Open AccessSTUDIES ON THE MECHANISM OF DIURNAL VARIATION OF PROLIFERATIVE INDICES IN THE SMALL BOWEL MUCOSA OF THE RAT
Author(s) -
AlDewachi Hutaifa S.,
Wright Nicholas A.,
Appleton David R.,
Watson Alexander J.
Publication year - 1976
Publication title -
cell proliferation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.647
H-Index - 74
eISSN - 1365-2184
pISSN - 0960-7722
DOI - 10.1111/j.1365-2184.1976.tb01296.x
Subject(s) - variation (astronomy) , mechanism (biology) , diurnal temperature variation , biology , intestinal mucosa , medicine , geology , physics , atmospheric sciences , astrophysics , quantum mechanics
In the rat small bowel mucosa significant variation was found in both the labelling and the mitotic indices with time of day. The zenith and the nadir of labelling and mitotic activity coincided at 15.00 and 02.00 hours respectively. Small changes were found in the ‘cut‐off’ position, but this variation in proliferative compartment size was insufficient to account for the comparatively wider fluctuations in proliferative indices. Measurements of the rate of entry into mitosis, using metaphase arrest with vincristine at three widely separated times during the day, showed no significant change. Changes in the growth fraction or in the birth rate as measured cannot account for diurnal variation in the proliferative activity of the small bowel mucosa. We propose a hypothesis which involves diurnal fluctuations in the transit times through G 1 and through G 2 .