The kinetics of villus cell populations in the mouse small intestine. II. Studies on growth control after death of proliferative cells induced by cytosine arabinoside, with special reference to negative feedback mechanisms.

Cytosine arabinoside was used to kill large numbers of proliferating crypt cells in the mouse small intestine, and the recovery sequence was analysed in terms of the villus population size, the crypt population size, the crypt: villus and the net villus cell influx: because the crypt: villus ratio changed considerably, it was found appropriate to express the crypt population in terms of the crypt cell mass per villus in order to relate it to the villus cell population. All parameters measured showed a series of damped oscillations over the experimental period, and analysis of the relationship between the several population changes strongly suggest that negative feedback control mechanisms are responsible for the response pattern. The importance of measuring the correct kinetic parameters in growth control studies on renewing epithelia is stressed.