Figure 10.

A model for bouquet formation in rye. Prebouquet meiosis is shown in (a): telomeres (circles) are polarized to one hemisphere of the nucleus, creating a “Rabl axis.” Nuclear pores (ovals) are distributed uniformly. (b) At the leptotene-zygotene transition, unknown mechanisms polarize both nuclear pores (top arrow) and telomeres (bottom arrow) in opposite directions. If movement of the nuclear envelope causes the difference in polarity between telomeres and nuclear pores, there must be differential movement at each membrane (arrowheads in top and bottom insets). (c) The result is a “bouquet axis” that is independent of the original Rabl axis.