POSTGENITAL CARPEL FUSION IN CATHARANTHUS ROSEUS (APOCYNACEAE) IV. SIGNIFICANCE OF THE FUSION

The ontogenetic and phylogenetic significances of the postgenital carpel fusion in Catharanthus roseus were investigated experimentally. When one of the two carpel primordia was surgically destroyed prior to carpel fusion, the remaining carpel differentiated nevertheless; however, the tissue development on the adaxial (normally fused) carpel face appeared aberrant. Possible reasons for this modified ontogeny are discussed. The suggestion that syncarpy is phylogenetically significant because any pollen tube can potentially reach any ovule was verified in C. roseus by monitoring pollen tube growth following spatially controlled pollinations. The suture formed by the postgenital fusion was no barrier to pollen tube growth, and the pollen tubes rapidly became distributed throughout the stigmatic tissue.     

REACTIONS OF ALKALOID AND HISTOCHEMICAL INDICATORS IN LATICIFERS AND SPECIALIZED PARENCHYMA CELLS OF CATHARANTHUS ROSEUS (APOCYNACEAE)

Chromic acid, iodine-potassium iodide and Dragendorff reagent were employed to identify reactive cells that may indicate sites of alkaloid accumulation in fresh tissues and latex of C. roseus. Laticifers in all parts of the mature plant and certain parenchyma cells in the cortex and pith regions accumulated reaction products of these alkaloid indicators. These same cells showed primary fluorescence, accumulated vital dyes and lipid indicators in excess of other cells, and exhibited a more intense nadi reaction than other cells. Tests on fresh tissues are interpreted to indicate possible qualitative and quantitative differences in alkaloid content between subterranean and aerial portions of the plant and between mature and immature tissues. These studies showed that reactive products are unevenly distributed in cells and organs of the plant and can be microscopically detected only in laticifers and specialized parenchyma cells.     

LIGHT AND SCANNING ELECTRON MICROSCOPIC INVESTIGATIONS OF SEXUAL REPRODUCTION IN HYDRA CARNEA

In the freshwater hydrozoan Hydra carnea, the egg, matured and grown between the mesoglea and the epitheliomuscular cells of the ectoderm, is extruded after the emission of the second polar body. Surrounded by a clear jelly layer the egg remains attached to the polyp. Sperm which are released from the testicular sacs of male polyps are attracted by the egg. The jelly layer is penetrated only at the site of emission of the polar bodies by sperm which lack a structurally distinct acrosome. One sperm fuses with the egg at that site where the female pronucleus is found to lie close to the egg membrane. After fertilization and cleavage an acellular embryotheca is secreted by the blastomeres. These events were investigated by light and scanning electron microscopy.     

LIGHT AND SCANNING ELECTRON MICROSCOPIC STUDIES ON POLLEN OF TETRAPLASANDRA (ARALIACEAE) AND RELATIVES

Pollen of seven species in Tetraplasandra and three species in related genera were studied with light and scanning electron microscopes. A new thin-section technique was employed for the study of exine stratification and apertural structure. This study reveals several previously undescribed pollen structures for the group. Trends toward increase in pollen size and in specialization of other pollen characters are evident in Tetraplasandra. Pollen of Reynoldsia and Peekeliopanax differs from Tetraplasandra in the pertectate sexine and the absence of inner nexinous breaks, respectively. A pollen correlation study shows that Munroidendron falls readily within the genus Tetraplasandra but is distinguishable from the latter by its bifurcate colpi.     

STEREOLOGICAL ANALYSIS OF ULTRASTRUCTURAL CHANGES DURING INDUCED EPIDERMAL CELL REDIFFERENTIATION IN DEVELOPING FLOWERS OF CATHARANTHUS ROSEUS (APOCYNACEAE)

Stereological principles were used to study epidermal cell redifferentiation during the post-genital tissue union in the developing flowers of Catharanthus roseus. Volume densities of ultrastructural components at three separate stages of cell differentiation were analyzed and compared. Nuclear volume density decreased and vacuolar volume density increased throughout the period studied. The only other components whose volume densities changed significantly were plastids, mitochondria, and dictyosomes. For each of these organelles, the mean relative volume was greatest at the time of fusion. By 12 hr after fusion, however, the mean relative volume of each fell to a level significantly lower than its volume in the prefusion cells.     

紫荆属种子表皮纹饰的扫描电镜观察

报道了七种紫荆属植物的种子表皮的扫描电镜观察结果。根据种皮性状可将紫荆属植物分为两群：第一群仅包含黄山紫荆一种;第二群包含其余的全部种类。     

大鼠海马触液神经元的分布特征及其纤维联系

本文应用ＨＲＰ追踪与电镜结合的方法研究了大白鼠海马接触脑脊液神经元的分布特征和皮质内联系。光镜观察在海马的多形细胞层和锥体细胞层等处可见散在的神经元被标记,而在室管膜层标记的细胞较多,它们分布于交织成网的阳性纤维中。透射电镜可见海马室管膜层的ＨＲＰ反应阳性的神经细胞、树突末稍及神经胶质细胞。在海马室管膜上也见到了被标记的神经纤维。同时在海马室管膜层内还发现未标记的阴性轴突与被ＨＲＰ标记的阳性树突构成的轴－树突触。上述结果提示海马为接触脑脊液神经元存在的部位之一,其接触脑脊液神经元并受到其它神经元的突触调控     

