Localization of BRET-QD in boar spermatozoa. (A) Detection of QD fluorescence using Confocal Microscopy. Overlays of bright field and fluorescence lights corresponding to spermatozoa incubated with 0 and 1 nM BRET-QD are shown in (a) and (b), respectively. Fluorescence detection in spermatozoa incubated with 1 or 5 nM BRET-QD is shown in (c) and (d), respectively. (B) Localization of QD using Transmission Electron Microscopy (TEM). Micrographs (e) and (f) respectively show transversal and longitudinal cross sections of the head. A transversal cross section of the tail is shown in (g). Red and black arrows respectively indicate QD within the cytoplasm and the surface plasma membrane. Acrosome and nucleus areas are indicated as Ac and N, respectively. Scale bars = 10 μm in (a), (b), (c) and (d), or 0.5 μm in (e), (f) and (g).