作 者 ：Liu Hong-e Lin Hung-(Lin hung-eh) and Wu Xia-ming
Keywords:Cryptomeria fortune, Embryogeny,
Abstract:The embryogeny of Cryptomeria fortunei was observed. By the middle of March the nucleus of functioning megaspore divides twelve times to form about 3000–4000 free nuclear female gametophyte. Wall formation is centripetal. By the end of May the archegonial complex containing 12–16 archegonia surrounded by jacket layer is present at the micropylar end of the gametophyte. The pollen grains are shed at the uninucleate stage. After pollination the pollen grains swell. The microspore nucleus moves to one side and divides to form a large generative nucleus and a small tube nucleus, The generative cell then divides to form a body cell and a stalk cell. When the pollen tube passed through the nucellus and reached the archegonial complex the nucleus of the body cell divides to form two male cells, generally only one of which enters the arehegonium and the fertilization takes place in the upper part of an egg cell. A number of eggs in an archegonial complex may be fertilized. After the fusion of the male nucleus with the egg nucleus, the zygote divides three times to form eight nuclei, which become organized into primary embryo cells and the open tier. The former are only two or three cells, while the latter has five or six cells open towards the top and divides to form the prosuspensor tier and the upper tier. Thus, the pro-embryo of Cryptomeria belongs to the standard type, according to Doyle (1963). Excepting the simple polyembryony, the cleavage polyembryony is a common character in the embryogeny of Cryptomeria. The mature embryo consists of the radicle, the hypocotyl, the plumule and three cotyledons. When the embryogeny of Cryptomeria fortunei is compared with that of C. japonica, there are many differences obtained. The number of archegonia in the archegonial complex of C. fortunei is less than that of C. japonica. The former does not form the archegonial chamber and the chalazal and lateral archegonia, while the latter does.
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