普通针毛蕨颈卵器和卵的发育

蕨类植物卵发生是有性生殖研究的重要内容。真水龙骨类II的卵发生尚无人研究, 本文对该类群中的普通针毛蕨(Macrothelypteris torresiana)卵发生过程进行了光镜和透射电镜研究。结果显示: 卵细胞刚形成时, 与腹沟细胞紧密相连, 随着卵进一步发育, 卵细胞和腹沟细胞之间逐渐形成分离腔, 但孔区处卵细胞和腹沟细胞始终相连。随后, 卵细胞上表面有不定型物质堆积在质膜外, 形成一层加厚的卵膜, 孔区处没有卵膜覆盖的位置最后形成受精孔。在卵发育后期, 卵细胞核变得不规则, 近成熟时卵核产生大量核外突。卵发育过程中卵膜的出现、受精孔的产生以及核外突等特征, 与进化的真水龙骨类中其他蕨类植物的卵发生研究结果相似, 与薄囊蕨类中原始基部类群的卵发生现象有显著差别。由此可见, 普通针毛蕨属于进化类型。依据卵发生中卵膜和受精孔等特征推测原始薄囊蕨类经过里白类、桫椤类, 最终演化为水龙骨类。

Development of archegonium and oogenesis of the fern Macrothelypteris torresiana

Fern oogenesis is a vital process in sexual reproduction, yet Polypodia II oogenesis has not been studied. This paper studies sexual reproduction oogenesis of Macrothelypteris torresiana of Polypodiaceae. Our findings document oogenesis and egg movement throughout sexual reproduction. The appearance of egg envelope, the formation of fertilization pore and nuclear evaginations during the development of Macrothelypteris torresiana are similar to other pteridophytes in eupolypods, and are significantly different from those of the primitive basal groups in leptosporangiates. This indicates that Macrothelypteris torresiana may be a evolutionary fern. Based on the characteristics of the egg envelope and the fertilization pore, we infer that primitive leptosporangiates evolved into polypods after passing through gleicheniales and cyatheales.