Schistosoma mansoni: Drug induced changes in the cell population of the vitelline gland

Using the electron microscope four stages in the development of the mature vitelline cell in normal Schistosoma mansoni have been defined precisely and the percentage of their contribution to the cell population of the vitelline lobule has been determined. The effects of Astiban, Lucanthone, and Hycanthone on this cell population were examined and compared with the composition of the normal vitelline lobule. Astiban damaged mature cells and those stages exhibiting protein synthesis. Undifferentiated, nonsynthetic cells did not exhibit morphological damage and rapidly developed and replenished the vitelline lobule so that a normal population was attained within a few days after cessation of drug treatment. In contrast, Lucanthone and Hycanthone appeared to inhibit the division of these undifferentiated cells so that they gradually disappeared from the lobule. The various developmental stages and mature cells which had arisen from these undifferentiated cells accumulated in the lobule, but were eventually damaged. With both these drugs, the lobule population eventually came to consist largely of mature cells. In the case of Hycanthone, it is suggested that the retention of these stages within the lobule was due to interference with the neuromuscular system so that the cells were not passed down the vitelline duct. Withdrawal of Lucanthone and Hycanthone did not result in the replenishment of the vitelline lobule. With all drugs used, cell death was associated with vacuolation, the appearance of myelin configuration, disruption of vitelline droplets, an increase in the lipid content of cells, and an increase in the density of the cytoplasm. The experiments indicate that these three drugs produced a differential cell death in the vitelline lobule, the precise changes in the cell population being dependant on the particular drug being used.     

Schistosoma haematobium: the effect of Astiban on the cell composition and ultrastructure of the vitelline gland and the ultrastructure of the tegument and gastrodermis

Treatment of Schistosoma haematobium (Nigerian strain) in hamsters with a single dose of 40 mg/kg of Astiban caused a reduction in the number of S1, S2, and S3 vitelline cells and an increase in S4 cells. Following seven daily doses of the drug, a marked reduction in S1 cells and a complete loss of S2 and S3 cells occurred such that 95% of the cells were S4 cells, all of which were structurally abnormal. Coagulation and disintegration of the protein granules of the vitelline droplets occurred with increase in lipid droplets, swelling of the nuclear membrane and an increase in cytosegresomes. Blebbing of the tegument in both sexes occurred following a single treatment and vacuolation of the basal infolds and alterations to the mitochondria also resulted, but severe erosion of the tegument was rare even following repeated drug treatment. Damage to the gastrodermis was severe with the development of autophagic vacuoles containing whorls of myelin and sequestered portions of damaged tissue. The degree of damage increased with the number of drug treatments.     

Schistosoma haematobium: Amoscanate and adult worm ultrastructure

Amoscanate, when administered orally as an aqueous or “formulated” preparation, induced pronounced ultrastructural abnormalities in male and female Schistosoma haematobium. Higher dose levels of the aqueous suspension (300 mg/kg body wt) had to be administered to achieve the full range of effects induced by formulated doses of 2.5–8 mg/kg body wt. Worms were recovered from hamsters between 1 and 120 hr after treatment. Although the amount of amoscanate-induced damage varied considerably between worms, an overall pattern of damage emerged. Initially, 1 hr after treatment, amoscanate caused tegumental vacuolation and oedema. As the drug treatment period was extended to 24 hr, blebbing, exudation, collapse of sensory organelle bases, and abnormal mitochondria became increasingly evident. With exposure to higher drug doses (50–300 mg/kg body wt), the tegument became further distorted with the appearance of necrotic structures and myelin whorls, which appeared to represent various stages in lysosomal formation and digestion. Eventually, erosion of surface layers resulted in the breakdown of tegumental integrity. The caeca and vitellaria were also adversely affected by drug treatment. Basal vacuolation and the formation of myelin whorls occurred in the gastrodermis. In the mature S4 vitelline cells, coalesced vitelline droplets and myelin whorls were evident.     

