海金沙配子体发育及卵发生的显微观察

用光镜观察海金沙(Lygodium japonicum)配子体发育和卵发生。海金沙孢子为四面体形,具三裂缝,孢子萌发方式为密穗蕨型(Anemia-type);配子体的发育形态多样,通常丝状体长至3~5个细胞时通过顶细胞纵分裂发育为片状体,进而发育为心形原叶体,在心形原叶体上可产生精子器和颈卵器。但在培养过程中也可产生10个细胞以上的丝状体,这种丝状体发育成的片状体和原叶体形态通常不规则,只产生精子器,不产生颈卵器。原叶体发育是铁线蕨型(Adiantum-type),性器官是薄囊蕨型(Leptosporangiate-type)。切片观察海金沙颈卵器产生于生长点下方表面细胞,经两次分裂形成了顶细胞、初生细胞和基细胞。其中初生细胞再经两次不等分裂产生卵细胞、腹沟细胞和颈沟细胞,此时三个细胞紧密相连,随发育,颈沟细胞和和腹沟细胞退化,卵周围形成了分离腔,光镜观察显示成熟卵细胞上无典型卵膜形成,未观察到受精孔的结构。

Development of Gametophyte and Oogenesis of the Fern Lygodium japonicum

Gametophyte development and oogenesis of the fern Lygodium japonicum were studied using microscopy. The spores are tetrahedral and trilete. The spore germination pattern is the Anemia-type. The gametophyte development showed various forms. When the filaments length reached 3-5 cells, they can produce plate by longitudinal division of the apical cell, and finally formed the heart-shaped prothallus, which can produce antheridia(an) and archegonium(ar). However, the gametophyte can also produce 10 cell-lengthed filaments. These filaments usually produce irregular prothallus, which can produce antheridia and do not produce archegonia. The development of the prothallus is the Adiantum-type. Sex organs are the Leptosporangiate-type. Sections observations showed that the archegonium develops from a superficial initial cell under the growth point. Two divisions of the initial cell result in a tier of three cells, i.e. the upper cell, primary cell and basal cell. The primary cell finally develops into a neck canal cell, a ventral canal cell and an egg by two unequal divisions. These three cells were closely associated with each other. Then the neck canal cell and the ventral canal degenerated gradually. A separation cavity was formed around the matured egg. Light microscope observation showed that no typical egg envelope was formed in the surface of the egg and no fertilization pore was observed in the matured egg.