DNA fragmentation induced in SCF spermatozoa is not detectable by TUNEL after fertilization.

(a–d₁) A Vas-SCF zygote stained with TUNEL and counterstained with DAPI 5 hrs after sperm injection, and visualized by confocal microscopy. (e–h₁) A control zygote that was fixed and treated with DNAse I 10 mins after fertilization, and then stained by TUNEL. (i–l₁) A control zygote that was treated with DNAse I 5 hrs after fertilization. Double columns in each panel present the same embryo at different focal planes. S – sperm, Mc – maternal chromatin, M – maternal pronucleus, P – paternal pronucleus, Pb – polar body. All images are shown at the same magnification (bars = 20 µm).