关键词: 大车前, 合子, 原胚, 胚柄, 超微结构

Abstract: An experiment was conducted by using TEM to study the ultrastructural changes in zygote and proembryo of Plantago major L. The results were as follows：Embryonic development of Plantago major L. was epilobium type. With the development of zygote，cell wall gradually formed，the volume increased，the polarity inhanced，and starch began to store in plastids. The zygote divided into basal cells and apical cells in first cross division after the primary endosperm nucleus division. Basal cell formed a single line cells after several times division，which developed into suspensor. Apical cell formed embryoid body after several times cell division. There were very large cell nucleus with obvious nucleolus and many variety types of organelles in embryoid body cells. These organelles of embryoid body cells had strong meristematic ability and high metabolic ability. In the early stage of small ball embryo，nutrients were from the storage of zygote，absorption and transport by suspensor. In the early stage to middle stage of small ball embryo，the suspensor tissue developed rapidly by absorping nutrients from integument andtransporting them to embryoid body. In the late period of big ball embryo，suspensor disintegrated and embryonic body peripheral cells absorbed the degradation products of endosperm cells as the nutrients for embryonic development.

Key words: Plantago major, zygote, proembryo, suspensor, ultrastructure