黑节草双受精过程及胚胎发育的研究

黑节草从传粉到受精约需１３０ｄ，精子在花粉管中形成，胚囊发育属蓼型胚囊，因反足细胞较早退化，故受精前胚囊多只由卵器和中央细胞组成。精卵核融合时，精核染色质进入卵核后凝集成颗粒状，并在原位与卵核的染色质融合，雌、雄性核仁一直维持至合子的第一次分裂期前。双受精作用正常，属于有丝分裂前配子融合类型，初生胚乳核发生２－３次分裂后逐渐退化消失，胚的发育局限于球形胚阶段。

STUDIES ON THE DOUBLE FERTILIZATION AND EMBRYOGENY IN DENDROBIUM CANDIDUM WALL. EX LINDL.

The study of the double fertilization and the embryogeny in Dendrobium candidum Wall. ex Lindl. shows that it takes about 130 days between pollination and fertilization. The generative cell divides and forms two sperms in the pollen tube before it reaches the embryo sac. The embryo sac development is of Polygonum type. Because antipodals are degenerated earlier, the embryo sac is composed of the egg apparatus and the central cell before fertilization. After the sperm nucleus enters the egg cell and fuses with the egg nucleus, the chromatin of the sperm nucleus turns granular, then fuses with that of the egg nucleus. The male and female nucleoli do not fuse until the zygote divides. The double fertilization proceeds normally and belongs to the type of premitotic syngamy. The primary endosperm nucleus degenerates gradually after it divides 2 - 3 times. The embryogeny stops in the stage of the spherical proembryo.