Fig. 1

Pollen chamber formation within G. biloba ovule observed under the microscope. (a) At the early stage of ovule development, nucellar cells are morphologically similar in their size and shape. (b) At the later developmental stage, nucellar cells at the micropylar end (indicated by arrows), are elongated longitudinally, and distinguishable from other nucellar cells. (c) With the developmental process, pollen chamber (indicated by an arrow) is formed after the death and clearance of nucellar cells at the micropylar end within an ovule. Bars = 250 μm. Abbreviations: I, integument; M, micropyle; Nu, nucellus