日本血吸虫卵黄培养细胞超微结构动态的研究

从超微结构水平研究日本血吸虫卵黄细胞培养的动态。在体外培养过程中,卵黄细胞对外界环境的改变比日本血吸虫的其它体细胞更加敏感。随着培养时间的延长,卵黄细胞发生不同程度的变性,成熟卵黄细胞比未成熟卵黄细胞发生变性。变性主要表现在核和胞质的电子密度降低;卵黄球相互融合,或卵黄球与膜之间的空隙逐步增大,最终卵黄球从中释放出来,变成裸露体;脂滴数目增多,体积增大;粗面内质网扩大和囊泡变,其上的核糖体脱颗粒等     

Helper Function of Follicle Cells in Sperm-Egg Interactions of the Ascidian, Ciona intestinalis

Studies were made on the involvement in sperm-egg interactions of follicle cells of Ciona intestinalis , which are tall, vacuolated cells attached to the outer surface of the egg vitelline coat. The basal surface of the follicle cells is polygonal. The borders between cells could easily be observed by the binding of fluorescent SBA (soy bean agglutinin), a lectin recognizing N-acetylgalactosamine (GaINAc) residues. At fertilization many spermatozoa aggregate along these polygonal borders of cells on the vitelline coat, through which they entered the perivitelline space. The removal of follicle cells was sometimes associated with loss of SBA-binding sites, and in such cases the sperm did not show a hexagonal pattern of aggregation, but became dispersed all over the vitelline coat. Removal of the follicle sometimes delayed fertilization. Examination of sections of gametes stained with DAPI, a fluorescent dye staining DNA, showed that removal of the follicle reduced the number of spermatozoa bound to the vitelline coat and, more especially, the number of spermatozoa penetrating through the vitelline coat. The blockage of GalNAc residues on the vitelline coat with SBA did not appreciably affect the time course of fertilization or the number of sperm associated with eggs. These findings are discussed in relation to the role of follicle cells in facilitating sperm aggregation on the vitelline coat and their penetration through it.     

Origin and Differentiation of the Inner Follicular Cells during Oogenesis in Molgula pacifica (Urochordata), an Ascidian without Test Cells

In Molgula pacifica small previtellogenic oocytes are found between cells of the ovarian epithelium. Each oocyte subsequently grows within a compartment of the epithelium known as a primary follicle. The wall of the primary follicle is composed of outer follicular epithelial cells. While growing from about 15–70 μm in diameter, each oocyte gradually recruits a set of about 950 non-epithelial inner follicular cells. These cells co-differentiate in sets with each oocyte, but test cells never appear. The first filamentous components of the vitelline coat appear on the surface of an oocyte in places where it is in contact with undifferentiated (stage 2) inner follicular cells. Each fully differentiated inner follicular cell stores adhesive precursors in a large compartment of the endoplasmic reticulum and probably secretes components of the vitelline coat. There is no evidence that the outer follicular epithelial cells transform into inner follicular cells by dedifferentiation as has often been assumed. Inner follicular cells, in stage 1, are nearly identical to hemoblasts. Hemoblasts may form the inner follicular cells, but to do this they would have to cross the outer follicular epithelium and this phenomenon has not yet been seen.     

A comparative study of sperm postspawning destruction in flatfishes Hippoglossoides (Cleisthenes) herzensteini and Hippoglossoides dubius (Teleostei, Pleuronectidae)

Ultrastructural aspects of sperm destruction patterns were offered as additional cytological parameters for evaluation of the genus affinity of flatfishes Hippoglossoides dubius and Cleisthenes herzensteini. At the beginning of spermatozoan destruction, cell membrane in both species was found swollen, besides, discontinuity of membranes was observed, and membraneous parts were seen separating from sparmatozoa. We observed the ability of separated membraneous parts to aggregate to twisting conglomerates that wind round the objects of destruction. In H. dubius the membraneous conglomerates wound round spermatozoa, and after that such spermatozoa were phagocyted by follicular cells. In C. herzensteini, the membraneous conglomerates grasped the particles of destructed spermatozoa: the formed residual bodies were collected in the gonad lumen but not phagocyted by follicular cells. The expressiveness of the differences found in the pattern of sperm destruction is so considerable that, in the authors' opinion, these data are to supplement a list of criteria making reasonable reconsideration of the taxonomic status of C. herzensteini: its belonging to the genus Hippoglossoides, and establishing of the genus Cleisthenes as an independent rank.     

