findings are in disagreement with the results obtained from
the current experiment. Although the mean concentration
of progesterone between animals receiving a once-used
versus twice-used CIDR device (Fig. 1) was significantly
different (3.37 Æ 0.5 and 1.40 Æ 0.5 ng/mL, respectively; P ¼ 0.01), the concentration of plasma progesterone on the
day of device removal in an animal receiving a twice-used
CIDR was greater than 1 ng/mL, indicating a sufficient