The pax6 gene locus is a transcription factor for the various genes and growth factors involved in eye formation. Vertebrate optx2 appears to be important in eye development, as human chromosomal deletions of the optx2containing region lead to bilateral anophthalmia. Development of the vertebrate eye developmental biology ncbi. An individual gains knowledge of its environment through its sensory organs. Comparative anatomy is to make a comparative study of the anatomy of an organ in different groups of vertebrates and try to derive the evolutionary significance from it, and to understand as to why an organ evolved the way it is present now. Specification of the vertebrate eye by a network of eye field transcription factors. To date little is known about the nature and interaction of the genes controlling these steps. Pdf vertebrate eye development as modeled in drosophila. Development of the vertebrate eye requires a series of steps including specification of the anterior neural plate, evagination of the optic vesicles from the ventral forebrain, and the cellular. Vertebrate eye development is a dynamic process that couples morphogenesis, migration of extraocular periocular mesenchyme pom cells to the eye, and retinal patterning along the nasotemporal and dorsoventral dv axes. New perspectives on eye development and the evolution of. The study of the development of the vertebrate retina appeared to us to have reached such a point of synthesis. Isolation of a drosophila homolog of the vertebrate homeobox.
In contrast, the fact that all eyes use members of the opsin protein family and that common molecules are used during development in many eye. Cells from both the mesodermal and the ectodermal tissues contribute to the formation of the eye. As in drosophila pax6 acts a master control gene for eye development. Illustration of a transverse section of the vertebrate eye, showing the principal eye tissues and their arrangement within the eyeball. Copp neural development unit, ucl institute of child health, london, uk the developmental process of neurulation involves a series of coordinated morphological events, which result. Eye development in vertebrates and drosophila the compound eyes of insects have a radically different structure to that of the more familiar type of eye found in vertebrates. Vertebrate eye development as modeled in drosophila. Through a groove the choroid fissure, the hyaloid artery later the central artery of the retina enters the eye.
Within the last decade of the 20th century, a return to some of the old questions with the new approaches has put eye development back into the limelight. The vertebrate retina has been widely used as a model to study the development of the central nervous system. Eye formation in the human embryo begins at approximately three weeks into embryonic development and continues through the tenth week. The vertebrate eye comprises tissues from different embryonic origins. Nov 30, 2016 the vertebrate eye is a highly specialized sensory organ, which is derived from the anterior neural plate, head surface ectoderm, and neural crestderived mesenchyme. Invertebrate and vertebrate eye development sciencedirect. With the broad spectral range of daylight, four spectral classes of cone. Four muscles innervated by the third cranial nerve were derived from the first muscle block, with one muscle developed from the second, and another from the third muscle block, these being innervated by the fourth and sixth cranial nerves respectively. Genetic aspects of embryonic eye development in vertebrates. Illustrationofatransverse sectionofthe vertebrate eye, showing the principal eye tissues and their arrangement within the eyeball. The major cellular events, such as dedifferentiation and transdifferentiation, which allow complex organ and body part regeneration, are discussed. Vertebrate eye development is initiated at the end of gastrulation with the determination of the retina anlage in the anterior neuroectoderm.
Invertebrate and vertebrate eye development, volume 93 1st. Vertebrate eye development as modeled in drosophila human. Vertebrate eye development is a complex phenomenon that requires a precise series of morphogenetic and differentiation events. Although it is commonly depicted as a series of epithelial sheet folding events, this does not represent an empirically supported model. Vertebrate eye development is initiated early in embryogenesis during lategastrulation when the ectoderm is divided into four domains. New perspectives on eye development and the evolution of eyes and photoreceptors. The major sensory organs of the head develop from the interactions of the neural tube with a series of epidermal thickenings called the cranial ectodermal placodes. Mathers5 and milan jamrich,1,2 1program in developmental biology, baylor college of medicine, houston, tx, usa, 2departments of molecular and human genetics and molecular and cellular biology, baylor college of medicine, houston, tx, usa, 3division of molecular and human. Evolution of the vertebrate eye oxford scholarship. Comparison of vertebrate and insect eye development. Vertebrate eye development accessscience from mcgrawhill. Understanding these events represents a longstanding problem in developmental biology. Among these the pax6 genes play a major role in the genetic control of eye development. Aberrant patterning during ocular development often results in defects.
Early evolution of the vertebrate eyefossil evidence gavin c. Fields of investigation have a natural evolution, rdoving through periods of initial excitement, of framing of questions and controversy, to periods of synthesis and restatement of questions. Phenotypic convergence of the geometry of cephalopod and most vertebrate eyes creates the impression that the vertebrate eye evolved from an imaging cephalopod eye, but this is not the case, as the reversed roles of their respective ciliary and rhabdomeric. From these, the development of the standard pattern of vertebrate eye muscles was worked out. Eye development has therefore long been a favorite for exploring mechanisms of cell fate choice, patterning and cell signaling. Development of the vertebrate central nervous system. Mutations in pax6 genes affect eye development in humans, mice, and drosophila, and misexpression of pax6 genes in drosophila can induce. The information carried by light has led to the evolution of light detection and ultimately, eyes in living organisms. Here, we combine fourdimensional imaging with custom cell tracking software and photoactivatable fluorophore labeling to determine the cellular dynamics underlying. For accounts of the origin and interrelationship of eyes in different phyla, see refs 610. A the optic vesicle evaginates from the brain and contacts the overlying ectoderm, inducing a lens placode. We also describe the important clues to the evolutionary origin of the vertebrate eye that can be found by studying the embryological development of our own eye, by examining the molecular genetic.
