| Cell replication and terminal differentiation in the embryonic chicken lens: normal and forced initiation of lens fibre formation. | |
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MedLine Citation:
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PMID: 6533255 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The relation between cell replication and lens fibre formation was studied in normal 5-day chicken embryos and in embryos in which the lens was reversed. After this microsurgery the epithelial cells were facing the retina and were forced to start fibre differentiation. Embryos were treated with [3H]thymidine followed by autoradiography or with Colcemid to induce metaphase arrest. About half of the control epithelial cells were actively replicating (in contrast, in the earliest stages of lens formation all cells are multiplying). Half of the non-dividing population was accounted for by the annual pad cells. The other half, probably in a resting phase (GO) of the cell cycle, was perhaps slightly more common in the central epithelium. This suggests that a germinative zone may be forming in the lens epithelium as early as 5 days of embryonic life. Normal epithelium had a cell cycle time of about 11 h, with S-phase, M, G1 and G2 lasting 5.5, 0.5, 2, and 3 h. After reversal the labelling index remained at control levels for about 4 h and then dropped to zero at 9 h. Similarly, the mitotic index gradually decreased to zero in 15. It appears that reversal forces the epithelial cells to cease replication when they reach G1. Cells already in GO may form fibres without first going through DNA synthesis. The very sharp boundary between dividing and non-dividing cells at the border of the optic cup suggests that the retina may regulate the irreversible cessation of cell replication associated with lens fibre differentiation. |
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Authors:
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J Zwaan; R E Kenyon |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Journal of embryology and experimental morphology Volume: 84 ISSN: 0022-0752 ISO Abbreviation: J Embryol Exp Morphol Publication Date: 1984 Dec |
Date Detail:
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Created Date: 1985-06-13 Completed Date: 1985-06-13 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 7906439 Medline TA: J Embryol Exp Morphol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 331-49 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cell Cycle Cell Differentiation Cell Division Chick Embryo Demecolcine / pharmacology Lens, Crystalline / cytology* Metaphase / drug effects Mitosis |
| Grant Support | |
ID/Acronym/Agency:
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EY-01002/EY/NEI NIH HHS; EY-03158/EY/NEI NIH HHS; EY-46406/EY/NEI NIH HHS |
| Chemical | |
Reg. No./Substance:
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477-30-5/Demecolcine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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