北柴胡大小孢子发生和雌雄配子体发育的研究

用石蜡切片法对北柴胡的大、小孢子发生和雌、雄配子体发育过程进行观察研究.结果显示,北柴胡的胚珠为倒生型,单珠被,薄珠心.孢原细胞不经分裂直接发育成大孢子母细胞;四分体线性,多数情况下合点端的大孢子为功能大孢子,少数情况下亚合点端的大孢子也可发育为功能大孢子,蓼型胚囊;八核胚囊时期,珠心基部和两侧的一些珠心细胞保持自己的细胞质和形状,留存较久,成为珠心座细胞,珠被内表皮细胞发育为珠被绒毡层;花药壁发育类型为基本型,绒毡层为腺质绒毡层.小孢子母细胞减数分裂的胞质分裂为同时型,产生正四面体型四分体.成熟花粉为3细胞型.     

矮沙冬青雌配子体及胚胎发育研究

矮沙冬青子房单心皮1室,边缘胎座,弯生胚珠,胚珠具双珠被、厚珠心。大孢子孢原细胞发生于珠心表皮下,大孢子母细胞减数分裂形成直线排列的四分体,合点端大孢子具功能,并按蓼型胚囊发育,雌配子体成熟于4月中旬。双受精后,胚乳发育为核型。在矮沙冬青大孢子发生、雌配子体和胚胎发育过程中未发现异常现象,因此认为矮沙冬青濒危不存在雌性生殖结构与发育过程异常的内在因素。     

八角莲大孢子发生和雌配子体形成

首次报道了八角莲(Dysosma versipellis (Hance)M.cheng)大孢子发生和雌配子体形成的过程.结果:双珠被,多为厚珠心胚珠,少数为假厚珠心,胚珠多为横生,少数为弯生;边缘胎座,子房一室,多胚珠,珠孔由两层珠被共同形成,呈"之"字形;多为单孢原,位于珠心表皮下:偶见2～3个孢原细胞位于珠心表皮下;大孢子母细胞有两种发生方式;直线形大孢子四分体,合点端的大孢子发育为功能大孢子,蓼型胚囊;成熟胚囊中,二个极核在受精前合并为次生核;三个反足细胞不发达,较早退化;"品"字形卵器极性明显,其中卵细胞与助细胞极性相反;助细胞发达,其丝状器在不同发育时期形态及大小不同,且具吸器功能.     

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。     

小盐芥大孢子发生和雌配子体发育

本论文研究了小盐芥（Thellungiella halophila）大孢子发生和雌配子体发育过程及该阶段与花蕾、花、果实外部形态的相关性。结果如下：小盐芥雌蕊由2心皮组成,侧膜胎座,每室胚珠多数,弯生,双珠被,薄珠心。孢原细胞位于珠心表皮之下,直接起大孢子母细胞的功能。大孢子四分体线形排列,合点端大孢子为功能大孢子,胚囊发育为蓼型。     

小盐芥大孢子发生和雌配子体发育

本论文研究了小盐芥(Thellungiella halophila)大孢子发生和雌配子体发育过程及该阶段与花蕾、花、果实外部形态的相关性。结果如下: 小盐芥雌蕊由2心皮组成, 侧膜胎座, 每室胚珠多数, 弯生, 双珠被, 薄珠心。孢原细胞位于珠心表皮之下, 直接起大孢子母细胞的功能。大孢子四分体线形排列, 合点端大孢子为功能大孢子, 胚囊发育为蓼型。     

黄顶菊的大孢子发生、雌配子体与胚胎发育

用常规石蜡制片对黄顶菊(Flaveria bidentis(L.) Kuntze)大孢子发生、雌配子体和胚胎的发育过程进行了观察.黄顶菊雌蕊柱头二裂,2心皮,1室,单胚珠,基生胎座,单珠被,薄珠心,倒生胚珠,具发达的珠被绒毡层.珠心表皮下分化出孢原细胞,孢原细胞直接发育为大孢子母细胞,大孢子母细胞减数分裂形成直列四分体...     

