Figure 2.

Male unreduced gamete formation in Brassica. a) A "giant" pollen grain in B. napus and several normal sized pollen grains; b) Putative viable unreduced (large, bright), viable reduced (small, bright) pollen and non-viable (shrunken, dull) pollen in an interspecific hybrid; c) B. napus × B. carinata (CCAB) pollen in cold (10°C day/5°C night) temperature); d) Two dyads produced by a B. napus × B. carinata (CCAB) hybrid in cold (10°C day/5°C night) temperature; e) beginning of telophase II in an interspecific hybrid, showing a tetrahedral nuclei arrangement within the cell as a result of normal, perpendicular spindle orientation, but with laggard chromosomes outside the nuclei and f) Anaphase II showing parallel spindles, a common mechanism of dyad formation in Brassica.