Induction of germinal vesicle breakdown in Xenopus laevis oocytes: response of denuded oocytes to progesterone and insulin

Denuded oocytes freed of their vitelline envelope have been prepared by two methods, enzymatically with pronase and manually by microdissection. The response of denuded oocytes to progesterone, in terms of germinal vesicle breakdown (GVBD), was similar to that obtained with defolliculated oocytes (separated with collagenase from follicle cells, but still keeping their vitelline membrane). The same conclusion was drawn with respect to morphological features of the oocyte surface observed by transmission and scanning electron microscopy, before and after progesterone-induced GVBD. The synergistic effect of insulin and progesterone in denuded oocytes was comparable to that observed in defolliculated oocytes. Multiplication stimulating activity (MSA) had the same effect as insulin. These observations indicate that hormones act directly upon oocytes, without interference of the surrounding vitelline envelope and follicle cells.     

The ultrastructure and function of follicle cells in Foucartia squamulata (Herbst) (Curculionidae)

Summary The follicle cells of Foucartia squamulata are involved in the formation of both vitelline membrane and chorion. Precursors for these egg coverings are synthesized by the rough endoplasmic reticulum and condensed within dictyosomes. The vitelline membrane and the chorion appear on the oocyte surface simultaneously, which is an unusual phenomenon for insects. The follicular epithelium has not been found to contribute to vitellogenesis in the species under study.     

Scanning and transmission electron microscopy of the female reproductive system of Schistosoma margrebowiei Le Roux, 1933

Transmission electron microscopy shows that the uterus of female Schistosoma margrebowiei possesses the same ultrastructure as that of the tegument but lacks spines and sense organs. It does not possess secretory cells and opens at the gonopore which by scanning electron microscopy was seen to be composed of numerous leaf-like protrusions. The morphology of the ovary is comparable with that of other Digenea. Immature and mature ova possess cortically arranged granules and occur within the posterior zone of the ovary. Cilia and lamellae line the luminal surface of the oviduct and ootype, the lamellae running unidirectionally along the duct. Only a single type of secretory cell is seen within Mehlis' gland and this produces dense bodies which are associated with Goldi bodies. Narrow cytoplasmic channels supported by microtubules deliver these secretory bodies to the ootype. The vitelline duct is lined with cilia and lamellae and the vitelline gland contains four types of cells, S1, S2, S3 and S4. Calcareous corpuscles are found within mature S4 cells.     

Effect of cytochalasin D on cell morphology and AcMNPV replication in a Spodoptera frugiperda cell line

Cytochalasin D (CD) is a specific inhibitor of actin microfilament elongation and has been used to identify actin-dependent cellular processes. In this study we observed the effects of this inhibitor on Autographa californica M nuclear polyhedrosis virus infected and uninfected IPLB-SF-21 cells by electron microscopy. The cytochalasin D-induced morphological effects detected in uninfected cells included lobulate nuclei, double nuclei, long retraction processes, increased zeiosis, more frequent plasma membrane indentations, increased vacuolation, more numerous coated pits and vesicles, filamentous masses in the cytoplasm, and decreased surface microvilli. Observation of infected cells treated with CD revealed that viral morphogenesis was severely affected. Few normal-appearing nucleocapsids were seen in the nucleus, and none were detected in the cytoplasm. Instead, long capsid-like tubular structures appeared juxtaposed to the inner nuclear membrane. Very infrequently sections of these structures contained electron dense material. The center of the nucleus contained electron-dense, spidery-like structures, presumably viral DNA. Normal virus was not observed to bud from the plasma membrane but electron-lucent, coreless-particles were. By 50 hr postinfection occasional polyhedra appeared, but these contained few or no enveloped virions. The intranuclear fibrous masses normally associated with infection were significantly reduced. These observations suggest that viral morphogenesis, especially nucleocapsid assembly, is an actin-dependent process.     

FINE STRUCTURE OF LOACH OOCYTES DURING MATURATION IN VITRO

The morphological changes during in vitro maturation of Misgurnus anguillicaudatus oocyte are described. The process of oocyte maturation can be divided into three provisional stages based on morphological events. Fully-grown, immature oocytes are opaque yellowish-white. The morphological characteristics of their ooplasm are the existence of annulate lamellae, a mass of long mitochondria and an electron dense layer beneath the vitelline surface. Three hr after a 1 hr exposure to corticosterone, these structures disappear and the cortical ooplasm becomes semi-transparent. In this stage of the maturation process (Stage I), the germinal vesicle, without a nucleolus, moves toward the animal pole, and scattered cytoplasmic inclusions approach the vitelline surface. Six hr after exposure to the hormone (Stage II), the whole ooplasm becomes semi-transparent and large yolk platelets are seen in the animal pole region. Tubular endoplasmic reticula develop throughout the ooplasm and some cortical alveoli (CA) become aligned beneath the vitelline surface. Nine hr after exposure to the hormone (Stage III), the oocyte chorion separates from the follicle cells. Most CA align beneath the vitelline surface and cytoplasm accumulates in the cortical region of the animal hemisphere.     

