genetic and modifier screens.
Topics: Animals; Developmental Biology; Drosophila; Eye; Gene Expression Regulation, Developmental; Humans; In Situ Hybridization; Microscopy, Electron, Scanning; Mutation
PubMed: 24784530
DOI: 10.1016/j.ymeth.2014.04.007 -
Current Topics in Developmental Biology 2019This chapter provides an overview of the early developmental origins of six ocular tissues: the cornea, lens, ciliary body, iris, neural retina, and retina pigment... (Review)
Review
This chapter provides an overview of the early developmental origins of six ocular tissues: the cornea, lens, ciliary body, iris, neural retina, and retina pigment epithelium. Many of these tissue types are concurrently specified and undergo a complex set of morphogenetic movements that facilitate their structural interconnection. Within the context of vertebrate eye organogenesis, we also discuss the genetic hierarchies of transcription factors and signaling pathways that regulate growth, patterning, cell type specification and differentiation.
Topics: Animals; Ciliary Body; Cornea; Eye; Gene Expression Regulation, Developmental; Humans; Lens, Crystalline; Organogenesis; Retina; Transcription Factors
PubMed: 30797514
DOI: 10.1016/bs.ctdb.2018.12.008 -
Current Topics in Developmental Biology 2010The vertebrate eye comprises tissues from different embryonic origins: the lens and the cornea are derived from the surface ectoderm, but the retina and the epithelial...
The vertebrate eye comprises tissues from different embryonic origins: the lens and the cornea are derived from the surface ectoderm, but the retina and the epithelial layers of the iris and ciliary body are from the anterior neural plate. The timely action of transcription factors and inductive signals ensure the correct development of the different eye components. Establishing the genetic basis of eye defects in zebrafishes, mouse, and human has been an important tool for the detailed analysis of this complex process. A single eye field forms centrally within the anterior neural plate during gastrulation; it is characterized on the molecular level by the expression of "eye-field transcription factors." The single eye field is separated into two, forming the optic vesicle and later (under influence of the lens placode) the optic cup. The lens develops from the lens placode (surface ectoderm) under influence of the underlying optic vesicle. Pax6 acts in this phase as master control gene, and genes encoding cytoskeletal proteins, structural proteins, or membrane proteins become activated. The cornea forms from the surface ectoderm, and cells from the periocular mesenchyme migrate into the cornea giving rise for the future cornea stroma. Similarly, the iris and ciliary body form from the optic cup. The outer layer of the optic cup becomes the retinal pigmented epithelium, and the main part of the inner layer of the optic cup forms later the neural retina with six different types of cells including the photoreceptors. The retinal ganglion cells grow toward the optic stalk forming the optic nerve. This review describes the major molecular players and cellular processes during eye development as they are known from frogs, zebrafish, chick, and mice-showing also differences among species and missing links for future research. The relevance to human disorders is one of the major aspects covered throughout the review.
Topics: Animals; Bone Morphogenetic Proteins; Eye; Gene Expression Regulation, Developmental; Homeodomain Proteins; Humans; Morphogenesis; Mutation; Signal Transduction; Transcription Factors; Visual Fields; Wnt Proteins
PubMed: 20691855
DOI: 10.1016/S0070-2153(10)90010-0 -
Annual Review of Cell and Developmental... 2001This review provides a synthesis that combines data from classical experimentation and recent advances in our understanding of early eye development. Emphasis is placed... (Review)
Review
This review provides a synthesis that combines data from classical experimentation and recent advances in our understanding of early eye development. Emphasis is placed on the events that underlie and direct neural retina formation and lens induction. Understanding these events represents a longstanding problem in developmental biology. Early interest can be attributed to the curiosity generated by the relatively frequent occurrence of disorders such as cyclopia and anophthalmia, in which dramatic changes in eye development are readily observed. However, it was the advent of experimental embryology at the turn of the century that transformed curiosity into active investigation. Pioneered by investigators such as Spemann and Adelmann, these embryological manipulations have left a profound legacy. Questions about early eye development first addressed using tissue manipulations remain topical as we try to understand the molecular basis of this process.