观光木的大孢子发生与雌配子体形成

对观光木（Tsoongiodendron odorum Chun)的大孢子发生,雌配子体形成过程的观察结果显示,观光木子房单心皮,心皮腹面壁上着生2-5个胚珠;胚珠倒生型,厚珠心,两层珠被;孢原细胞一个,并且自表皮下1-2层处分化。胚囊发育为蓼型。在四分体和成熟胚囊时期观察到了异常发育现象。初步探讨了观光木濒危的生殖生物学原因。     

粉叶小檗大孢子发生和雌配子体形成

采用石蜡切片方法对粉叶小檗（Berberis pruinosa Franch.)的大孢子发生和雌配子体形成过程进行了研究。主要结果如下：雌蕊1枚,子房单心皮,边缘胎座,2枚胚珠倒生,具双珠被,厚珠心,珠孔由内外两层珠被共同形成,呈“Z”字形;单孢原,位于珠心表皮下;直线形大孢子四分体,合点端的1个大孢子发育为功能大孢子,胚囊发育类型为蓼型;成熟胚囊中,2个极核在受精前融合为次生核;3个反足细胞不发达,较早退化;"品"字形卵器,其中助细胞发达且具丝状器。     

宁夏枸杞大孢子发生和雌配子体发育的细胞学研究

采用半薄切片技术和组织化学染色法对宁夏枸杞大孢子发生和雌配子体发育过程中的细胞结构变化及营养物质积累特征进行了观察。结果表明,(1)宁夏枸杞为中轴胎座,多室子房,倒生胚珠,单珠被,薄珠心类型。(2)位于珠心表皮下的孢原细胞可直接发育为大孢子母细胞,减数分裂后形成直线型大孢子四分体,合点端第一个大孢子发育为功能大孢子,胚囊发育类型为蓼型,具有珠被绒毡层。(3)初形成的胚囊外周组织中没有营养物质积累,成熟胚囊时期出现了大量的淀粉粒且呈珠孔端明显多于合点端的极性分布特征。(4)助细胞的珠孔端具有明显的丝状器结构,呈PAS正反应表现出多糖性质,成熟胚囊具有承珠盘结构。     

Translocation of Uranin within the Living Ovules of Vanilla

In the ovules of Vanilla (Vanilla planifolia Andr.) before fertilization, outer integument surrounded the lower part of ovule. Uranin got into ovule through funiculus, forming, the first center of fluorescence at the chalaza zone of ovule. Then uranin was transported to micropyle end along inner integument, forming the second center of fluorescence at micropyle end of inner integument. Soon, fluorescence appeared in the egg apparatua. After fertilization, the outer integument ovule extended upward, forming micropyle ogerber with inner integument. After getting into ovule through funiculus, uranin spreads to- ward several directions: l. transported to outer integument at the entrance of micropyle; 2. transported downward to chalaza zone along outer integument at the side of funiculus; 3. extended from chalaza zone to the inside and to the outer integument at the side far from funiculus The ovules of Vanilla had no vascular bundles. On transporting in inner integument, however, the cells in inner layer next to the embryo sac appeared to be the major passage. In mature embryo sac, there was cuticle between inner integument and embryo sac at the half of micropyle end. But between embryo sac at the half of chalaza end and nucellus, cuticle was absent. Nutrient could get into embryo sac from chalaza end undoubtedly. As egg apparatus showed the fluorescence after formation of fluorescence center of inner integument at micropylar end, the possibility that nutrient got into embryo sac from micropyle could not be excluded.     

The phenotype of Arabidopsis ovule mutants mimics the morphology of primitive seed plants

In seed plants, the ovule is the female reproductive structure, which surrounds and nourishes the gametophyte and embryo. This investigation describes the PRETTY FEW SEEDS2 (PFS2) locus, which regulates ovule patterning. The pfs2 mutant exhibited developmental defects in the maternal integuments and gametophyte. This mutation was inherited as a maternal trait, indicating that gametophyte defects resulted from ovule patterning aberrations. Specifically, the boundary between the chalaza and the nucellus, two regions of the ovule primordia, shifted towards the distal end of pfs2 ovule primordia. Results indicated that the PFS2 locus could: (i) be involved in the development of either the nucellus or the chalaza; or (ii) establish a boundary between these two regions. Examination of genetic interactions of the pfs2 mutation with other well-characterized ovule loci indicates that this locus affects integument morphogenesis. Interestingly, the pfs2 inner no outer and pfs2 strubbelig double mutants had inner integuments that appeared similar to their ancestral precursor. The fossil record indicates that the inner integument evolved by fusion of sterilized sporangia or branches around a central megasporangium. The question of whether the structures observed in these double mutants are homologous or merely analogous to the ancestral precursors of the inner integument is discussed.     