Phagocytosis of yeast by human oocytes: Fine structural observations

Fine-structure observations have been made on the interaction between invasive yeast cells and human oocytes. The yeast appear to make their way through the zona pellucida and once in the perivitelline space are incorporated into phagocytic vacuoles by surface activity of the oocyte. The yeast attach to the vitelline membrane via fuzzy surface material on the cell wall, and incorporation appears to be aided by oocyte microvillar activity. Coated pits in the oocyte plasma membrane are incorporated into the phagosomes, but no lysosomal activity is seen, and neither oocytes nor yeast cels appear to undergo degeneration in the time frame investigated.     

Schistosoma mansoni: the effects of a subcurative dose of praziquantel on the ultrastructure of worms in vivo

The in vivo effects of a subcutaneously-administered subcurative dose (200 mg/kg body weight of mouse) of praziquantel on the structure of Schistosoma mansoni was investigated. Worms were collected at varying times post-treatment and processed for both SEM and TEM examination. Praziquantel caused extensive structural changes to both male and female worms within 15 min of treatment although variations in the amount of drug-induced damaged was observed between male and female worms. In female worms although some tegumental vacuolation was observed within 15 min, the major structural change was an often extensive vacuolisation of the subtegumental tissues followed by varying degrees of structural disruption to the subtegumental and gastrodermal musculature. In male worms the initial effects were a vacuolisation of parts of the dorsal tegument and loss of tegumental cytoplasm due to the pinching off of evaginations of the outer surface. With increasing time post-treatment there was an increase in the amount of tegumental damage, particularly in male worms, with total disruption of parts of the outer surface occurring. Also in male worms there was an increase in the amounts of vacuolisation of the parenchymal tissues and in the degree of structural damage to the musculature. In those female worms where subtegumental damage was not extensive changes in the structure of the differentiating vitelline cells were noted.     

大鼠中枢神经系统衰老的形态学研究:Ⅵ.大脑皮质胶质细胞的超微结构变化

对幼年、成年与老年Wistar大鼠大脑躯感皮质的胶质细胞的电镜研究表明:老年大鼠胶质细胞脂褐素增加和卫星化增多;在胶质与神经元胞体之间,神经元的胞质膜和胶质贴近处出现表面下复合器的情况也增多。星形胶质细胞还有胞质肥大和微丝增多的倾向。在个别老年动物中见到一种特殊的多层平行膜板状髓鞘样结构出现于胶质与神经元胞体之间。     

The Chaetopterus vitelline envelope is not necessary for the gamete interactions that lead to fertilization

It has been recently shown that, in several genera of annelids, including Chaetopterus, fertilizing sperm attach to and fuse with egg microvilli which penetrate the vitelline envelope. This suggests that the annelid vitelline envelope may have no direct or obligatory role in normal fertilization. The present study was undertaken to investigate the involvement of the vitelline envelope in fertilization in Chaetopterus experimentally, by examining the fertilization of vitelline envelope-free eggs quantitatively and qualitatively. Brief exposure of the eggs to isotonic sucrose-EDTA removed the vitelline envelope as determined by both phase-contrast and electron microscopy, rendered the eggs more sensitive to polyspermy and substantially reduced the binding of supernumerary sperm to eggs but did not decrease fertilizability as determined by sperm dilution assay and did not make the eggs more sensitive to cross-fertilization. The events of fertilization were examined by electron microscopy and found to be very similar in vitelline envelope-free eggs to those in intact eggs. We conclude that the vitelline envelope in Chaetopterus has binding sites for sperm but that it has no obligatory role in fertilization and is primarily involved in the prevention of polyspermy.     