Topics: Animals; Body Patterning; Drosophila; Embryonic Induction; Eye; Gene Expression Regulation, Developmental; Lens, Crystalline; Nervous System; Optic Disk; Retina; Vertebrates
PubMed: 11687490
DOI: 10.1146/annurev.cellbio.17.1.255 -
Mechanisms of Development Aug 1998Development of the eye can be subdivided into three phases. The first phase is the formation of the major structures of the eye by the processes of induction and... (Review)
Review
Development of the eye can be subdivided into three phases. The first phase is the formation of the major structures of the eye by the processes of induction and regional specification. The second is the maturation of these structures to form the functional eye, and the third phase is the formation of neuronal connections between retina and the optic tectum. These processes are tightly regulated by signalling cascades that direct axonal outgrowth, cellular proliferation and differentiation. Some members of these signalling cascades have been identified in recent studies. These include secreted factors which transmit signals extracellularly, and receptors and transcription factors which are members of intracellular signalling pathways that respond to extracellular signals. This review summarizes the recent research that has implicated these factors in playing a role in eye development on the basis of functional or expression criteria.
Topics: Animals; Embryonic Induction; Eye; Gene Expression Regulation, Developmental; Lens, Crystalline; Optic Disk; Pigment Epithelium of Eye; Retina; Retinal Ganglion Cells; Vertebrates
PubMed: 9767078
DOI: 10.1016/s0925-4773(98)00117-8 -
Progress in Retinal and Eye Research Jan 2018The development of the ocular vasculatures is perfectly synchronized to provide the nutritional and oxygen requirements of the forming human eye. The fetal vasculature... (Review)
Review
The development of the ocular vasculatures is perfectly synchronized to provide the nutritional and oxygen requirements of the forming human eye. The fetal vasculature of vitreous, which includes the hyaloid vasculature, vasa hyaloidea propria, and tunica vasculosa lentis, initially develops around 4-6 weeks gestation (WG) by hemo-vasculogenesis (development of blood and blood vessels from a common progenitor, the hemangioblast). This transient fetal vasculature expands around 12 WG by angiogenesis (budding from primordial vessels) and remains until a retinal vasculature begins to form. The fetal vasculature then regresses by apoptosis with the assistance of macrophages/hyalocytes. The human choroidal vasculature also forms by a similar process and will supply nutrients and oxygen to outer retina. This lobular vasculature develops in a dense collagenous tissue juxtaposed with a cell constitutively producing vascular endothelial growth factor (VEGF), the retinal pigment epithelium. This epithelial/endothelial relationship is critical in maintaining the function of this vasculature throughout life and maintaining it's fenestrated state. The lobular capillary system (choriocapillaris) develops first by hemo-vasculogenesis and then the intermediate choroidal blood vessels form by angiogenesis, budding from the choriocapillaris. The human retinal vasculature is the last to develop. It develops by vasculogenesis, assembly of CXCR4/CD39 angioblasts or vascular progenitors perhaps using Muller cell Notch1 or axonal neuropilinin-1 for guidance of semaphorin 3A-expressing angioblasts. The fovea never develops a retinal vasculature, which is probably due to the foveal avascular zone area of retina expressing high levels of antiangiogenic factors. From these studies, it is apparent that development of the mouse ocular vasculatures is not representative of the development of the human fetal, choroidal and retinal vasculatures.
Topics: Choroid; Humans; Neovascularization, Pathologic; Retina; Retinal Pigment Epithelium; Retinal Vessels; Vascular Endothelial Growth Factor A; Vitreous Body
PubMed: 29081352
DOI: 10.1016/j.preteyeres.2017.10.001 -
Trends in Neurosciences Sep 1997Several genes involved in the regulation of eye development in different species have been identified. Structural and functional conservation have been found between... (Review)
Review
Several genes involved in the regulation of eye development in different species have been identified. Structural and functional conservation have been found between some of these genes in organisms as diverse as Drosophila and mouse. One notable example is the relationship between the mouse Pax6 gene and eyeless of Drosophila. Ectopic expression of eyeless or mouse Pax6 in Drosophila results in the formation of additional eyes. Recently, another homeobox gene, Six3, was found to promote ectopic lens formation in fish embryos. The next step will be to unravel the associated regulatory pathways of these genes and assess the degree to which they display evolutionary conservation. This will be important in order to assimilate these findings with current anatomical and embryological models. It seems reasonable to believe that in the near future the characterization of the whole framework required for vertebrate eye development will be accomplished.
