红花胚珠和雌配子体发育

用石蜡切片法研究了红花的大孢子发生和雌配子体发育过程,得到以下结果：（１）胚珠发育为薄珠心类型,倒生胚珠,具单珠被。（２）胚囊发育蓼型。（３）有珠被绒毛层,珠被绒毡层起始于大孢子母细胞时期,单核胚囊阶段高度发育,受精后从合点端逐渐退化。珠孔塞细胞呈毛状。     

胚珠的类型

胚珠(ouvle)是种子植物的大孢子囊,种子的前身。裸予植物的胚珠裸露,被子植物的胚殊被包在子房内,子房内胚珠的数目随植物种类而不同。被子植物的胚珠由珠被(一般分内珠被和外珠被两层)和珠心两部分组成,珠心的中央是胚囊,珠被包在珠心的外面。珠被在珠心顶端的小孔叫珠孔,珠心的基部与珠被相连的部位叫合点。胚珠通过珠柄着生在胎坐上。由于胚珠各部分生长速度不同,可把胚珠区分为四大类。如果胚珠各部分的生长速度均匀一致,所生成的胚珠,珠孔、合点和珠柄三者在一条直线上,珠孔在珠柄的相对一端,这类     

观察胚珠发育的简便方法

被子植物的胚珠包藏在子房内,它是由子房内表皮的局部细胞平周分裂发展起来的。最初仅仅是一个小突起,称为胚珠原基。胚珠原基的前端将发育成珠心,基部将发育成珠柄。以后在珠心基部的细胞加速分裂,在珠心周围形成一环状突起并逐渐向上延伸把珠心围在中央,这就是珠被。珠被在珠心顶端留下一个小孔叫珠孔。受精前的胚珠由珠心、珠被、珠柄和珠孔组成。     

侧柏雌球果及其胚珠的发育

观察了侧柏（Ｐｌａｔｙｃｌａｄｕｓ ｏｒｉｅｎｔａｌｉｓ（Ｌ．）Ｆｒａｎｃｅ）胚珠的发育过程及后期球果苞片的结构变化。在北京,雌球果原基７月分化。通常一个球果有４对苞片,中部两对可育,靠球果顶端一对各产生一枚胚珠,其下一对各两枚。胚珠的发育顺序是向顶的,下部可育苞片腑部的两枚胚珠源于同一原基。胚珠原基分化成珠心和珠被,在发育过程中,珠被逐渐包围珠心,最后形成２烧瓶状的胚珠。１１月至次年１月,球果处     

小草蔻胚珠及雌配子体发育的研究

小草蔻（Alpinia henryi K.Schum）胚胎倒生,厚珠心,双珠被。内珠被独自成珠孔。造孢细胞,大孢子母细胞和四体时期,周缘细胞仅1层。四分体线形,少数三分体。合点在孢子具功能。成熟胚珠具有珠心冠原和承珠盘结构。胚囊发育属蓼型。成熟胚整,合点端狭长,形成盲囊。反足核不能构成细胞,是短命的。膜质假种皮的原基从外珠被和珠柄发生。     

荧光素钠在香子兰生活胚珠中的运输

在香子兰（Vanilla planifolia Andr.)未受精的胚珠中,外珠被只包到胚珠的下半部,荧光素钠自珠柄进入胚珠,先在胚珠含点区形成一个荧光中心,然后沿内珠被向珠孔端运输,在内珠被的珠孔端形成第二个荧光中心,不久卵器中显现荧光,受精以后,胚珠的外珠被向上延伸,与内珠被共同形成珠孔,荧光素钠经珠柄进入后向几个方向扩展;1．运至珠孔口处的外珠被中。2．沿珠柄一侧的外珠被向下至合点区;3．由合点区分别向内部和向远离珠柄一侧的外珠被扩展,香子兰胚珠中不具维管束,不过荧光素钠在内珠被中运输时,明显可见紧贴胚囊的内层细胞是其主要运输通道,胚囊成熟时,珠孔端一半在内珠被与胚囊之间有角质层相隔,胚囊合点端的一半与球心细胞间无角质层,营养物质无疑可由合点端进入胚囊,但是卵器是在内珠被珠孔端荧光中心形成后才出现荧光的,不能排除营养物质自珠孔端进入胚囊的可能性。     

