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Embryonic development of the cornea in the eye of the clearnose skate, Raja eglanteria: I. Stromal development in the absence of an endotheliumEmbryos of the clearnose skate, Raja eglanteria, develop in sea water at 20-22 degrees C, hatching after 82 +/- 4 days (Luer and Gilbert, Environ. Biol. Fishes, 13:161-171, 1985). Eyes develop as steadily enlarging spheres whose corneas have the same radius of curvature as the sclera. The cornea begins development as a 2-cell thick epithelium beneath which by Day 12 there is only a basal lamina and a wispy matrix separating it from the underlying lens. This matrix, modified by Day 16, is displaced on Day 22 by a few orthogonal plies of fibrillar primary stroma. Ply number increases to at least 13 by Day 30, reaching the final number of 20 +/- 2 by Day 42. Stromal fibroblasts (keratocytes) appear at the corneal periphery by Day 22, and in increased numbers by Day 30, a time at which no keratocytes are seen in the central stroma. However, by Day 40, many fibroblasts are present at the corneal periphery, invading the primary stroma between plies, occasionally reaching even the central cornea. By Day 53, keratocytes are present between all plies, from corneal periphery to center. Thickness of each ply in this secondary stroma increases, but the number of plies remains the same as in the primary stroma. Bowman's layer, non-invaded matrix beneath the epithelial basal lamina, is not evident until Day 53. Sutural fibers, first seen on Day 22, originate in the corneal epithelial basal lamina, traversing perpendicularly the plies of the primary stroma. Sutural fibers persist throughout development of the secondary stroma and into adulthood. In contrast to chicks, skate corneas remain transparent throughout development, and never form an endothelium.
Document ID
20050000329
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Conrad, G. W.
(Kansas State University Manhattan 66506)
Paulsen, A. Q.
Luer, C. A.
Spooner, B. S.
Date Acquired
August 22, 2013
Publication Date
July 1, 1994
Publication Information
Publication: The Journal of experimental zoology
Volume: 269
Issue: 3
ISSN: 0022-104X
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: EY00952
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Developmental Biology

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