Fig. 8
TEM analysis of COCs cultured for 3.5 h in the absence and in the presence of either uZnO or SiO2ZnO. A COC in control cultures. Scale bar 20 μm. B Detail of oocyte from a control culture. Scale bar 2 μm. C Cumulus cells from control culture, which appear well preserved and connected by desmosomal structures (white boxes). Scale bar 5 μm. D COC cultured with uZnO NPs. Scale bar 20 μm. E Detail of an oocyte treated with uZnO NPs, which shows lysosomes containing electrondense particles with peripheral sublocalization. EDX analysis confirmed the content of Zn and O (EDX spectrum). Scale bar 0.2 μm. F Cumulus cells treated with uZnO NPs display cytoplasmic vacuolation (asterisks) and several Zn and O containing lysosomes (inset) (EDX spectrum). Scale bar 5 μm. G COC cultured with SiO2ZnO NPs. Scale bar 20 μm. H Detail of an oocyte cultured with SiO2ZnO NPs; no Zn containing lysosomes are identified. Scale bar 0.5 μm. I Cumulus cells treated with SiO2ZnO NPs display moderate signs of degeneration such as cytoplasm vacuolation (asterisks). No lysosomes containing electrondense particles are identified. Scale bar 5 μm. ZP: zona pellucida; white arrows: oocyte plasma membrane; black arrows: lysosomes