荧光素钠在香子兰生活胚珠中的运输

在香子兰（Vanilla planifolia Andr.)未受精的胚珠中,外珠被只包到胚珠的下半部,荧光素钠自珠柄进入胚珠,先在胚珠含点区形成一个荧光中心,然后沿内珠被向珠孔端运输,在内珠被的珠孔端形成第二个荧光中心,不久卵器中显现荧光,受精以后,胚珠的外珠被向上延伸,与内珠被共同形成珠孔,荧光素钠经珠柄进入后向几个方向扩展;1．运至珠孔口处的外珠被中。2．沿珠柄一侧的外珠被向下至合点区;3．由合点区分别向内部和向远离珠柄一侧的外珠被扩展,香子兰胚珠中不具维管束,不过荧光素钠在内珠被中运输时,明显可见紧贴胚囊的内层细胞是其主要运输通道,胚囊成熟时,珠孔端一半在内珠被与胚囊之间有角质层相隔,胚囊合点端的一半与球心细胞间无角质层,营养物质无疑可由合点端进入胚囊,但是卵器是在内珠被珠孔端荧光中心形成后才出现荧光的,不能排除营养物质自珠孔端进入胚囊的可能性。     

银杏胚珠发育进程的解剖学研究

以15 a生银杏(Ginkgo bilobaL.)品种‘佛指’(G.bilobacv.‘Fozhi’)为材料,观察了授粉后胚珠结构、雌配子体发育和种皮分化形成的过程。结果表明:(1)授粉后2 d胚珠已分化出珠心、珠被和珠托组织,珠被顶端形成直径为162.16μm的珠孔与540.54μm长的珠孔道,珠心组织顶端形成长约520.83μm、最大直径约125.06μm的瓶状贮粉室,花粉粒经珠孔道已到达贮粉室并在其中停留;(2)雌配子体的发育先后经历了游离核阶段(授粉后5~30 d)和细胞化阶段(授粉后30~45 d),之后在近珠孔端形成颈卵器,其余部分发育为胚乳薄壁细胞,其营养物质的积累高峰期为授粉后60~80 d;(3)种皮分化与形成分别经历珠被分化期(授粉期至授粉后30 d)、种皮分化期(授粉后30~50 d)、种皮形成初期(授粉后50~80 d)、种皮形成期(授粉后80~90 d)。     

杉木大孢子叶球发育过程中形态结构的变化

以福州生长的成年杉木（Cunninghamia lanceolata（Lamb.） Hook.）为实验材料,采用数码相机实地拍照、体视镜、半薄切片以及扫描电镜等方法,从形态学、解剖学系统观察了杉木大孢子叶球的发育过程。结果显示,2011年10月底至11月初,杉木大孢子叶球形成,此时大孢子叶球呈绿色,体积较小;翌年3月中下旬,大孢子叶球成熟,进入传粉期,期间大孢子叶球经历了由绿变黄的颜色转变、体积增大以及苞片开张的过程。胚珠发育过程中,胚珠原基于1月上旬发生,1月中下旬珠被和珠心组织已分化形成;2月下旬,珠心组织继续发育,形态呈椭圆型,并在其上方形成贮粉室,周围的珠被组织继续生长包围珠心组织,形成珠孔道;3月初珠孔形成,开口达到最大,胚珠的体积继续增大;3月中下旬,胚珠珠孔处开始分泌传粉滴。授粉后,传粉滴消失,珠孔上方的组织停止生长,珠孔开口亦不再增大。研究结果表明杉木大孢子叶球从分化形成到发育成熟需要约5个月的时间,胚珠的形态结构经过长期演化形成了许多适应风媒传粉的结构特征。     

大叶杨配囊及胚珠的形成和发育

本文应用细胞化学方法研究了大叶杨胚珠、胚囊的形成和发育过程中核酸、蛋白质及不溶性多糖的分布和消长。大孢子母细胞、大孢子四分体及功能大孢子中含较少不溶性多糖,但却含丰富的RNA和蛋白质。功能大孢子经分裂发育成八核的蓼型胚囊。四核胚囊开始积累细胞质多糖,成熟胚囊中除反足细胞外充满淀粉粒。反足细胞形成后不久即退化。助细胞具多糖性质的丝状器,受精前两个助细胞退化。卵细胞核对Feulgen反应呈负反应。二极核受精前由胚囊中部移向卵器,与卵器接触后融合形成次生核。发育早期的胚珠为厚珠心,双珠被。晚期,内珠被退化,故成熟胚珠为单珠被。四核胚囊时期,珠孔端珠心组织退化,胚囊伸向珠孔形成胚囊喙。合点端珠心组织含丰富的蛋白质和核酸,这一性质与绒毡层性质相似,可能涉及胚囊的营养运输。胚囊的营养来源于子房和胎座细胞内贮存的淀粉粒。     

