B Chromosome tracking in 3D. The reconstructed images are viewed from the side of the metaphase plate. Signals are interpolated in the Z axis for visualization. White and red arrowheads, as well as red surfaces, indicate univalent-like chromosomes that underwent unbalanced predivision (premature segregation of sister chromatids). Scale bar = 4 μm. C Halving the recipient ooplasmic mass rescued chromosome alignment. The numbers of misaligned chromosomes and their parental origin were determined in 3D (n = 39 and 17 oocytes). Error bars show the standard deviation. Student's t-test was used to compare means. *P < 0.05. N.S., not significant. 