金毛狗卵发育的观察

Development of Eggs of the Fern Cibotium barometz

用显微镜及透射电镜(TEM)对金毛狗(Cibotium barometz(L.)J.Sm.)卵的发育进行了观察,结果表明,金毛狗幼卵时期,卵细胞与腹沟细胞间的胞间连丝发达,卵细胞内含大量囊泡,质体含淀粉粒;随着生长发育,卵细胞与腹沟细胞之间产生分离腔,但腹沟细胞与卵细胞始终通过孔区相连,发育中期,卵细胞上方开始形成卵膜。电镜观察表明,卵细胞上方的卵膜较厚,由多层膜构成,侧方和下方的卵膜较薄;孔区上方无卵膜覆盖,从而形成受精孔。发育后期,卵细胞内囊泡消失,质体退化,卵核形成大量核外突。

The eggs of the fern Cibotium barometz（ L. ） J. Sm. were placed under light microscopy （LM） and transmission electron microscopy （TEM） to observe their development. At early stage of egg development the egg cell is well connected with the ventral canal cells through plasmodesmata, and contain numerous vesicles; the plastid contains obvious starch grains. With egg development, a separation cavity is formed between the egg cell and the ventral canal cell, but plasmodesmata still connects the egg and the ventral canal cell in the pore region. In the mid stage of egg development, an egg envelope is formed around the egg. In the mature stage of the egg development, the absence of egg envelope from the pore region where the egg and ventral canal cell were formerly interconnected produces a fertilization pore. The egg envelope is obviously thicker in the upper part of the egg than in the sides and lower part of the egg. The number of the vesicles is reduced in the egg cell and the plastids finally degenerate. At this stage, the nucleus produces numerous evaginations.