Many researchers have found the evolution of the eye attractive to study, because the eye distinctively exemplifies an analogous organ found in many animal forms. In the first phase, the process of induction via localized signaling leads to the regional specification and formation of the major morphological structures of the eye. Development of the eye can be subdivided into three phases. Unlike drosophila the vertebrate eye is not entirely epidermal in origin. Subsequently, the surface ectoderm, in conjunction with the. Development of the vertebrate eye an individual gains knowledge of its environment through its sensory organs. This chapter provides an overview of retinal development, and includes a summary of the process of eye organogenesis, a discussion of major principles of retinal neurogenesis, and describes some of the key molecular factors critical for retinal development. The lens, which is part of the anterior segment of the eye, consists of the lens epithelium and lens fibers, which make up the bulk of the lens mass. Investigating the role of bmp antagonists in vertebrate. Molecular regulators involved in vertebrate eye development. Light from the sun carries energy and information and both are essential for life on earth. Development of the vertebrate eye and retina sciencedirect. Development of the vertebrate retina perspectives in vision.
Development of the vertebrate eye see also figure 6. Eye development is initiated by the master control gene pax6, a homeobox gene with known homologues in humans aniridia, mice small eye, and drosophila eyeless. Development of astrocytes in the vertebrate eye request pdf. The degree of regeneration, however, varies considerably among tissues within a body and among species, with urodeles being the most spectacular. All eyed animals share much of the genetic machinery for eye development.
Pdf molecular regulators involved in vertebrate eye. Its accessibility and relatively simple organization allow analysis of basic mechanisms such as cell proliferation, differentiation and death. The mature, functional, and healthy eye is generated by the coordinated regulatory interaction of numerous and diverse developing tissues. Conclusion the eyes begin to develop as a pair of outpocketings on each side of the forebrain at day 22. Developmental origin of vertebrate rpe cells the vertebrate eye develops from an evagination of the neuroepithelium in the region of the ventral forebrain. Specification of the vertebrate eye by a network of eye. Review the chicken limb embryology, genetics and teratology the chick embryo has a long history in investigations of vertebrate limb development because of the ease with which its limbs can be experimentally manipulated. The vertebrate eye is an extraordinary organ specifically, a photoreceptive sense organ in terms of its structure, function, and development. This book provides an uptodate and comprehensive overview of the field. Early evolution of the vertebrate eyefossil evidence. During embryonic development the establishment and maintenance of appropriate relationships among the several ocular tissues remit from an orderly complex of. Gruss and coworkers have proposed that vertebrate eye development can be empirically divided into three phases. Regulation of vertebrate eye development by rx genes. The mature vertebrate retina, with its stereotypical laminar and mosaic organizations, is derived from an apparently uniform, singlelayered retinal neuroepithelium during development.
You can correct me wherever i am wrong and this was a power point presentation. The cellular and molecular mechanisms of vertebrate lens. Our understanding of the process and molecular mechanisms that result in the generation, differentiation, patterning, and subsequent wiring of numerous neuronal. Astrocytes represent the earliest glial population in the embryonic optic nerve, contributing critically to retinal angiogenesis and. Development of the vertebrate eye developmental biology. A large number of signaling molecules and transcription factors that control key events underlying this process have been identified jean et al.
We here intend to highlight recent insights into their developmental speci. The formation of a functional vertebrate eye involves the precisely coordinated development of the anterior neur. We then endeavour to integrate these findings to develop a plausible and coherent sequence for vertebrate eye evolution. Comparative anatomy zoology for ias, ifos and other. Throughout evolution, particular genes have become associated with distinct aspects of eye development, and these suites of genes have. If hagfish is basil to chordates, opportunity to see the earliest examples of vertebrate. We also describe the important clues to the evolutionary origin of the vertebrate eye that can be found by studying the embryological development of our own eye, by examining the molecular genetic record preserved in our own genes and in the genes of other vertebrates, and through consideration of the imperfections or evolutionary scars. Normal development of the eye requires a rather complex interplay between different tissues of the eye and involves several reciprocal inductive events fig. Evolution of vision and its relationship to ocular development evo. The pax6 gene product, a transcription factor, is a key player in the process. The vertebrate camera eye with a lens, a variable pupil aperture, and a photosensitive receptor layer in the retina, evolved in primitive jawless fish under relatively bright light in shallow seas. Nguyen, susan skuntz, stefano bertuzzi and heinz arnheiter. So far few genes have been identified that, when overexpressed, can initiate ectopic eye formation.
