Studies of the Development of Female Reproductive Organs in Ginkgo biloba
银杏雌性生殖器官发育过程的显微观察

Microscopic observations of the development of female reproductive organs in Ginkgo biloba show that the functional megaspore produced about 5 000 free nuclei after approximately 1 month of division, then the cell wall began to form. At about 45 days after pollination, 2 archegonial initials were observed near the micropylar. At about 50 days after pollination, each archegonial initial produced a primary neck cell and a central cell by periclinal division. At about 55 days after pollination, each primary neck cell produced 2 flat secondary neck cells by anticlinal division, then the flat secondary neck cells gradually increased in size and partly penetrated the archegonial chamber. At about 130 days after pollination, 2 secondary neck cells produced 4 cells by oblique division, and the unequal division of the central cell produced a ventral canal cell and an egg. Jacket cells were derived from cells surrounding the archegonial initials, and nutrients gradually accumulated in jacket cells from day 70 after pollination to fertilization. In addition, the cell walls between the jacket layer and central cells and in the angular domain among jacket cells were incrassated. Nutrients in the jacket layer gradually disappeared, and the jacket layer gradually degenerated during fertilization and early embryogenesis. The cells between the 2 archegonia protuberated and formed a camp column at 55 days after pollination, then the camp column gradually increased in size until it penetrated the archegonial chamber. Day 120 after pollination to fertilization showed a massive, gradual accumulation in nutrients in the camp column; these nutrients were gradually consumed during fertilization. At late proembryo stage, the cells in the top part of the camp column became gradually deformed and were degenerated.