Circadian variation in the mitotic rate of the rat corneal epithelium

Håskjold, Erling; Refsum, Sigvald; Bjerknes, Rolf

doi:10.1007/bf02890063

Cited by 22 publications

(4 citation statements)

References 8 publications

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“…The mean cell renewal time of the corneal epithelium is very short and has been estimated to about 12 days in the rat corneal epithelium (Haaskjold et al 1989). The descendants of a peripheral located cell will need about 1 year to reach the centre of the cornea (Haaskjold et al 1989).…”

Section: Discussionmentioning

confidence: 99%

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UVB‐induced formation of (6–4) photoproducts in the rat corneal epithelium

Estil

Olsen

Huitfeldt

et al. 1997

Acta Ophthalmologica Scandinavica

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ABSTRACT. The induction of DNA photoproducts in rat corneal epithelium was studied after in vivo exposure to different doses of ultraviolet B light at 297 nm. Affinity-purified antibodies with a major specificity against UV-induced (6-4) photoproducts were used. The results indicate a dose dependent formation of (6-4) photoproducts. Even a minimal erythema dose (25 mJ/cm2) produced (6-4) photoproducts, demonstrating that DNA damage occurs in corneal tissue following exposure to biologically relevant doses of UVB light.

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Section: Discussionmentioning

confidence: 99%

“…The descendants of a peripheral located cell will need about 1 year to reach the centre of the cornea (Haaskjold et al 1989). In general,corneal neoplasms are mostly reported to involve the limbus (Pizzarello & Jakobiec 1978).…”

Section: Discussionmentioning

confidence: 99%

UVB‐induced formation of (6–4) photoproducts in the rat corneal epithelium

Estil

Olsen

Huitfeldt

et al. 1997

Acta Ophthalmologica Scandinavica

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“…Circadian variations of the proliferation of the corneal epithelium have previously been demonstrated in the steady-state situation (1)(2)(3)(4)(5). The aim of the present study was to investigate if circadian variations influence the regenerative response in the corneal epithelium.…”

Section: Introductionmentioning

confidence: 98%

Time Dependency in the Regenerative Response to Injury of the Rat Corneal Epithelium

Sandvig

Haaskjold

Refsum

1994

Chronobiology International

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In the present study a central corneal epithelial defect (diameter 3.5 mm) was made in both eyes at 12:00 h in one group of rats and at 24:00 h in another group to see if the regenerative proliferation is influenced by circadian rhythms. The labeling index and the mitotic rate were registered at 4-h intervals in the perilimbal conjunctiva, the limbal area, and different parts of the cornea from the following morning until noon the day after that. The most pronounced regenerative proliferation was seen in the midperipheral and peripheral cornea. The regenerative response occurred in both groups 24-28 h after the injury, but was highly influenced by the normal circadian rhythms, especially with regard to the mitotic rate. The results support the theory that even regeneration is influenced by a circadian proliferative factor.

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“…This occurs either under physiological conditions (1,2) or following an abnormal epithelial loss (3). The renewal of the corneal epithelium has been studied using different techniques such as the arrest by colchicine (4), 5-bromo-2-deoxyuridine (BrdU) in association with immunohistochemistry (5,6), and [ 3 H]-thymidine ([ 3 H]-TdR) administration together with autoradiography (7,8). These studies have demonstrated that renewal of the corneal epithelium follows an established pattern for all types of stratified epithelia, in which cells originate in the deepest (basal) layer and are sloughed off at the most superficial stratum (6,8,9).…”

Section: Introductionmentioning

confidence: 99%

Maintenance of the corneal epithelium is carried out by germinative cells of its basal stratum and not by presumed stem cells of the limbus

Haddad

Sousa

2014

Braz J Med Biol Res

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The purpose of this investigation was to analyze the proliferative behavior of rabbit corneal epithelium and establish if any particular region was preferentially involved in epithelial maintenance. [3H]-thymidine was injected intravitreally into both normal eyes and eyes with partially scraped corneal epithelium. Semithin sections of the anterior segment were evaluated by quantitative autoradiography. Segments with active replication (on) and those with no cell division (off) were intermingled in all regions of the tissue, suggesting that the renewal of the epithelial surface of the cornea followed an on/off alternating pattern. In the limbus, heavy labeling of the outermost layers was observed, coupled with a few or no labeled nuclei in the basal stratum. This suggests that this region is a site of rapid cell differentiation and does not contain many slow-cycling cells. The conspicuous and protracted labeling of the basal layer of the corneal epithelium suggests that its cells undergo repeated cycles of replication before being sent to the suprabasal strata. This replication model is prone to generate label-retaining cells. Thus, if these are adult stem cells, one must conclude that they reside in the corneal basal layer and not the limbal basal layer. One may also infer that the basal cells of the cornea and not of the limbus are the ones with the main burden of renewing the corneal epithelium. No particular role in this process could be assigned to the cells of the basal layer of the limbal epithelium.

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Circadian variation in the mitotic rate of the rat corneal epithelium

Cited by 22 publications

References 8 publications

UVB‐induced formation of (6–4) photoproducts in the rat corneal epithelium

UVB‐induced formation of (6–4) photoproducts in the rat corneal epithelium

Time Dependency in the Regenerative Response to Injury of the Rat Corneal Epithelium

Maintenance of the corneal epithelium is carried out by germinative cells of its basal stratum and not by presumed stem cells of the limbus

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