LIGHT AND ELECTRON MICROSCOPIC STUDIES OF THE FUSION CELL IN ASTEROCOLAX GARDNERI SETCH. (RHODOPHYTA,CERAMIALES)12

The fusion cell in Asterocolax gardneri Setch, is a large, multinucleate, irregularly-shaped cell resulting from cytoplasmic fusions of haploid and diploid cells. Subsequent enlargement takes place by incorporating adjacent gonimoblast cells. The resultant cell consists of two parts—a central portion of isolated cytoplasm, surrounded by an electron dense cytoplasmic barrier, and the main component of the fusion cell cytoplasm surrounding the isolated cytoplasm. The fusion cell contains many nuclei, large quantities of floridean starch, endoplasmic reticulum, and vesicles, but few mitochondria, plastids and dictyosomes. The endoplasmic reticulum forms vesicles that apparently secrete large quantities of extracellular mucilage which surrounds the entire carposporophyte. The isolated cytoplasm also is multinucleate but lacks starch and a plasma membrane. Few plastids, ribosomes and mitochondria are found in this cytoplasm. However, numerous endoplasmic reticulum cisternae occur near the cytoplasmic barrier and they appear to secrete material for the barrier. In mature carposporophytes, all organelles in the isolated cytoplasm have degenerated.     

具尾蓝隐藻(CHROOMONAS CAUDATA GEITLER)的研究 Ⅰ形态特征──光镜及扫描电镜观察

对具尾蓝隐藻进行了光学显微镜及扫描电镜的观察。扫描电镜观察证明具尾蓝隐藻具有明显的纵沟,细胞顶端具圆形凹口,表明该种有“口沟”存在。从而澄清了文献上对该种有无“口沟”相互矛盾或模糊不清的描述。     

具尾蓝隐藻(CHROOMONASCAUDATAGEITLER)的研究 Ⅰ形态特征──光镜及扫描电镜观察

对具尾蓝隐藻（Chrcomonascaudata）进行了光学显微镜及扫描电镜的观察。扫描电镜观察证明具尾蓝隐藻具有明显的纵沟,细胞顶端具圆形四口,表明该种有"口沟"存在。从而澄清了文献上对该种有无"口沟"相互矛盾或模糊不清的描述。     

A LIGHT AND ELECTRON MICROSCOPIC STUDY OF PEROXIDASE LOCALIZATION IN THE ONION ROOT TIP

Peroxidase activity in the onion root tip was localized by the diaminobenzidine procedure and studied at the light and electron microscope levels. Reaction product was observed in the cell wall, on the plasmalemma, in the Golgi apparatus cisternae and vesicles, in young and developing vacuoles, in the endoplasmic reticulum, and on both soluble and membrane-bound ribosomes. The reaction product at the various cellular and subcellular sites occurs in distinct tissue and developmental patterns.     

百合离体生殖细胞骨架的扫描电镜观察

从百合的花粉管分离出来的生殖细胞,经表面活化剂Ｔｒｉｔｏｎ Ｘ－１００ 及核糖核酸酶、硫酸铵离析处理。离析后的细胞经临界点干燥,扫描电镜观察显示：在离体生殖细胞的胞质内有一个非常复杂的支架网络系统。这一网络系统有内外两层：外层（靠近细胞膜）网络结构紧密,纤维束粗长;内层（靠近核）网络结构疏松,纤维束短细。一些间接证据显示,这一支架网络系统可能为微管骨架     

A LIGHT AND ELECTRON MICROSCOPIC STUDY OF RHIZOID DEVELOPMENT IN POLYSIPHONIA LANOSA (L.) TANDY1,2

The ontogeny of P. lanosa rhizoids was investigated by light and electron microscopy. A series of distinct, changes was recognized. Prior to penetration of the host, Ascophyllum nodosum, starch reserves were depleted and a large number of dictyosome vesicles accumulated in the cell. These appeared to have been discharged immediately prior to or during host, penetration with a concomitant increase in rhizoid wall thickness. Following initial penetration, the tip became highly convolute and dominated by ER, ribosomes, and mitochondria. Senescence was marked by almost complete, vacuolation of the cytoplasm, degeneration of most organelles, and the loss of color. These ultrastructural changes are correlated wth the habit of P. lanosa.     