Nucellar beak structure and pollen tube growth in Cucurbitaceae

The nucellar beak is a proboscis-like outgrowth of the nucellus at the micropylar end, being the obligatory path for the pollen tube entering the ovule. Among the few angiosperm families with nucellar beak, Cucurbitaceae is remarkable because the pollen tube may develop at least two types of growth within the nucellar beak: tubular and ampulliform. Wondering about the possibility that Cucurbitaceae ovules may express some histological variation that could be related to pollen tube growth within the nucellar beak, we performed a compared anatomical and histochemical study of the nucellar beak and the pollen tube growth of ten species of Cucurbitaceae. Results show that Cucurbitaceae ovules are diverse in size and proportions (of integuments, nucellar body, and nucellar beak), and they have at least four types of nucellar beak histology: pectic-tracked, secretory-like, amylaceous, and mixed. Amylaceous and mixed nucellar beaks are related to the ampulliform growth of the pollen tube, which could have appeared independently in most derived tribes of Cucurbitaceae, although information about nucellar beak structure in the basal tribes is still needed. In addition, the understanding of the relation between amylaceous nucellar beaks and the ampulliform growth of the pollen tube, whose function is still to be discovered, might open the possibility of a unique model of pollen tube-ovule co-evolution in angiosperms.     

A pattern of unique embryogenesis occurring via apomixis in Carya cathayensis

Apomixis represents an alteration of classical sexual plant reproduction to produce seeds that have essentially clonal embryos. In this report, hickory (Carya cathayensis Sarg.), which is an important oil tree, is identified as a new apomictic species. The ovary has a chamber containing one ovule that is unitegmic and orthotropous. Embryological investigations indicated that the developmental pattern of embryo sac formation is typical polygonum-type. Zygote embryos were not found during numerous histological investigations, and the embryo originated from nucellar cells. Nucellar embryo initials were found both at the micropylar and chalazal ends of the embryo sac, but the mature embryo developed only at the nucellar beak region. The mass of the nucellar embryo initial at the nucellar beak region developed into a nucellar embryo or split into two nucellar proembryos. The later development of the nucellar embryo was similar to the zygotic embryo and progressed from globular embryo to heart-shape embryo and to cotyledon embryo.     

小麦珠心细胞衰退过程酸性磷酸酶的超微细胞化学定位(英文)

采用磷酸铅盐沉淀技术对小麦（ Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ Ｌ．） 珠心细胞衰退过程进行了酸性磷酸酶的超微细胞化学定位研究。结果显示,在未有明显衰退迹象的一些珠心细胞中,酸性磷酸酶只出现在细胞核轻微凝聚的染色质上。随珠心细胞衰退程度的逐渐增大,其衰退特征越来越明显,酸性磷酸酶依次在细胞质中较小液泡、细胞壁、线粒体、质体以及内质网等结构上出现活性反应。紧连胚囊的珠心细胞衰退程度最大,细胞严重变形,酸性磷酸酶定位于细胞绝大部分结构中,但此时变形的细胞核则无酸性磷酸酶活性反应。研究结果表明,小麦珠心细胞的衰退过程中,酸性磷酸酶存在一个有规律的变化,支持珠心细胞的衰退是属于细胞程序性死亡类型的观点     

小麦珠心细胞衰退过程中ATP酶的超微细胞化学定位

采用磷酸铅沉淀技术对小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ ）珠心细胞衰退过程进行了ＡＴＰ酶的超微细胞化学定位。初始衰退的珠心细胞,ＡＴＰ酶只定位于细胞膜上,其它部位未见有ＡＴＰ酶活性。衰退中期的珠心细胞,细胞膜上ＡＴＰ酶活性减弱并逐渐消失;细胞核染色质和细胞质中一些细胞器上存在ＡＴＰ酶活性。在严重衰退的珠心细胞中,只在细胞核染色质上存在ＡＴＰ酶活性。珠心细胞的细胞核以两种方式衰退。衰退的细胞核染色质碎片仍存在ＡＴＰ酶活性,并向胚囊方向转移。推测小麦珠心细胞衰退过程中细胞膜上ＡＴＰ酶变化反映了珠心细胞生理状态转变;细胞核染色质上ＡＴＰ酶与其形态变化和运动等有关     

花椒球心胚及胚乳的发生和发育

对花椒珠心胚及胚乳的发生和发育过程进行了详细的细胞学及细胞学研究。主要研究结果如下;珠心胚发生前,有性胚囊发育过程中从大孢子发生到胚囊形成的各个阶段均可发生退化,退化频率５０％,未退化的胚囊发育成熟,成熟胚囊仅含卵器和两个极核。卵器最终退化,极核不经受精自发形成胚肥。当胚乳游离核达到１５或３２个时,最早的珠心胚原始细胞由靠近胚囊球孔端的珠心细胞分化形成。随着子房生长,多个原始细胞持续不断地从珠孔端     

