Document Detail


Mucocutaneous junction as the major source of replacement palpebral conjunctival epithelial cells.
MedLine Citation:
PMID:  10586935     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: The conjunctival epithelium performs an important role in the homeostasis and integrity of the eye. To protect the integrity of the ocular surface, these cells must be replaced from locally concentrated or randomly distributed foci of stem cells. These slow-cycling stem cells produce transient amplifying cells that undergo further divisions before becoming mature conjunctival epithelial cells. In the current study, the source of palpebral conjunctival cells was determined. METHODS: Adult rabbits were injected intraperitoneally with bromodeoxyuridine (BrdU) at a dose of 50 mg/kg body weight and killed after 1, 3, 5, and 7 days and 2 months. The orbital contents and eyelids were exenterated en bloc, frozen to maintain the orientation between the eyelids and globe, and sectioned in a parasagittal plane. Random midglobe sections were stained for the presence of proliferating cell nuclear antigen (PCNA). Additional sections were immunostained to detect BrdU-labeled conjunctival epithelial cells. BrdU-positive cells were counted in a series of 0.4-mm zones from the mucocutaneous junction of the eyelid, through the fornix and bulbar conjunctiva. A second set of rabbits received daily injections of BrdU for 2 or 4 weeks followed by a 2-month BrdU-free period before death and processing. RESULTS: In all eyelid sections examined, there was a focus of PCNA-positive cells in the mucocutaneous junction and a few scattered PCNA-positive cells along the length of the palpebral conjunctiva toward the fornix. In both the upper and lower eyelids, the peak concentration of BrdU-labeled cells/0.4-mm zone was located at progressively greater distances from the mucocutaneous junction in the animals killed at 1, 3, and 5 days respectively and was unidentifiable by 7 days. A focus of BrdU-labeled conjunctival cells remained within 1 to 2 mm of the mucocutaneous junction at all postinjection intervals. These were always found within one cell height of the basement membrane in the basal layer of the epithelium. In the long-term studies, BrdU-labeled nuclei were retained at the mucocutaneous junction. CONCLUSIONS: The mucocutaneous junction of the conjunctival epithelium is a source of actively dividing transient amplifying cells that migrate toward the fornix at a rate of approximately 1.7 mm/d with a transit time of approximately 6 days. Long-term retention of label at the mucocutaneous junction indicates that slow-cycling stem cells are present at this location. It appears that most palpebral conjunctival epithelial stem cells are located near the mucocutaneous junction. These results are not necessarily at variance with previous studies, but they diminish the relative importance of the forniceal region in palpebral conjunctival homeostasis. The mucocutaneous junction may provide a therapeutically significant source of replacement conjunctival cells.
Authors:
J D Wirtschafter; J M Ketcham; R J Weinstock; T Tabesh; L K McLoon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  40     ISSN:  0146-0404     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  1999 Dec 
Date Detail:
Created Date:  1999-12-09     Completed Date:  1999-12-09     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  3138-46     Citation Subset:  IM    
Affiliation:
Department of Ophthalmology, University of Minnesota, Minneapolis 55455, USA. wirtsch@maroon.tc.umn.edu
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MeSH Terms
Descriptor/Qualifier:
Animals
Bromodeoxyuridine / metabolism
Cell Count
Cell Movement / physiology*
Conjunctiva / cytology*,  physiology
DNA / biosynthesis
DNA Replication / physiology
Epithelial Cells / cytology*,  physiology
Eyelids / cytology*,  physiology
Mucous Membrane / cytology,  physiology
Proliferating Cell Nuclear Antigen / metabolism
Rabbits
Skin / cytology*
Stem Cells / cytology,  physiology
Grant Support
ID/Acronym/Agency:
EY07935/EY/NEI NIH HHS
Chemical
Reg. No./Substance:
0/Proliferating Cell Nuclear Antigen; 59-14-3/Bromodeoxyuridine; 9007-49-2/DNA

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