The presence of 5-hydroxymethylcytosine in pig oocytes and embryos. 5-hydroxymethylcytosine is detected in GV, zygote, and blastocyst (A–C, GV; D–F, zygote; G–I, blastocyst). Higher intensity is seen in potential ICM of blastocysts compared to TE. Green indicates 5-hydroxymethycytosine; red shows DNA (PI). Bar = 100 μm.