Further evidence of a role for abscisic acid in conversion of somatic embryos ofDaucus carota

Summary Somatic embryogenesis has been shown to be an imperfect recapitulation of stages involved to form embryos from vegetative tissues. Although abscisic acid has been implicated in normalizing development, studies that specifically investigate conversion (vegetative leaf initiation) in somatic embryos are lacking. This report documents a follow-up of a study that implicated abscisic acid as a vital factor in allowing embryos ofDaucus carota to progress to the plantlet stage. Abscisic acid was determined to enhance conversion at doses ranging from 1 to 50 µM. Younger embryo stages were more responsive to abscisic acid application with regards to plantlet recovery. Pulses of abscisic acid were shown to elicit more rapid response with younger embryo stages, indicating more plastic development. Fluridone, an abscisic acid synthesis inhibitor, was shown to dramatically reduce conversion, even at low doses (<5µM). When abscisic acid was applied concurrently with fluridone, partial restoration of conversion was observed. Histologically, fluridone was seen to cause pronounced vacuolation in the shoot apical notch which resulted in the loss of meristematic cells, negating conversion capacity. Quantitation of total cytoplasmic area showed that abscisic acid reduced vacuolar intrusion into the apical notch, while fluridone caused a significant increase in vacuolation of cells in this region. This report documents further evidence of a role for abscisic acid in plantlet establishment from somatic embryos ofDaucus carota.     

The study of the ultrastructure of the female reproductive system in a parasite of bats Allassogonoporus amphoraeformis (Digenea: Allassogonoporidae)

The morphology and fine structure of the female reproductive system of allassogonoporid trematode Allassogonoporus amphoraeformis have been described for the first time. The ovary consists of the germ cells being at various developmental stages and supporting cells of two types. The oviduct, seminal receptacle with its short duct and the proximal portion of Laurer's canal are lined by flattened cellular epithelium with lamellae and cilia on its luminal surface and well-developed basal infoldings. The distal part of Laurer's canal and metraterm are tegumental in structure and are characterized by sparse secretory inclusions and lacking of spines. Mehlis' glands of two types open into ootype. The uterus wall is composed of highly flattened epithelial cells surrounded by basal lamina and sparse muscle bundles. Vitelline lobules consist only of the vitelline cells at various developmental stages. The mature vitelline cells contain two types of inclusions: vitelline droplets and rarely scattered lipids. Vitelline ducts are lined by cellular epithelium with highly folded luminal surface and devoid of cilia. Presented results are compared with earlier obtained data on other lecithodendrioiden trematode Prosthodendrium ascidia ([symbol: see text], 1990).     

Morphology of the surface of normal and virus transformed cells in vitro]

The cell surface morphology of two cell lines--from the mink lung (Mv1Lu) and from the Kirsten sarcoma virus transformed derivate (Ki-Mv1Lu)--was studied by scanning electron microscopy. Marked differences are seen in cell morphology of these two lines at high cell densities. Mv1Lu cells at high densities had uniform flat polygonal shape with microvilli at their surface. A marked diversity in cell morphology was characteristic of Ki-Mv1Lu cells at comparable cell densities: variation in shape, in thickness degrees, and in the expression of cell surface ultrastructure (microvilli, blebs, filopodia). No dependence of Ki-Mv1Lu cell morphology from cell densities was observed. At low cell densities of Mv1Lu cells, cells with the morphology differing from the typical pattern of confluent Mv1Lu cells were seen. Morphological diversity of these cells was comparable with that of Ki-Mv1Lu cells. Nothing has been found in cell surface morphology that could be absolutely specific for transformed cells only.     

Studies on fertilization in the ascidians : Fucosyl sites on vitelline coat of Ciona intestinalis

The vitelline coat (originally called chorion) of the ascidian egg is the site where species-specific recognition and binding of spermatozoa occurs. Recent findings from this laboratory have suggested that fucosyl residues are present on the vitelline coat of Ciona intestinalis eggs and play an important role in the process of fertilization. The results reported in this paper confirm and extend those findings. With Fucose Binding Protein (FBP) and Fucosyl-Ferritin as markers, fucosyl sites have been localized on the fibrillar tufts emerging from the outer surface of the vitelline coat, both on glycerol-treated eggs and on living eggs deprived of follicle cells at pH 5. Observations on isolated vitelline coats have shown that the inner surface does not contain fucosyl sites. Studies performed with ¹²⁵I-FBP on glycerol-treated eggs have indicated that two distinct classes of fucosyl sites are present on the vitelline coat. The association constants for FBP of the high affinity and of the low affinity class are 2.3×10⁶ and 4.1×10⁵ respectively. The gel electrophoresis of the proteins extracted in sodium dodecyl sulfate (SDS) from sonicated vitelline coats has shown three fucosyl-containing polypeptide bands.