| 翻訳と辞書 |
| Eye development ： ウィキペディア英語版 |
Eye development
Eye formation in the human embryo begins at approximately 3 weeks into embryonic development and continues through the tenth week.〔Ort, D., David, H., ("Development of the Eye" ). Retrieved 22 April 2015.〕 Cells from both the mesodermal and the ectodermal tissues contribute to the formation of the eye. Specifically, the eye is derived from the neuroepithelium, surface ectoderm, and the extracellular mesenchyme which consists of both the neural crest and mesoderm.() Neuroepithelium forms the retina, ciliary body, iris, and optic nerves. Surface ectoderm forms the lens, corneal epithelium and eyelid. The extracellular mesenchyme forms the sclera, cornea, blood vessels, muscles, and vitreous.
The eye begins to develop as a pair of optic vesicles on each side of the forebrain at the end of the 4th week of pregnancy. Optic vesicles are outgrowings of the brain which make contact with the surface ectoderm and this contact induces changes necessary for further development of the eye. Through a groove at the bottom of the optic vesicle known as choroid fissure the blood vessels enter the eye. Several layers such as the neural tube, neural crest, surface ectoderm, and mesoderm contribute to the development of the eye.
Eye development is initiated by the master control gene Pax-6, a homeobox gene known as Andridia in humans, small eye in mouse, and eyeless in Drosphilia. The Pax-6 gene locus is a transcription factor for the various genes and growth factors involved in eye formation.〔〔Keller, A. M. V., ("Embryonic Development of the Eye" ). Retrieved 22 April 2015.〕 Eye morphogenesis begins with the evagination, or outgrowth, of the optic grooves or sulci. These two grooves in the neural folds transform into optic vesicles with the closure of the neural tube.〔Fuhrmann, S., Levine, E. M. and Reh, T. A. (2000). “Extraocular mesenchyme patterns the optic vesicle during early eye development in the embryonic chick”. Development 127, 4599-4609.〕 The optic vesicles then develop into the optic cup with the inner layer forming the retina and the outer portion forming the retinal pigment epithelium. The middle portion of the optic cup develops into the ciliary body and iris.〔LifeMap Science, Inc. ("Embryonic and Postnatal Development of the Eye" ). Retrieved 22 April 2015.〕 During the invagination of the optic cup, the ectoderm begins to thicken and form the lens placode, which eventually separates from the ectoderm to form the lens vesicle at the open end of the optic cup.〔 Further differentiation and mechanical rearrangement of cells in and around the optic cup gives rise to the fully developed eye.
==Sequential inductions==
This development is an example of sequential inductions where the organ is formed from three different tissues:
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Eye development」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|