同型孢子蕨类植物卵发生和受精作用的细胞学研究新进展

New advances on the cytological studies of oogenesis and fertilization of the homosporous ferns

阐述了同型孢子蕨类植物有性生殖研究中卵发生和受精作用研究的一些新进展,包括颈卵器的形成、卵发育和受精作用3个方面.研究表明颈卵器来自于配子体生长点下方的原始细胞,其细胞质浓,核较大,位于细胞中央,原始细胞经2次分裂产生3层细胞,中间的为初生细胞,初生细胞经2次不等分裂形成1个卵细胞、1个腹沟细胞和1个双核颈沟细胞.卵成熟时,先后在卵细胞外产生分离腔和卵膜,进化的种类卵膜上形成了受精孔,首次证明腹沟细胞参与了受精孔的发生.受精作用研究表明精子是经受精孔钻入卵细胞的,受精时卵细胞剧烈地收缩和产生大的囊泡封阻受精孔可能是阻止多精受精的主要原因,接下来,受精卵经历核融合、雄细胞器的消化,合子细胞器的重排,质膜和细胞壁重建等过程,最终形成功能性合子.

The present paper described some new advances on the sexual reproduction of the ferns, mainly including detail processes on the production of the archegonia, the egg development and fertilization. The archegonia of the homosporous ferns are derived from the initial ceils under the growing point. The initial cells have dense cytoplasm and a large centrally placed nucleus. The ini- tial cell gives rise to a tier of three ceils by two divisions, middle of which is the primary cell. The primary cell undergoes two unequal divisions, and forms a neck canal cell, a ventral cell and an egg cell. During maturation, the egg cell becomes progressively isolated from the adjacent ceils by forming a separation cavity and an egg envelope. It is proved that the advanced ferns form a fertilization pore in the upper egg envelope. It is first discovered that the ventral canal cell takes part in formation of the fertilization pore. The fertilization experiment indicated that the spermatozoid penetrate the egg through the fertilization pore. Immediately shrinkage of the egg at the moment of the sperm penetration and formation of a large sac blocking the fertilization pore are proposed to be used to prevent polyspermy. Subsequently, the fertilized egg undergoes the nuclear fusion, digestion of the male organelles,rearrangement of the zygotic organelles and change of the cellular polarity of the zygote, rebuilding of the plasmalemma and the cell wall. Finally a functional zygote is formed.