WOOD ANATOMY AND RELATIONSHIPS OF LACTORIDACEAE

Mature wood of Lactoris, not previously available for study, reveals ten distinctive characters: vessels with simple perforation plates; vessels in pore multiples; vessel-to-axial parenchyma pits scalariform or transitional, vessel-to-vessel pits alternate; fiber-tracheids with vestigial pits; fiber-tracheids, vessels, and axial parenchyma storied; axial parenchyma vasicentric scanty; axial parenchyma either not subdivided or, if subdivided, with thin nonlignified walls between the cells (like the septa in septate fibers); rays wide and tall, little altered during ontogeny; ray cells upright; and ray cells taller adjacent to fascicular areas. All of these features occur in woods of Piper and other Piperaceae. The systematic position of Lactoris is therefore reassessed. Evidence available to date is consonant with placement of Lactoridaceae in Piperales, in which it would be more primitive than Piperaceae or Saururaceae. Features cited as evidence for alternative placements of Lactoridaceae are reviewed.     

星叶草属的核形态及其系统位置

本文研究了星叶草属的核形态。其间期核和前期染色体分别为简单染色中心型和中间型;中期染色体较小,长度介于3.00μm到1.20μm之间;核型公式为2n=30=22m+8sm。其明显很高的染色体基数以及其它退化和特化的形态学性状,表明该属是一个孑遗的古多倍体类群。该属与独叶草属在间期核形态、前期染色体形态以及中期染色体的大小和形态方面极为相似。结合其它方面的资料,本文认为星叶草属和独叶草属有较近的亲缘关系,支持将它们一起置于星叶草科的观点。     

裸蒴属的核型及三白草科四属间系统关系的探讨

本文首次报道三白草科裸蒴属中华裸蒴(Gymnotheca chinensis Decne)和白苞裸蒴(G. involucrata Pei)的染色体数目。两个种的体细胞染色体数均为2n=18,染色体基数为x=9。三白草科原始祖先的染色体基数假定为x=11,裸蒴属可能是经非整倍减少演变而来。裸蒴属间期核型属球状或棒状前染色体型。本文根据三白草科染色体研究的结果和现代地理分布格局,结合其他分枝学科的研究资料,对科下四属间的系统发育关系提出了初步假设。     

白刺属的胚胎学特征及其系统学意义

作者在对白刺属的胚胎学进行了详细研究的基础上,比较了该属与蒺藜科内Fagonia,seetzenia,zygophyllum,pegamum,Balanites等属的胚胎学特征,发现白刺属在花药壁的发育、小孢子四分体排列,雌蕊的结构、胚珠的数目、珠心的发育、珠被绒毡层有无、珠孔的构成、大孢子孢原和大孢子母细胞的数目、胚柄的发育、多胚现象、果实的发育和类型等方面存在明显的差异。结果表明胚胎学特征支持将白刺属独立为白刺科的观点。文中对蔟藜科胚胎学及系统学研究作了结论。     

EMBRYOLOGY AND DEVELOPMENT OF THE ENDOSPERM HAUSTORIUM OF ARCEUTHOBIUM DOUGLASII

Arceuthobium douglasii develops a dome-like structure, the ovarian papilla, in which 2 megasporocytes are formed. The papilla is not a true ovule, for no integuments are formed, and it is forced aside by the developing endosperm. Megasporocytes are differentiated in the spring, but meiosis does not occur until the following spring. A tetrasporic embryo sac is developed which is 8-nucleate at maturity. Pollination and fertilization occur approximately 13–14 months after initiation of the inflorescence. Only 1 of the 2 embryos develops after fertilization. After fertilization, the embryo sac segregates into 2 parts, one containing the zygote and the disintegrating synergids, the other the primary endosperm nucleus and the degenerating antipodals. This primary endosperm cell elongates toward the base of the ovarian papilla. Cytokinesis then forms an endosperm cell, adjacent to the zygote, and a haustorial cell. The haustorial cell forms several tiers of cells which persist during the development of the embryo and endosperm. The zygote, while still contained within the ovarian papilla, divides, forming a 2-celled sphere. It remains unchanged until after it is conveyed out of the ovarian papilla by the developing endosperm. The development of the embryo and endosperm is arrested in the autumn approximately 3 months after their initiation. They complete their development the following spring and summer.     

EMBRYOLOGY AND SYSTEMATIC POSITION OF HETEROPYXIS (MYRTALES)

We present here the first study of the embryology of Heteropyxis, in order to evaluate its relationships with Myrtaceae, a family in which it has often been placed. On the basis of embryology, Heteropyxis is undoubtedly very closely allied to Myrtaceae, but is distinct in possessing 1) a bisporic Allium type embryo sac, 2) a condition in which the two microsporangia of the theca are remotely separate from each other and dehisce by their respective longitudinal slits instead of by a common slit, and 3) an ovule and seed that has wings on both ends. All of these embryological characteristics are apomorphic features; they contrast with many other characteristics of the genus, such as its completely superior ovary and separate staminal traces, which are clearly primitive ones. Like the unique monotypic Psiloxylon, an endemic of Mauritius, Heteropyxis clearly diverged early from the evolutionary line leading to Myrtaceae before the origin of the common ancestor of that family (excluding Heteropyxis and Psiloxylon). Heteropyxis could logically be regarded either as a subfamily of Myrtaceae distinct from all other members of the family or as a separate but related family. We shall return to this question when our review of the embryological features of Psiloxylon has been completed.     

款冬属的核形态(菊科:千里光族)

研究了款冬属的核形态。染色体间期为简单型与复杂型的过渡型;前期染色体为近基型与中间型的过渡型。染色体较小,核型不对称,具明显的二型性;数目与核型公式为2n=60=42m+10sm+6st+2t。比较发现款冬的核型明显不同于千里光族中已有的核型记载,其核型特征似乎与它独特的形态特征相联系,具有重要的系统学意义。     

MORPHOLOGY,VASCULAR ANATOMY AND EMBRYOLOGY OF PISTILLATE AND STAMINATE FLOWERS OF ASPARAGUS OFFICINALIS

Flowers of three pistillate (female), two heterogametic staminate (male) and two homogametic male genotypes of Asparagus officinalis L. were compared for morphology and vascular anatomy of the flower and for embryological development to the stage of mature ovules and pollen. Flowers are liliaceous, the staminate with rudimentary pistils and the pistillate with collapsed anthers. The uncomplicated vascular pattern differs between staminate and pistillate flowers only in the size and degree of maturation of bundles to stamens and carpels. Longer styles appear to be correlated with a greater extent of ovule development in ovaries of staminate flowers. Microsporogenesis in males is normal with wall development corresponding to the Monocotyledonous type. The tapetum is glandular and binucleate, cytokinesis successive, the tetrads isobilateral or occasionally decussate, and the mature pollen grain two-celled. A pair of heteromorphic, possibly sex, chromosomes was observed in heterogametic male plants. Anther development is initially the same in pistillate flowers, but the tapetum degenerates precociously followed by collapse of microspore mother cells. In pistillate flowers the ovules are hemitropous, bitegmic, and slightly crassinucellate. Megasporogenesis-megagametogenesis conforms to the Polygonum type. In staminate flowers ovule development is like that in pistillate flowers until degeneration starts in nucellar and integumentary cells at the chalazal end. Ovules in both homogametic male genotypes rarely complete meiosis, while in the heterogametic males it is normally completed with about one ovule in 20 flowers forming a mature megagametophyte. Since manipulation of sex expression in Asparagus could be important in developing inbred male and female lines for breeding purposes, those aspects of the morphological and embryological observations presented which might be useful in planning experiments to induce sex changes are discussed briefly.     

