丫蕊花(Ypsilandra thibetica Franch.)胚胎发育的研究Ⅰ.大孢子,雌配子体的发生以及淀粉粒的动态

本文主要应用石蜡切片方法,对丫蕊花心皮、胎座的个体发育,大孢子发生,雌配子体发生以及淀粉粒的动态进行了观察.并将花的外部形态特征与内部的发育阶段相联系.同时初步观察了减数分裂过程中胼胝质的变化.丫蕊花为倒生胚珠.双珠被、厚珠心.大孢子母细胞减数分裂之后,形成了线型,T型和交叉型三种四分体.胚囊发育为蓼型.成熟胚囊阶段,助细胞的珠孔端壁上分化出丝状器,反足细胞为多核,胚囊两侧的珠心细胞全部消失,胚囊紧贴于珠心表皮之下.在减数分裂前期,大孢子母细胞无胼胝质壁,二分体,四分体也只有横向的胼胝质壁,而侧壁则无.大孢子母细胞,二分体,早期四分体细胞中均无淀粉粒.在四分体阶段后期,合点端的有效大孢子中出现零星的淀粉粒.在以后整个雌配子体发生过程中,胚囊内都有淀粉粒的积累.观察表明:丫蕊花的胚胎发生过程中,有某些原始的特征,同时也有某些独具的特征.

A PRELIMINARY EMBRYOLOGICAL STUDY ON YPSILANDRA THIBETICA FRANCE. I. MEGASPOROGENESIS, MEGAGAMETCGEKESIS AND STARCH GRAINS DISTRIBUTION

Ypsilandra thibetica Franch., an ancient Liliaceous plant to south-western China, has not been investigated hitherto enibryologically.The ovule transforms its orientation from ortho- to anatropus ontogenetically. It is crssinucel-late and is inclosed by two integuments.The sequence of the stages of embryogenesis is closely correlated with the morphological variations of anthesis.The development of the embryo sac is of the Polygonum type with some features of its own, suth as; (1): T-shaped, linear shaped and crass typed tetrads are present with the chalazal megaspore functional. (2): At the mature embryo sac stage, all nucellar cells degenerate except some situated at the microphylar end. (3): In meiosis, the callos do not encircle megasporocyte, and only present the walls between the megaspores. (4): At the later stage of tatrads, starch grains are fund in the chalazal rnegaspore. In all megagametogenesis, the starch grains are present in embryo sac.