Fig. 2. Meiotic defects in pam-1. (A) Time-lapse images of embryos from H2B::GFP strains. (A, parts a-c) In wild type, the pronuclei were apparent by DIC optics, within a few minutes of meiotic completion. (A, parts d-f) By contrast, the time of pronuclear appearance in pam-1 was significantly delayed. The condensed sperm chromosomes moved toward the oocyte chromosomes before the pronuclear envelopes formed. (B, part a) In wild type, chromosome segregation was clearly visible at the anterior cortex during meiosis II. (B, part b) In some pam-1 embryos, a DNA bridge was observed between the separating chromosomes in meiosis II. (B, part c) In some embryos this bridge persisted and the oocyte pronucleus and second polar body remained joined. Scale bar: 10 µm.