摘要
本文对山茱萸(Cornus officinalis Sieb.et Zucc.)的大孢子发生和雌配子体发育进行了研究,并用组织化学方法对胚珠组织中的RNA、DNA、蛋白质和不溶性多糖进行了测定观察.山茱萸的胚珠为单珠被、薄珠心,并在发育过程中形成结构特殊的珠被绒毡层、承珠盘和珠孔塞.孢原细胞直接起大孢子母细胞作用.合点端大孢子具功能.胚囊发育属寥型.在开花前2个月时,成熟胚囊中的2个极核融合次生核,3个反足细胞退化,形成由一个3-细胞卵器和一个具次生核的中央细胞构成的4-细胞雌配子体.某些助细胞中的核位于近合点端,珠孔端为大液泡所占据,次生核通常位于胚囊的合点端.对珠被细胞的RNA、DNA、蛋白质和不溶性多糖的染色均呈较强的正反应.在成熟后期的珠被各层细胞中,除多糖颗粒外,对其他几种物质的检测结果均表现出由外向内形成一个较明显的浓度梯度,即珠被绒毡层着色最深.在成熟的雌配子体中,以卵细胞对Brachet反应最强,其次是中央细胞.卵细胞含大量淀粉粒,助细胞和中央细胞含淀粉粒少,且颗粒比卵细胞中的小.卵细胞和中央细胞呈Feulgen负反应.
The macrosporogenesis, the development of the female gametophyte and the histochemical aspects of the ovules in Cornus officinalis Sieb. et Zucc. have been studied. The main results obtained are summarized as follows:
The ovule is unitegminous and tenuinucellatae. During the development of the ovule, some special structures are formed, e.g.integumentary tape-tum, hypostase and obturator which originates from integument. A single hypodermal archesporial cell differentiates in the nucellus and it functions directly as the megaspore mother cell. The cell enlarges and divides to form two dyad cells which may be unequal. The megaspore tetrads are mostly linear, but at times T-shaped. The chalazal megaspore is functional. The development of the embryo sac conforms to the polygonum type. Two polar nuclei fuse into the secondary nucleus and three antipodal cells degenerate soon after the embryo sac reaches its maturation, which results in the embryo sac and has become a 4-celled female gametophyte that consists of only a 3-celled egg apparatus and a central cell with a secondary nucleus in two months before the flower comes out, The nucleus of the synergid is mostly located in the micropylar half of the cell, but the nucleus of some synergid is located in the chalazal part of the cell, while the microplar half of the synergid is occupied by one large vacuole, surrounded by a thin layer of cytoplasm. The secondary nucleus of the central cell is usually located on the chalazal part of the embryo sac.
Histochemical studies show that the integument is of a higher intensity of staining for RNA, DNA, total proteins and polysaccharides at the mature embryo sac stage, and that later a gradient develops in their density of staining from outside towards the embryo sac. Therefore, the integumentary tapetum stains densely for RNA, DNA and proteins. But it lacks starch grains, which may be due to their rapid mobilization by the secretion of hydrolytic enzymes. The egg cell is characterized by strong positive Brachet reaction, abundant starch grains and negative Feulgen reaction in mature female gametophyte. The symergids and the central cell contain fewer and smaller starch grains than the egg has. The secondary nucleus of central cell gives a negative reaction to Feulgen stain.
出处
《杭州大学学报（自然科学版）》
CSCD
1991年第1期73-82,共10页
Journal of Hangzhou University Natural Science Edition
基金
国家自然科学基金
关键词
雌配子体
大孢子
山茱Yu
Cornus officinalis
female gametophyte
integumentary tapetum
hypostase
obturator
