Figure 3

Meiotic product behavior in control and YA-deficient embryos. In situ hybridization to X and Y chromosomes in 0–15 minute old embryos from X^X/Ya⁺Y (control) and X^X Ya²/Y (Ya²mutant) mothers mated to X/Y, Ya+males. Inset illustrations in each panel show the orientation of the embryo and positions of DAPI stained nuclei inside (not drawn to scale). Pink circles represent maternally derived nuclei, blue circles represent paternally derived nuclei. The X chromosome probe's signal is green, and the Y chromosome probe's is red. The paternal Y chromosome was Y, Ya⁺, and therefore is marked with both red and green signals. (A) In the control gonomeric-stage embryo shown, the polar body nuclei (one haploid maternal X^X chromosome-containing nucleus and two haploid maternal Y chromosome-containing nuclei) have not yet begun to associate. The gonomeric nucleus consists of a maternal X^X and paternal X chromosome, each seen as a single dot with the X probe. Control n = 28 embryos. (B-D) YA-deficient embryos with (B) two haploid X^X chromosome-containing nuclei and one haploid Y chromosome-containing nucleus (all of maternal origin), and one diploid nucleus which is a product of an association between a male Ya⁺Y chromosome-containing pronucleus and a haploid X^X chromosome-containing nucleus of maternal origin, (C) one diploid X^X-containing nucleus (of maternal origin), two haploid Y-containing nuclei (of maternal origin) and a Ya⁺Y containing male pronucleus, (D) one diploid X^X chromosome-containing nucleus (of maternal origin) and one triploid nucleus which is presumably a product of an association between a diploid Y chromosome-containing nucleus (or two Y-containing haploid nuclei) of maternal origin and a Ya⁺Y chromosome-containing male pronucleus. Ya2 n = 54 embryos. Bars = 4 μm for all panels.