Figure 4. Flow cytometry measurement of intracellular calcium levels of sperm incubated in normal noncapacitating medium (NCM) or capacitating medium (CM) (A) (n = 5) and in the presence or absence of calcium in the media (B) (n = 4). Porcine sperm were incubated with 2.5 µM indo-1-AM before suspension in media with or without 2 mM calcium. Calcium levels were assessed at 0 and 3 hours of incubation. At least 10 000 sperm were evaluated, and those staining positively with propidium iodide were excluded from the analysis.