Figure 3

Representative images of viable (A and B) and non-viable (C) BODIPY-cholesterol labelled boar spermatozoa following 2 h in non-capacitating and capacitating conditions. Note that labelling is higher in the apical sperm head than that in the post-equatorial region (indicated with arrows), which is most obvious in sperm that have not undergone capacitation (A). Upon incubation with capacitating conditions, BODIPY-cholesterol fluorescence reduces across the whole sperm head (B), which visually demonstrates the loss of this cholesterol analogue from the plasma membrane during capacitation. In non-viable spermatozoa, as assessed with propidium iodide (PI), BODIPY-cholesterol fluorescence was more intense across the entire sperm head, particularly in the equatorial region (C; indicated with an arrow), demonstrating potential intracellular labelling. Scale bar = 10 µm.