Paper - The development of the eyelids 1
Embryology - 28 Nov 2023    Expand to Translate
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Pearson AA. The development of the eyelids. Part I. External features. (1980) J. Anat.: 130(1): 33-42. PMID 7364662 PDF
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The Development of the Eyelids. Part I. External Features
Abstract
The sequence of developmental events leading to the formation of the eyelids is described in staged human embryos. By the end of the fourth week the optic vesicle lies close to the surface ectoderm. The surface ectoderm overlying the optic vesicle, in response to this contact, has thickened to form the lens placode (Stage 13). A few days later (about 32 days, Stage 14) the lens placode is indented by the lens pit. A day or two later (about 33 days, Stage 15) the lens pit is closed: however, the lens vesicle and optic cup lie close to the surface ectoderm and appear to press against the surface. Prior to the development of the eyelids, one small sulcus or groove forms above the eye (eyelid groove) and another below it (stage 16, 37 days). As these grooves deepen, in Stages 17-19, eyelid folds develop, first below, and then above, the eye. In Stages 19--22 the eyelid folds develop into the eyelids and cover more of the eye as the palpebral fissure takes shape. The upper and the lower eyelids meet at the outer canthus in Stage 19. The inner canthus is established a few days later in Stage 20. Closure of the eyelids is complete in Stage 23.
- Stage 13 - optic vesicle lies close to the surface ectoderm. The surface ectoderm overlying the optic vesicle, in response to this contact, has thickened to form the lens placode.
- Stage 14 - the lens placode is indented by the lens pit.
- Stage 15 - the lens pit is closed: however, the lens vesicle and optic cup lie close to the surface ectoderm and appear to press against the surface.
- Stage 16 - prior to the development of the eyelids, one small sulcus or groove forms above the eye (eyelid groove) and another below it
- Stage 17 18 - As these grooves deepen, in Stages 17 to 19, eyelid folds develop, first below, and then above, the eye.
- Stage 19 - The upper and the lower eyelids meet at the outer canthus.
- Stage 19 20 21 22 - the eyelid folds develop into the eyelids and cover more of the eye as the palpebral fissure takes shape.
- Stage 20 - The inner canthus is established.
- Stage 23 - Closure of the eyelids is complete.
Terms
- canthus - (pl. canthi) the outer or inner corner of the eye, where the upper and lower lids meet.
- lens placode -
- optic vesicle - (otocyst)
- palpebral fissure - the elliptic space between the medial and lateral canthi of the two open lids.
- sulcus - (Latin "furrow", pl. sulci) term used to describe a depression or groove.
Cite this page: Hill, M.A. (2023, November 28) Embryology Paper - The development of the eyelids 1. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_development_of_the_eyelids_1
- © Dr Mark Hill 2023, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
