It is possible that for cows in diestrus, with concentrations
of progesterone greater than 6 ng/mL, as
observed for control cows, the additional progesterone had
little impact on rate of growth; thus, resulting in no effect
on the diameter of the preovulatory follicle. In some cases,
when in excessive concentrations, progesterone can induce
atresia and turnover of the dominant follicle