Figure 4.

Metaphase I in PMCs with FDR in an F₁ wheat–rye hybrid. Rye centromeres labeled green; all chromatin counterstained red. (a) one bivalent present; most univalents congregate on the metaphase plate; all rye univalents have fused sister centromeres; (b) two bivalents; four rye univalents on the metaphase plate; two with fused and two with separated sister centromeres. All three rye univalents at the pole have fused sister centromeres; (c) one bivalent; univalents congregating on the metaphase plate; six rye univalents with separated sister centromeres; one may still have fused sister centromeres (arrowed); it appears to be in a bipolar attachment to the karyokinetic spindle; (d) six rye univalents on the metaphase plate with separated sister centromeres; one precocious rye univalent at the pole, with fused sister centromeres.