EARLY EMBRYOGENESIS IN ARABIDOPSIS-THALIANA .1. THE MATURE EMBRYO SAC
EARLY EMBRYOGENESIS IN ARABIDOPSIS-THALIANA .1. THE MATURE EMBRYO SAC
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DOI：
10.1139/b91-062
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发表时间：
1991-03-01
期刊：
影响因子：
--
通讯作者：
ERNI, S
中科院分区：
文献类型：
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作者：
MANSFIELD, SG;BRIARTY, LG;ERNI, S
拟南芥具有蓼型七细胞八核巨型配子体；每种细胞类型都表现出不同形式的结构特化。卵器细胞高度极化；卵有一个大的珠孔液泡和合点位置的核，而助细胞则相反。在卵器细胞的合点区，尽管质膜紧密接触，但没有细胞壁边界。两个助细胞之间的共同壁薄且不规则，并包含胞间连丝连接。助细胞质内含有丰富的细胞器；粗面内质网的轮廓出现在大量平行堆叠的池中，并且大量线粒体聚集在丝状装置附近。卵细胞的细胞质处于静止状态；核糖体浓度以及网体和内质网的频率明显较低，质体分化较差。中央细胞长且呈空泡，有一个大的二倍体核；极核的融合发生在胚囊成熟之前。细胞质含有大量积累在细胞核周围的壳中的含淀粉质体。高核糖体浓度以及不存在液泡和盘状体是反足细胞细胞质的典型特征。所有反足细胞均通过胞间连丝相互连接，并与珠心和中央细胞相连。
Arabidopsis thaliana has a seven-celled eight-nucleate megagametophyte of the Polygonum type; each cell type displays a different form of structural specialization. The egg apparatus cells are highly polarized; the egg has a large micropylar vacuole and chalazally sited nucleus, whereas the opposite is true for the synergids. At the chalazal region of the egg apparatus cells there are no cell wall boundaries, although their plasmalemmas are in intimate contact. The common wall between the two synergids is thin and irregular and contains plasmodesmatal connections. The synergid cytoplasm is rich in organelles; profiles of rough endoplasmic reticulum appear in masses of parallel stacked cisternae, and large accumulations of mitochondria occur adjacent to the filiform apparatus. The egg cell cytoplasm is quiescent; ribosome concentration and frequencies of dictyosomes and endoplasmic reticulum are noticeably lower and plastids are poorly differentiated. The central cell is long and vacuolate with a large diploid nucleus; fusion of the polar nuclei occurs prior to embryo sac maturity. The cytoplasm contains numerous starch-containing plastids accumulated in a shell around the nucleus. A high ribosome concentration and the absence of vacuoles and dictyosomes typifies the antipodal cell cytoplasm. All antipodal cells are interconnected by plasmodesmata as well as being connected to the nucellus and central cell.