Topics: Animals; Drosophila; Eye; Fishes; Humans; Mice
PubMed: 9292971
DOI: 10.1016/s0166-2236(97)01082-5 -
Experimental Eye Research Jul 2008Research with young mammals and chicks has shown that the visual environment can affect the refractive development of the eye by enhancing or slowing axial eye growth,... (Review)
Review
Research with young mammals and chicks has shown that the visual environment can affect the refractive development of the eye by enhancing or slowing axial eye growth, but the effect on the refractive components of the eye, the lens and cornea, are less clear. A review of the literature indicates that the lens is minimally affected, if at all, and results vary depending on whether the lens is studied in an isolated state or with the accommodative apparatus intact. Research has shown that the development of myopia or hyperopia in young chicks alters lens focal length and magnitude of the accommodative response. However, the result may be indirect or passive due to the effect of the change in size and shape of the globe on the articulation between the ciliary body and lens. Recent research has also investigated the role of the lens in induced refractive error development in a fish, tilapia (Oreochromis niloticus). Translucent goggles were sutured over one eye for 4 weeks to induce form deprivation myopia while the untreated eye served as an untreated contralateral control. In addition to measuring refractive state and intraocular dimensions, a scanning laser system was used to determine the optical quality of excised lenses. All the deprived fish eyes developed significant amounts of myopia and the vitreous and anterior chambers of the treated eye were significantly longer axially than those of the untreated contralateral eyes. No significant change in optical quality was found between lenses of the myopic and non-myopic eyes and the fish recovered completely from the myopia five days after the goggle was removed. The results show that although fish, unlike higher vertebrates, are capable of lifelong growth, the visual environment is an important factor controlling ocular development in this group as well, and eye development is not strictly genetically determined. This review indicates that lens growth and optical development is independent from the refractive development of the whole eye.
Topics: Accommodation, Ocular; Animals; Birds; Disease Models, Animal; Eye; Fishes; Lens, Crystalline; Mammals; Refraction, Ocular; Refractive Errors; Sensory Deprivation
PubMed: 18405895
DOI: 10.1016/j.exer.2008.03.001 -
Frontiers in Bioscience : a Journal and... Sep 2006The canonical Wnt/Fzd signaling pathway is highly conserved among various species. Increasing evidence is accumulating for non-canonical Wnt signaling pathways,... (Review)
Review
The canonical Wnt/Fzd signaling pathway is highly conserved among various species. Increasing evidence is accumulating for non-canonical Wnt signaling pathways, analogous to those discovered in Drosophila, being operative in vertebrates. Similarly, the networks of genes involved in eye development show significant conservation during evolution. The amenability of Drosophila for genetic manipulation and analysis of ocular phenotypes has delivered a great deal of information about the roles of the Wnt/Fzd signaling pathways at various stages of ocular development and growth, particularly in regulating the formation and size of the eye field, cell proliferation, polarity and differentiation. In addition to the numerous recent studies that have identified the expression of various components of these signaling pathways in the developing vertebrate eye, functional studies have revealed significant parallels in the way that Wnt/Fz signals regulate the formation of the vertebrate eye field and also the proliferation and differentiation of cells, particularly in the lens and retina. Significant advances have also recently been made in identifying mutations in these signaling pathways that underlie or contribute to various ocular diseases such as exudative vitreoretinopathy, retinal degenerations, cataract, ocular tumors and various congenital ocular malformations. Combined with the mechanistic studies in vertebrate and invertebrate models, these studies point to important functional roles for Wnt/Fzd pathways in the human eye. Further investigation of how these pathways function during eye development and growth may yield important insights into novel therapeutic approaches to treat or prevent diseases that cause blindness.
Topics: Animals; Drosophila Proteins; Drosophila melanogaster; Eye; Eye Diseases; Frizzled Receptors; Gene Expression Regulation, Developmental; Lens, Crystalline; Proto-Oncogene Proteins; Retina; Signal Transduction; Vertebrates; Wnt Proteins; Wnt1 Protein
PubMed: 16720326
DOI: 10.2741/1982 -
Ophthalmic Research 2004In recent years, the zebrafish has become a favourite model organism for biologists studying developmental processes in vertebrates. Its rapid embryonic development, the... (Review)
Review
In recent years, the zebrafish has become a favourite model organism for biologists studying developmental processes in vertebrates. Its rapid embryonic development, the transparency of its embryos, the large number of offspring together with several other advantages make it ideal for discovering and understanding the genes that regulate embryonic development as well as the physiology of the adult organism. Zebrafish are very visually orientated, and their retina and lens show much the same morphology as other vertebrates including humans. For this reason, they are well suited for examining ocular development, function and disease. This review describes the advantages of the zebrafish as a model organism as well as giving an overview of eye development in this species. It has a particular focus on morphological as well as molecular aspects of the development of the lens.
Topics: Animals; Eye; Lens, Crystalline; Models, Animal; Retina; Transcription Factors; Zebrafish
PubMed: 15007235
DOI: 10.1159/000076105