A structural investigation of the ovule in sugar beet, Beta vulgaris: Integuments and micropyle

The micropyle and the integuments of sugar beet (Beta vulgaris) ovules have been investigated by light and electron microscopy during differentiation and maturation of the ovule. The micropyle itself is formed by the inner integument which is surrounded by the outer integument at its base. The micropyle containts a fibrillar PAS+ substance and is often covered by a thin sheet or hymen. Both integuments are cuticle-covered thin sheets, each 2-few cell layers in thickness. In the outer integument an increase in starch accumulation occurs during ovule maturation and probably functions as nutrient storage for embryo development. The inner epidermis of the inner integument differentiates as the most conspicuous cell layer of the beet ovule. During growth and maturation of the ovule a system of small perinuclear vacuoles containing dense material increases steadily in these cells. At maturity this system fills up more than half of each cell and very dense material has accumulated in each vacuole. This vacuole content is highly refractive and contains tannins and/or polyphenols.     

Gone and ovule ontogeny in Phyllocladus (Podocarpaceae)

TOMLINSON, P. B., TAKASO, T. & RATTENBURY, J. A., 1989. Cone and ovule ontogeny in Phyllocladus (Podocarpaceae). Cones are borne directly on phylloclades, usually in the position of basal segments or as segment appendages. Each cone consists of a series of spirally arranged bracts, of which the middle bracts each subtend a single, sessile ovule. There is no ovuliferous scale. Ovules arise as ovoid outgrowths; integument development involves periclinal divisions of hypodermal cells with the integument becoming bilobed and extended laterally. The mature ovule is flask-shaped. The integument includes an extensive middle region bounded by an inner and outer epidermis; the outer hypodermis is differentiated as two contrasted cell layers. An aril differentiates late by periclinal divisions of the outer hypodermal cells at the base of the ovule. The three outermost layers of the integument become differentiated in the mature seed as an epidermis, with thick, cutinized outer tangential walls, an outer hypodermal tanniniferous layer and a sclerotic inner layer. Each ovule is vascularized by two strands that diverge from the axial bundles delimiting the gap left by the departing bract trace.     

Interactions among Genes Regulating Ovule Development in Arabidopsis Thaliana

The INNER NO OUTER (INO) and AINTEGUMENTA (ANT) genes are essential for ovule integument development in Arabidopsis thaliana. Ovules of ino mutants initiate two integument primordia, but the outer integument primordium forms on the opposite side of the ovule from the normal location and undergoes no further development. The inner integument appears to develop normally, resulting in erect, unitegmic ovules that resemble those of gymnosperms. ino plants are partially fertile and produce seeds with altered surface topography, demonstrating a lineage dependence in development of the testa. ant mutations affect initiation of both integuments. The strongest of five new ant alleles we have isolated produces ovules that lack integuments and fail to complete megasporogenesis. ant mutations also affect flower development, resulting in narrow petals and the absence of one or both lateral stamens. Characterization of double mutants between ant, ino and other mutations affecting ovule development has enabled the construction of a model for genetic control of ovule development. This model proposes parallel independent regulatory pathways for a number of aspects of this process, a dependence on the presence of an inner integument for development of the embryo sac, and the existence of additional genes regulating ovule development.     

Ovular development and morphology in some magnoliaceae species

Floral phenology and ovular development ofLiriodendron tulipifera are described. The ovule primordia are initiated in December, followed by prominent development in March, and the ovules are mature in May. The inner integument is formed as an annular rim on the incurving ovule primordia, but the outer integument develops as a semi-annular rim interrupted on the concave side of the funicle. Later, an outgrowth, which is interpreted here as an obturator, arises on the concave side of the funicle. The funicular outgrowth arises far from the inner integument, while the outer integument is close to the inner. The outer integument and the funicular outgrowth together form an envelope complex. Later the outer integument produces two distal lobes, which disappear at maturity. Mature ovules of the threeMagnolia species examined have similar lobes. It is suggested that the hood-shaped outer integument is primitive in angiosperms.     

