TITLE

DIRECT VISUALISATION OF CELL SHEDDING FROM THE SMALL INTESTINE OF THE LIVING MOUSE

AUTHOR(S)
Watson, A.J.M.; Chu, S.; Montrose, M.H.
PUB. DATE
April 2003
SOURCE
Gut;Apr2003 Supplement 1, Vol. 52, pA8
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Introduction: Epithelial cells arise from stem cells at the base of the crypt and migrate up the crypt/villus axis to the tip of the villus where they are shed. The mechanism of cell shedding is unknown but two theories have been proposed. In the first, the shedding process is initiated by the cell undergoing apoptosis, which causes the cell to detach from the basement membrane and neighbouring cells, and thereby be shed into the lumen. In the second, the shedding process is initiated by neighbouring cells extending processes under the cell to be shed, forming tight functions that extrude the cell into the lumen. Once detached from the basement membrane the cell undergoes apoptosis as a secondary event. Methods: Mice were anaesthetised with inactin and loop of bowel brought out and opened. The mouse was placed on the stage of a two-photon microscope so the mucosal surface of the bowel could be observed. Nuclei were visualised with Hoechst 33258 1 mg/ml i.p. Caspase 3 activation was monitored with the cell permeont fluorescent dye 10 pM PhiPhilux (Oncoimmunin). Results: Optical sections were taken of the upper 30 pm of the mouse villi in vivo. Cell shedding was observed from the epithelial monolayer using time lapse imaging. While the cells were within the monolayer no changes in the morphology of the nuclei was observed. However, once shedding was complete cells in the intestinal lumen had condensed nuclei, suggestive of apoptosis. Cell shedding took place at a rate of 13.2 cells/hour/villus ± 3.5 (n: 4 mice). In a minority of cells caspase 3 was found to be activated at the same time as shedding took place. However, the majority of cells were shed without activation of caspase 3. The average rate of the cell moving out of the monolayer into the lumen was 0.83 µm/min ± 0.06, (n = 53 cells). This is more than twice the rate at which cells migrate up the villus. Conclusions: The majority of cells are shed without undergoing apoptosis. The...
ACCESSION #
9747307

 

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