The cellular and molecular mechanisms of vertebrate lens development ales cvekl1,2, and ruth asherypadan3. Molecular regulators involved in vertebrate eye development dominique jean, kenneth ewan, peter gruss department of molecular cell biology, max planck institute of biophysical chemistry, am fassberg, 37 077 go. Several key transcription factors, including lhx2, otx2, pax6, rax, six3, six6 and sox2, among others, are involved in early stages of vertebrate eye development, in the specification of an eye field in the anterior neural plate. The optic vesicles contact the surface ectoderm and induce lens formation. A window to the earliest development of the vertebrate eye hagfish. Whether the eye evolved once or many times depends on the definition of an eye. Vision is acquired during embryonic development as a result of the coordinated formation and growth of several different eye tissues. Eye development and retinogenesis whitney heavner and larysa pevny uncneurosciencecenter, department of genetics,universityofnorthcarolina,chapelhill, northcarolina27599 correspondence. University of virginia, charlottesville, virginia, usa grainger vertebrate eye determination is mediated by a series of inductive interactions that have now been more precisely defined with the use of regional markers. The first phase is the formation of the major structures of the eye by the processes of induction and regional specification. Invertebrate and vertebrate eye development, volume 93.
Eye development downloadable powerpoint presentation. The establishment of retinal identity and the subsequent patterning of the optic vesicle are the key steps in early vertebrate eye development. The central role for pax6 in eye development is conserved throughout the animal kingdom as the murine pax6 gene induces ectopic eyes in transgenic drosophila despite the obvious diverse organization of the eye in the fruit fly compared to vertebrates. Experimental embryology of the vertebrate eye iovs.
In many animals, the embryo soon develops into a free living larval form. Here we concentrate on the origin of the vertebrate eye. The compound eyes of insects have a radically different structure to that of the more familiar type of eye found in. Zuber me1, gestri g, viczian as, barsacchi g, harris wa. Regulation of vertebrate eye development by rx genes travis j. Of note is six3, which is expressed exclusively in the. The neural retina of the eye must undergo the neurogenesis of multiple retinal cell types in the correct ratios and spatial patterns. The evolution of the vertebrate eye has long served as one of the most intriguing problems of modern evolutionary and developmental biology. This chapter describes the evolution of vertebrate camera eyes and concentrates on color vision and visual pigments. Emphasis is placed on the events that underlie and direct neural retina formation and lens induction. Simple light detection is found in bacteria, singlecelled organisms, plants and animals.
Abstract vertebrate and invertebrate eye development require the activity of several evolutionarily conserved genes. The single central eye field, generated from the anterior neural plate, divides to give rise to the optic vesicle, which evaginates toward the head surface ectoderm. However both types of eye have common elements, including lenses, photoreceptors and pigmented cells. At metamorphosis, the lamprey eye grows considerably in size, the retina differentiates fully, the lens develops, the cornea splits into scleral and dermal layers 55 allowing the eye to move with respect to the epidermis, as in jawed fish, extraocular muscles develop and the eye erupts at the surface to form a vertebratestyle visual organ. Pdf early eye development in vertebrates researchgate. Optic cup morphogenesis ocm generates the basic structure of the vertebrate eye. Diencephalon of forebrain pax 6 key regulatory gene for eye development. A and b in the mouse, the optic vesicle forms as an outpouching of the forebrain at embryonic day 8. Initial stages of vertebrate eye development the formation of the vertebrate eye is an integral part of head formation and it requires the specification and regionalization of the anterior neural plate, evagination of the optic vesicles and finally, the cellular differentiation of the lens and retina. Even with these pessimistic values, the vertebrate eye would still evolve from a patch of photoreceptor cells in less than 364,000 years. Invertebrate and vertebrate eye development by ross l cagen. Early studies elucidated the fundamental embryology of the limb and identified the key signalling regions that govern its development. The rx homeobox gene is essential for vertebrate eye development. The vertebrate eye was one of the classic embryologic models in the early 1900s.
Further development varies considerably in different animal groups. B, c the overlying ectoderm differentiates into lens cells as the optic vesicle folds. Mathers5 and milan jamrich,1,2 1program in developmental biology, baylor college of medicine, houston, tx, usa, 2departments of molecular and human genetics and. This volume, which is part of the current topics in developmental biology series, highlights the exceptional advances over the past 20 years. The mature eye consists of anterior and posterior sectors.
A cameratype eye contains in the front a lighttight chamber and lens system, which focuses an image of the visual field on a light sensitive surface the retina in the back figure 2. Such differences in regenerative capacity are indicative of specific mechanisms that control the different types of regeneration. Purchase invertebrate and vertebrate eye development, volume 93 1st edition. The major development of the eye takes place between week 3 and week 10 and involves ectoderm, neural crest cells, and mesenchyme. Development of astrocytes in the vertebrate eye chenqi tao1,2 and xin zhang2 1stark neuroscience institute, indiana university school of medicine, indianapolis, indiana 2departments of ophthalmology, pathology, and cell biology, columbia university, new york, new york. Laxman khanal assistant professor, department of anatomy bpkihs, dharan 02042017 2. Subsequently, the initially single eye field splits into two symmetric retinal primordia that evaginate laterally from the forebrain and become proximodistally patterned into optic stalk and retina chow. Early evolution of the vertebrate eye fossil evidence.