Interspecies microinsemination assay was applied to examine the ability of minke whale haploid spermatogenic cells to induce Ca2+ oscillations and oocyte activation. Populations of round spermatids (RS), early-stage elongating spermatids (e-ES), late-stage elongating spermatids (1-ES) and testicular spermatozoa (TS) were cryopreserved in the presence of 7.5% glycerol on board ship in the Antarctic Ocean. Repetitive increases of intracellular Ca2+ concentration occurred in 0, 65, 81 and 96% of BDF1 mouse oocytes injected with the postthaw RS, e-ES, 1-ES and TS, respectively. A normal pattern of the Ca2+ oscillations was observed in 26–47% of the responding oocytes. Most oocytes that exhibited Ca2+ oscillations, regardless of the oscillation pattern, resumed meiosis (83–94%). These results indicate that whale spermatogenic cells acquire SOAF activity, which is closely related to their Ca2+ oscillation-inducing ability at the relatively early stage of spermiogenesis.
