FIG. 1.

Progesterone promotes an [Ca²⁺]i increase in Fluo-4 AM-loaded mice sperm. A) Image sequence showing sperm exposed to 40 μM progesterone (PROG) and recorded for 30 min. Sperm displayed an [Ca²⁺]i increase at different times during the experiment. At the end of the recording, ionomycin (IONO) was added as a viability control. B) Fluorescence changes corresponding to sperm 1–3 of the field recorded in A. C) Percentage of sperm displaying an [Ca²⁺]i increase in response to vehicle, 40 μM, and 100 μM progesterone addition. Black arrows indicate the time where progesterone and ionomycin were applied. These results were obtained by analyzing 319 sperm from 25 mice; statistically significant differences at *P < 0.05 and ***P < 0.001 when compared to vehicle.