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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 145 (1974), S. 223-226 
    ISSN: 1432-0568
    Keywords: Rat ; Liver ; Bile ducts ; Cilia ; Scanning Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Numerous cilia have been demonstrated by SEM in cells of rat perilobular and portal bile ducts and ductules. Generally these cilia appear as long, cylindrical evaginations of the plasma membrane. Some of them are so long that, curving and twisting at many points, they cross the ductal lumen. It has been suggested that they may be related to a continual mixing up and propulsion of the bile product down the biliary tree.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 541 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Medical electron microscopy 32 (1999), S. 67-78 
    ISSN: 1437-773X
    Keywords: Key words Electron microscopy ; Human yolk sac ; Yolk stalk ; Vitelline duct ; Human embryo ; Human development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Organogenesis occurs during the first 8 weeks of human embryonic development; in consequence, early human growth and development take place before and in the absence of fully developed internal organs. During this period, normal development depends on several factors, but two are imperative: nutrition and a functional transport system for the distribution of nutrients and for waste disposal. The yolk sac (YS), a highly differentiated adnexal organ, is known to accomplish this fundamental task during early pregnancy. In this review, we summarize our contribution to the understanding of early human embryology, focusing interest on analysis of the morphofunctional link that is established between the human embryo and the YS during the embryonic period. Embryos were collected from the gestational sac after salpingectomies performed on patients with singleton pregnancies occurring in the fallopian tube. Samples of YS were taken from 20 human embryos at Carnegie stages ranging from 12 to 20. The age of the embryo was estimated from data of the patient's last menstrual history and confirmed from crown-rump length measurements and morphological characteristics of the specimen. The samples were fixed in 3% glutaraldehyde and then postfixed in 2% osmium tetroxide and prepared for light, transmission, and scanning electron microscopy according to conventional techniques. The samples were examined with a Philips 301 EM and an S-4000 Hitachi field emission SEM. The yolk stalk, and the YS wall with its corresponding endodermal, mesenchymal, and mesothelial layers, were analyzed. In accordance with their morphological features, the endodermal cells are equipped with organelles to fulfill several functions that are expressed in absorption from the vitelline cavity via microvilli present into the outer cell surface, in secretion to the extracellular space, and in the synthesis of numerous proteins which are transported by the bloodstream to the embryo. The mesothelial surface is provided with cell-surface differentiation that promotes a protective coat to prevent damage from compression or friction of the YS wall against the amnios, umbilical cord, and chorionic cavity wall during growth. The mesenchyme is the main site for blood vessel formation and gives rise to a network that provides the embryo with nutrients and a means of waste disposal. A critical analysis of the role of the endodermal vesicle in the production of fluid that is accumulated in the YS, and of the role that the vitelline duct play in the exchange function between the YS and intestinal tract, is presented. We have demonstrated that the vitelline duct is not functional after week 5 because of the closure of its lumen. This finding is discussed with reference to the biological meaning of the vitelline duct and its functional period of activity, and its possible role in the physiology of exchange during the embryonic period is assessed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-7330
    Keywords: blastocyst ; coculture ; human granulosa cells ; human embryos ; IVF implantation failures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Our purpose was to determine the effects of thecoculture of embryos on human granulosa cells (GCs) inpatients in the first cycle of IVF-ET treatment and in patientswith repeated implantation failures and to investigate thepresence of specific proteins in a 48-hr GC conditionedmedium and the GC ultrastructural characteristics. Methods: Eighteen patients with tubal or idiopathicinfertility were enrolled in this study: 7 patients (Trial 1) were inthe first cycle of IVF-ET treatment and 11 patients (Trial 2)had repeated implantation failures (one to five). Embryosfrom each patient were cocultured randomly either onhomologous granulosa cells or on a conventional culturemedium. Results: At the end of the coculture period (day 5 or 6),50% of the embryos (Trial 1) reached the blastocyst stage,with respect to 35% in Trial 2. The pregnancy rate perretrieval was 14.2 and 9%, respectively, in Trial 1 and inTrial 2. Many conditioned media showed proteins of 24–29kDa. and some of them showed additional proteins of 90kDa. The ultrastructural analysis of GCs showed healthy,metabolically active, protein-synthesizing, and mostlysteroidogenic cells. Conclusions: GC cultures improve embryo development butnot pregnancy rates both in Trial 1 and in Trial 2.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-7330
    Keywords: oocyte ; zona pellucida ; in vitro fertilization ; scanning electron microscopy ; gamete interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The structure of the zona pellucida and the early interactions between human oocytes and spermatozoa were investigated in an in vitro fertilization program. Thirty-five mature (preovulatory) oocytes, 10 immature oocytes lacking a germinal vesicle, and 11 atretic oocytes which had not undergone fertilization at 10–20 hr after insemination were studied by light and scanning electron microscopy. Observed through employment of these techniques, the zona pellucida showed two basically different patterns: a mesh-like, spongy structure having wide and/or close meshes; and a compact, smooth surface. The smooth-surfaced zona was most commonly seen in the cultured oocytes belonging to the immature and atretic groups. These observations seem to show that the spongy appearance of the zona pellucida is related mainly to oocyte development and maturity. In this study, greater numbers of penetrating spermatozoa were noted on oocytes showing the mesh-like zona, in contrast to the presence of a few sperm flattened against its surface or the frank absence of sperm associated with oocytes having the more compact, smooth zona. It is likely that the condensation of the outer aspect of the zona pellucida causes a disorientation of sperm-binding sites, which would probably result in markedly reduced binding and penetration capacity with spermatozoa. These changes might ultimately lead to impairment of in vitro oocyte fertilizability.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 68 (1965), S. 308-319 
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé On a effectué une étude ultrastructurale sur les ≪corps de Call et d'Exner≫. Ceux-ci se montrent constitués, sous leur aspect le plus typique, par une couronne de cellules de la granulosa disposées autour d'une cavité pleine d'un liquide semblable au ≪liquor folliculi ≫. Les cellules, de forme irrégulière, accolées dans leur partie proche du ≪corps≫ et écartées dans celle éloignée, déterminent des fentes dans lesquelles s'insinuent des groupes d'autres cellules voisines; la membrane cytoplasmique, parfois présente sous forme de microvilloités, parfois incisée, montre de fréquentes interruptions; le cytoplasme riche en ribosomes libres et adhérant aux parois du réticule endoplasmique (ergastoplasme), possède en outre un appareil de Golgi modérément développé et de nombreuses mitochondries; le noyau, très volumineux, présente à l'intérieur un nucléole grossièrement réticulé. Le ≪corps de Call et d'Exner≫ proprement dit est, au contraire, constitué par une cavité unitaire d'aspect à peu près sphérique d'environ μ 15–30 de diamètre, pleine d'un liquide dont les caractéristiques sont comparables à celles du ≪liquor folliculi≫; dans cette cavité on voit un fin réseau à mailles irrégulières, tandis que sa surface montre une mince zone de ