Fig. 10

Tentative model for the nucellar PCD during pollen chamber formation in G. biloba ovules. Ovules at the stage of pre-PCF (a) and post-PCF (b) are sectioned longitudinally. The black-boxed area in (a) contains nucellar cells at the micropylar end of ovule, which are to undergo PCD to generated a pollen chamber, bounded by the white-box in (b). Other nucellar cells, represented by a white-boxed area in (a), keep growth throughout the stages of PCF