扬子鳄鼻腔上皮光学显微镜及扫描电镜观察

本文通过光镜和扫描电镜研究了爬行动物扬子鳄鼻腔上皮的组织学。结果表明:其嗅觉上皮的组成细胞类型与两栖类、鸟类和哺乳类基本相似,但嗅细胞纤毛形状则有所不同;扬子鳄与两栖类、鸟类嗅纤毛相似,呈丝状,而哺乳类嗅觉纤毛则呈棍棒状;据外,扬子鳄鼻腔不同部位可发现不同类型嗅纤毛,鸟兽则无此现象,扬子鳄嗅觉上皮的分布仅局限于鼻腔中部前甲区和鼻甲区狭小范围,而兽类嗅觉上皮一般分布较广;扬子鳄呼吸上皮下未见兽类具有的混合型粘液腺,也未见兽类用以温暖空气的静脉丛,这和扬子鳄属外温动物而兽类为恒温动物密切相关。     

一种游仆虫皮层纤维结构的扫描电镜研究

应用扫描电镜研究了一种游仆虫皮层纤维结构。结果显示,口围带托架由横向组排在一起的小膜托架单元组成,每个小膜托架是由40-50 nm直径的纤维编织成的长方形薄片;波动膜托架是横向平行排列和纵向平行排列两部分共60多股纤维交错编织成的网状结构;额腹横棘毛区表膜下含有纵纤维层、球形纤维层和深部纤维层三层纤维,其纵纤维层在相应于游仆虫皮层脊（或脊和唇）之间的表膜下方被纵沟分成几部分;背面表膜下含有纵纤维,这层纤维下似乎也有球形纤维层。此外,作者也推测了这些皮层纤维结构在游仆虫皮层形态的保持、支持纤毛器和纤毛器运动及形态发生等方面的作用。     

THE GYNOECIAL DEVELOPMENT AND SYSTEMATIC POSITION OF ALLAMANDA (APOCYNACEAE)

Allamanda exhibits an unusual type of gynoecial development in which the two carpels are free at initiation, but fuse completely during development, resulting in a unilocular ovary with parietal placentation at maturity. Whereas the majority of the Apocynaceae are characterized by an advanced type of gynoecium that is secondarily apocarpous, in Allamanda gynoecial evolution has proceeded one step further to secondary syncarpy. This condition is not known to occur in any other genus in the Apocynaceae and provides further evidence of the isolated position of Allamanda within the family.     

具尾蓝隐藻(CHROOMONAS CAUDATA GEITLER)的研究 Ⅰ形态特征──光镜及扫描电镜观察

对具尾蓝隐藻(Chrcomonas caudata)进行了光学显微镜及扫描电镜的观察。扫描电镜观察证明具尾蓝隐藻具有明显的纵沟,细胞顶端具圆形四口,表明该种有"口沟"存在。从而澄清了文献上对该种有无"口沟"相互矛盾或模糊不清的描述。     

A SCANNING ELECTRON MICROSCOPIC STUDY ON THE INITIATION AND DEVELOPMENT OF FLORAL ORGANS OF BRASSICA NAPUS (CV. WESTAR)

The initiation and development of the floral organs of Brassica napus L. (cv. Westar) were examined using the scanning electron microscope. After transition of the vegetative apex into an inflorescence apex, flower primordia were initiated in a helical phyllotactic pattern. The sequence of initiation of the floral organs in a flower bud was that of sepals, stamens, petals and gynoecium. Of the four sepal primordia, the abaxial was initiated first, followed by the two lateral and finally the adaxial primordium. The four long stamens were initiated simultaneously in positions alternating with the sepals. The two short stamens were initiated basipetal to and outside the long stamens, and opposite the lateral sepals. The petals arose on either side of the two short stamens and the gynoecium was produced from the remainder of the apex. During development, the sepal primordia curved sharply at the tips and tightly enclosed the other organs. Stamen primordia developed tetralobed anthers at an early stage while filament elongation occurred just prior to anthesis. A unique pattern of bulbous cells was present on the abaxial surface of the anther. Growth of petal primordia lagged relative to the other floral organs but expansion was rapid prior to anthesis. The gynoecium primordium was characterized by an invagination early in development. At maturity, there was differentiation of a papillate stigma, an elongated style and a long ovary marked externally by sutures and divided internally by a septum. Distinct patterns of cuticular thickenings were observed on the abaxial and adaxial surfaces of the petals and stamens and on the surface of the style. The patterns were less obvious on the sepals and ovary. Stomata were present on both surfaces of the mature sepals, on the style and restricted areas on the abaxial surface of the anthers and nectaries but were absent from the petals, the adaxial surface of the stamens and the ovary. No hairs were present on any of the floral organs.     

重复热处理对大鼠精子发生的影响研究:光学和电子显微镜观察

大鼠睾丸每月重复接受43℃热处理(每次处理25分钟)。第一次加温后24小时,光学和电镜观察指出,生殖细胞对加热反应并非是一种特异性效应。电镜观察指出,所有发育期的生殖细胞的胞核均受损伤,但其他细胞器,如细胞膜和线粒体却很完整。本实验表明,加热原初损伤是细胞核,而不是胞质的膜系统。 首次加温后24小时,具空泡化胞核的早期精细胞已有一个小顶体,而胞质的特征却相似于分裂的精母细胞。表明加热能引起精母细胞的核——质非同步发育,即加速胞核分裂和分化。 每月一次,二次加温后182天,绝大多数精小管内无生殖细胞,但在一些部分恢复的精细管中,还发现空泡化的多核巨细胞,本结果表明,一些休止期精原细胞也受潜在损伤,并能生存相当长时间;一旦细胞进行分裂之后,就出现退行性交。