留学生组织学与胚胎学教学特点与经验

我室已承担留学生组织学与胚胎学教学7届,在课程内容设置和时间安排、教材选用、任课教师遴选、教学方法和教学手段以及考试与成绩评定方面积累了一些经验,了解了留学生教学的特点,同时在教学中仍然存在一些不足。需要在实践中不断找出存在的问题并及时解决,使留学生教学质量稳步上升。     

组织学与胚胎学全英语教学实践

顺应医学教育国际化趋势,我们进行组织学与胚胎学全英文教学实践活动已有八年。作为一门医学基础课程,组织学与胚胎学全英文教学改革之初也遇到教材、师资、授课方法等诸多困难,通过学校的政策扶持以及教研室全体教师的努力,目前组织学与胚胎学全英文课程教学体系已日趋完善、成熟,在教学内容、教学方法、教材编写、师资建设等方面取得了长足的进步,为医学生进行后续全英文课程的学习打下坚实的基础。     

强化实验教学管理 提高组织学与胚胎学实验教学效果

组织学与胚胎学（组胚）是医学教育重要的基础课程。随着医学教育改革的深入发展,我们通过适时调整实验教学大纲,在科室合作、教师培养、集体备课、多媒体教学、开放实验室、和实验教学档案管理等方面加强了对实验教学的管理,以提高组胚实验教学效果。     

RIBOSOMAL DNA AND RAPD VARIATION IN THE RARE PLANT FAMILY LACTORIDACEAE

Lactoris fernandeziana, endemic to the island of Masatierra in the Juan Fernandez Archipelago, is the only living member of the primitive angiosperm family, Lactoridaceae. The species was surveyed for ribosomal DNA (rDNA) and RAPD (Random Amplified Polymorphic DNA) variation. Previous analyses of allozymes had revealed no variation within the species. Variation was found for length in the intergenic spacer and for restriction sites in the 18S–25S genes of rDNA, and for the presence of amplified bands using 16 primers. Different rDNA repeat lengths and restriction site variants were detected within individuals as well as within and among populations. The level of variation in RAPDs is low relative to other Juan Fernandez endemic species surveyed, and nearly all variants were restricted to single populations. The rDNA length variants were distributed throughout the island, whereas the rDNA restriction site variants and RAPD markers indicated minor genetic differences among the populations.     

组织学与胚胎学双语教学教学模式探索

为顺应时代发展的需要,改善教学质量,提高医学生专业外语水平,我们在五年制中有选择的进行了多年的组织学与胚胎学双语教学改革。本文就授课对象的选择、教材的选用、教学方法、考核方法、教学效果分析和出现的问题及对策等方面进行了分析和小结。旨在总结经验,并不断的改进和完善双语教学。     

红直獐牙菜的胚胎学

首次报道了红直獐牙菜大小孢子发生,雌雄配子体形成和胚胎发育过程。主要结果如下：花药四室,药壁发育为双子叶型,绒毡层异型起源,接近腺质绒毡层,中层３层,花药壁表皮宿存,细胞柱状伸长,纤维状加厚,药室内壁退化,小孢子母细胞减数分裂为同时型,四分体的排列方式为四面体形;成熟花粉为３－细胞;子房２心皮,１室,１２列胚珠,侧膜胎座,薄珠心,单珠被,倒生胚珠,蓼型胚囊,反足细胞３个,宿存时间短,胚乳发育为核型     

蒙古黄芪的胚胎学

蒙古黄芪(Astragaius monghocus Bge.)雄性原为花药表皮下单列细胞,小孢子四分体为四面体型,胞质分裂为同时型。单子叶型花药壁。分泌型绒毡层,其细胞核始终一个,细胞里含有一至多个草酸钙晶体。二细胞型花粉:单室子房,多胚珠,弯生,双珠被,厚珠心。蓼型胚囊。雌性孢原为珠心亚表皮下多细胞。直线形大孢子四分体,合点端第一、或第二、或第三个大孢子有功能。成熟胚囊具有盲囊结构;花粉管通过退化助细胞进入胚囊。双受精属于有丝分裂前配子融合类型;胚的发育为柳叶菜型。核型胚乳。胚乳细胞在球形胚时期开始形成。在胚乳发育过程中,合点端胚乳游离核存在着聚集、合并、无丝分裂和胚乳细胞内多核合并等现象。