<Emphasis Type="Italic">Gypsy embryo</Emphasis> specifies ovule curvature by regulating ovule/integument development in rice

The embryo position in a seed is stable in most plant species, indicating the existence of a strict regulatory mechanism that specifies the embryo position in the seed. To elucidate this mechanism, we analyzed the gypsy embryo (gym) mutant of rice, in which the position of the mature embryo in the seed is altered at a low frequency. Analyses of early embryogenesis and ovule development showed that the ectopic embryo was derived from an ill-positioned egg cell, which resulted from the incomplete curvature of the ovule. Although the development of both the inner and outer integuments was impaired, the ovule curvature was associated closely with the extent of inner integument growth. Therefore, inner integument development controls ovule curvature in rice. The expression patterns of OSH1 and OsMADS13 indicated that, in gym, a small number of indeterminate cells are maintained on the style side of the ovule and then in the integument primordium at a low frequency. The prolonged survival of these indeterminate cells disturbs normal integument development. The gym fon2 double mutant suggests that GYM and FON2 are involved redundantly in floral meristem determinacy. Possible functions of the GYM gene and the ovule developmental mechanism are discussed.     

Comparative embryology of Bambusa tulda Roxb. and Thyrsostachys siamensis Gamble (Poaceae: Bambuseae)

Bambusa tulda and Thyrsostachys siamensis resemble each other in having an obovate ovary which is hairy and thickened along the apex, a pseudo-crassinucellate ovule with a wide region of attachment, poorly-developed and ephemeral outer integument, an inner integument which fails to grow beyond the nucellus, 'Polygonum' type of embryo sac ontogeny, parallel orientation of embryo sac to the long axis of the ovule, multiple antipodals which retain apical position in the embryo sac even during post-fertilization phase of development, an ephemeral nucellus, relatively small bambusoid embryos, and many-layered and apically thickened pericarp. However, they differ from each other in their gynoecial structure, the extent of the development of the outer integument, organization of megaspore tetrads and development-stage-related behaviour of the inner integument in the fertilized ovules. These taxa also differ from other members of the subfamily Bambusoideae in the structure of the mature ovule, endosperm and pericarp.     

Embryogenesis and seed development in Sinomanglietia glauca (Magnoliaceae)

The development of the floral bud, especially the ovule and seed coat, of Sinomanglietia glauca was observed. Floral buds were covered by eight to nine hypsophyll pieces. The hypsophyll nearest the tepal was closed completely and characterized by two arrays of densely stained cells with dense cytoplasm, which split longitudinally at flowering. The perianth consisted of 16 tepals arranged in three whorls. The gynoecium was composed of numerous apocarpous carpels; the ovule was anatropous with two integuments. Embryogenesis was of the Polygonum type, and the endosperm was nuclear. The inner integument degenerated during seed development. The seed of S. glauca had an endotestal seed coat comprised of a sclerotic layer derived from the inner adaxial epidermis of the outer integument and a sarcotesta derived mainly from the middle cells between the inner and outer epidermis of the outer integument. The embryo developed normally, so embryogenesis is not the cause of difficult regeneration.     

Ovule morphogenesis and structure in Menispermaceae,focusing on the development of the single fertile ovule and its systematic significance

Menispermaceae is one of the core groups of Ranunculales. The single fertile ovule in each ovary in Menispermaceae varies greatly in integument number, micropyle formation, and integument lobe. However, data regarding ovule morphogenesis in the family are very limited. In this study, we document ovule development of selected species in the Menispermaceae using scanning electron microscopy and light microscopy. Ovule development in Menispermaceae shows the following characteristics. Two ovules are initiated in a young carpel, one of them degenerates gradually and the other develops into a fertile ovule in subsequent stages. Bitegmic in Sinomenium Diels. and Cocculus DC. and unitegmic in Stephania Lour. The formation of unitegmy is probably due to integumentary shifting. The annularly initiated inner integument is of dermal origin and has 2–3 cell layers in the family, but the semi-annularly initiated outer integument is of both dermal and subdermal origin. Both inner and outer integument are cup-shaped at maturity. The cup-shaped outer integument is formed due to the outer integument's extension to the concave (adaxial) side of the funiculus. The obturator is well developed and consists of 2–3 cell layers in Cocculus or 9–11 cell layers in Stephania. Ovule development of Menispermaceae suggests some common characteristics between Cocculus and Sinomenium, and derived unitegmy supports molecular data that indicate Stephania is one of the late-diverging lineages in the family. Integument lobations are present. The sterile ovule shows variations in the degeneration process. These results will provide evidence for exploring the evolution of ovules in Ranunculales.