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After pollination, the pollen grain absorbs nutrients from the stigma; and develops a pollen
tube; it grows down the style to the embryosac; taking along the male nuclei;
The tube nuclei initiates and maintains pollen tube growth; while the generative nucleus
divides by mitosis;to form two male gamete nuclei; which follow behind the tube nucleus as the
pollen tube grows down the style;pollen tube enters the ovule through the micropyle; its tip
bursts open; while the tube nucleus disintegrates;one of the male gamete nucleus fuses with the
egg cell nucleus/oosphere/megaspore; to form the zygote;while the other fuses with the two
polar nuclei; to form a triploid nucleus; called the primary endosperm nucleus;
After fertilization, the zygote undergoes repeated mitotic divisions; to form an embryo
consisting of the plumule, radicle and seed leaves/cotyledons; primary endosperm nucleus
divide repeatedly,become separated by membranes; to form an (semi-fluid nutritive)
endosperm;
Ovary walls change into the pericarp; ovary changes/develops into a fruit; while ovules lose
water and become seeds; the integuments; change into seed coats/testa;
style/filaments/petals/sepals wither and fall off (or may persist);
Kavungya answered the question on May 13, 2021 at 13:27
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