Fig. 4.

Time fluorescence images showing sperm [Ca²⁺]i increases promoted by STRV medium either containing normal 2 mM [Ca²⁺]e (A) or 100 nM [Ca²⁺]e (STRV EGTA) (B). Ionomycin in 2 mM [Ca2+]e (IONO 2 mM) was added as a control at the end of all recordings. In the right panels representative traces showing the [Ca²⁺]i changes observed in the two media containing the corresponding [Ca²⁺]e. Notice the STRV EGTA medium did not induce sperm [Ca²⁺]i responses. C. [Ca²⁺]i and AR time images of sperm exposed to STRV-EGTA medium after NUTR (top panel) or STRV EGTA pre-incubation (middle and lower panels) and then exposed or not to either progesterone (PROG) or ionomycin (IONO). D. Quantifications show the presence of EGTA in the STRV medium preincubation significantly reduces AR occurrence (for PROG-STRV p = 0.007, t = −3.5, n=4; for IONO-STRV p = 0.0335, t = −2.7 n=5) unless ionomycin is added at 15 sec (lower sequence). In all recordings black arrows indicate time 0’ of either STRV medium or agonists application, and the numbers at the bottom right of images are the time in seconds it was taken. t-Test was applied for statistical analysis, * indicates statistically significant differences, p value < 0.05.