Programmed cell death of Pinus nucellus in response to pollen tube penetration

In ovules of Pinus densiflora, pollen tubes elongate and branch into the nucellar tissue in the direction of the female gametophyte. After pollination, nucellar cells located around the pollen grain and tube die off. We showed here that the nuclei of the nucellar cells were stained by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick end labeling). The number of TUNEL-positive cells increased during pollen tube growth. The tips of pollen tube branches protruded into the nucellar cells to form a convex-concave junction. At this junction, the cell membrane of nucellar cells was separated from the cell wall and the protoplast shrank. Small vesicles and amorphous materials were released from the protoplast into the space between the cell membrane and wall. Vacuoles were collapsed, chromatin was condensed, and mitochondria and plastids were deteriorated in the shrunken protoplast. Agarose gel analysis of DNA isolated from the ovules showed a DNA ladder, suggesting that the nuclear DNA had undergone internucleosomal cleavage. These results suggest that nucellar cells undergo programmed cell death in response to pollen tube penetration with some features resembling apoptosis and other features peculiar to nucellar cells.     

花椒珠心胚的超微结构及珠心细胞ATP酶的细胞化学定位

应用透射电镜对花椒（Xanthoxylum bungeanum Maxim)珠心胚原始细胞,多细胞原胚和此时期的珠心细胞及其ATP酶的分布进行了详细的观察,珠心胚原努细胞具厚的细胞壁,明显分为电子致密的外层和电子透明的内层,无胞间连丝,大的核中未见核仁,细胞质富含细胞器,多细胞原胚的壁比原始细胞的薄,电子透明,均质,具胞间连丝,核体积增大,核仁1至2个,细胞质中细胞数的数量明显增加,珠孔端的珠心细胞比胚性细胞体积大,细胞液泡化程度高,细胞质稀薄而呈现衰退趋势,ATP酶分布于液泡膜及液泡液中,与胚性细胞相接触的最内层珠心细胞胞质降解,核严重变形,最终细胞解体,此时无ATP酶活性反应。     

Ultracytochemical Localization of ATPase Activity in the Degenerating Nucellar Cells of Wheat During Degeneration

Ultracytochemical localization of ATPase activity was carried out using a lead phosphate precipitation technique in the nucellar cells of wheat during degeneration. ATPase was only localized on the plasma membranes of nueellar cells at the. early degenerative stage, then decreased and disappeared at the mid-degenerative stage. Meantime it was also observed in the nuclear chromatin and some cytoplasmic organelles. ATPase activity was only observed in the nuclear chromatin in the extremely degenerated nucellar cells. Two patterns of unclear degeneration was found in the degenerated nucellar cells. A lot of small fragments with ATPase from the degenerated nuclei moved toward the embryo sac. It is suggested that the change of ATPase activity on the plasma membranes is related to the physiological change of nucellar cells, and that in the nuclear chromatin is associated with the stages movement of chromatin during the process of nucellar cells degeneration.     

Ultracytochemical Localization of Acid Phosphatase in Nucellar Cells of Wheat During Degeneration

The distribution of acid phosphatase activity in nucellar ceils of wheat ( Triticum aestivum L. ) during degeneration has been studied using the lead precipitation method at the electron microscopic level. Acid phosphatase was localized in the slightly condensed nuclear chromatin in nucellar cells without any sign of ultrastructural degeneration. As the nuceilar cells started degenerating, the enzyme activity in the cell was observed, in the order from small vacuoles to cell walls, mitochondria, plastids and endoplasmic reticulum. Enzyme activity was the highest in most components of the nuceilar ceils adjacent to the embryo sac where the degeneration of nucellar cells was the strongest, but it was not observed in the nuclei of the degenerated nucel]ar cells. The results indicated that the degeneration of nucellar cells was a progressive and orderly process and supported that the degeneration of nuceilar cells was a programmed cell death.     

Programmed cell death of Pinus nucellus in response to pollen tube penetration

In ovules of Pinus densiflora, pollen tubes elongate and branch into the nucellar tissue in the direction of the female gametophyte. After pollination, nucellar cells located around the pollen grain and tube die off. We showed here that the nuclei of the nucellar cells were stained by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick end labeling). The number of TUNEL-positive cells increased during pollen tube growth. The tips of pollen tube branches protruded into the nucellar cells to form a convex–concave junction. At this junction, the cell membrane of nucellar cells was separated from the cell wall and the protoplast shrank. Small vesicles and amorphous materials were released from the protoplast into the space between the cell membrane and wall. Vacuoles were collapsed, chromatin was condensed, and mitochondria and plastids were deteriorated in the shrunken protoplast. Agarose gel analysis of DNA isolated from the ovules showed a DNA ladder, suggesting that the nuclear DNA had undergone internucleosomal cleavage. These results suggest that nucellar cells undergo programmed cell death in response to pollen tube penetration with some features resembling apoptosis and other features peculiar to nucellar cells. Received: April 13, 2001 / Accepted: December 10, 2001