银杏雌性生殖器官发育过程的显微观察

对银杏(Ginkgo biloba)雌性生殖器官的发育过程进行了连续显微观察.结果表明:功能大孢子经过大约1个月的分裂形成约5000个游离核后开始细胞化.授粉后约45天近珠孔端两侧各产生1个颈卵器母细胞.授粉后约50天.颈卵器母细胞平周分裂形成初生颈细胞和中央细胞.授粉后约55天,初生颈细胞垂周分裂形成2个扁平状次生颈细胞,之后次生颈细胞体积逐渐增大并突入颈卵器腔.授粉后约130天,2个次生颈细胞斜向分裂形成4个颈细胞,中央细胞不均等分裂形成腹沟细胞和卵细胞.套细胞起源于颈卵器母细胞的周围细胞,授粉后70天至受精作用发生前,套细胞内不断积累营养物质,且套细胞与中央细胞间的细胞壁以及套细胞之间角隅处的细胞壁均出现明显增厚现象.在受精及胚胎早期发育过程中,套细胞内营养物质逐渐消失,细胞逐渐解体.授粉后55天,2个颈卵器之间的一些细胞向上突起形成帐篷柱,之后帐篷柱体积逐渐增加,并突入颈卵器腔.自授粉后120天至受精前帐篷柱细胞内开始积累大量营养物质,随后这些营养物质在受精过程中被逐渐消耗.到了原胚游离核后期,帐篷柱的顶端细胞发生变形并解体.

Studies of the Development of Female Reproductive Organs in Ginkgo biloba

Microscopic observations of the development of female reproductive organs in Ginkgo biloba show that the functional megaspore produced about 5000 free nuclei after approximately 1 month of division, then the cell wall began to form. At about 45days 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 pedclinal division. At about 55 days after pollination, each primary neck cell produced 2 fiat secondary neck cells by anticlinal division, then the fiat 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.