Fig. 9. Interactions between duet and dyad: meiotic chromosome stages. (A-J) duet/+ dyad/dyad. (K-N,W) duet dyad double mutant. (O-Q) duet/+ heterozygote. (R-T,V) dyad mutant. (A) Early zygotene. (B) Pachytene stage showing thickened but irregular chromosomes. (C) Diakinesis. Five bivalents are visible. (D) Aberrant diakinesis in which chromosomes have desynapsed to form ten univalents. (E) Extreme diakinesis in which both synapsis and sister chromatid cohesion have been lost to yield single chromatids. (F) Early anaphase 1 undergoing mixed segregation in which both univalents and bivalents are involved. (G) Late anaphase 1 showing approximately equal separation of chromosomes. Eight to ten chromosomes are present at each pole indicating an equal division. (H) Telophase 1. Equal division. Ten chromosomes are present at each pole. (I) Telophase 1. Unequal division. (J) Dyad formed after unequal division. (K) Zygotene. (L) Diakinesis involving 2 bivalents and 6 univalents. (M) Extreme diakinesis containing mostly single chromatids. (N) Prometaphase 1 having eight to ten thick diffuse chromosomes. (O,R) Normal diakinesis. (P,S) Metaphase 1. (Q,T) Telophase 1. (U,V) Cleared ovules of dyad (U) and duet dyad (V). (W) Metaphase 1. Scale bars: 12.5 µm (A-T,W) and 25 µm (U,V).