蕨受精作用的细胞学观察

为了阐明进化蕨类受精作用的特点和细胞学机制,该文采用透射电镜观察了蕨(Pteridium aquilinum var.latiusculum)受精作用的主要过程,观察结果显示:(1)蕨精子通过受精孔进入卵细胞,多数情况下,该精子的螺旋运动先在受精孔的下方产生一个受精腔,然后精子再与卵细胞质融合。(2)第一个精子的这种延迟的螺旋运动和因精子的钻入而引起的卵细胞固缩反应可能是阻止多精受精的重要因素。(3)卵发育时期产生的核外突在受精后仍能持续12 h,然后与核本体分离,逐渐在细胞质中消解。(4)合子通过其后方细胞质的液泡化而建立了水平极性,此后再进行细胞分裂。该研究观察到了进化蕨类受精作用过程中的一些新现象,包括产生受精腔、卵细胞固缩反应、核外突的命运以及合子极性建立等,这有助于理解蕨类植物的受精作用机制及有性生殖的演化。

Cytological Observations on the Fertilization of the Fern Pteridium aquilinum var.latiusculum

The fertilization of the fern Pteridium aquilinum var.latiusculum are observed using electronic microscopy.(1)The spermatozoid penetrates the egg through the fertilization pore.The gyratory motion of the spermatozoid serves to form a fertilization cavity just beneath the fertilization pore and then enters the egg cytoplasm.(2)The prolonged gyratory motion of the first spermatozoid and irritability reaction caused by the sperm penetration may contribute to block the polyspermy.(3)The nuclear evaginations persist 12 h and then detached from the nuclear body and finally are digested in the zygote cytoplasm.(4)The zygote establishes a horizontal polarity by vacuolization of the cytoplasm in the posterior part of the zygote before the zygote divides.The present study provides some new insights into the cytological mechanism of fertilization in ferns,which contribute to understand the cytological mechanism of the fertilization and evolution of the sexual reproduction of the ferns.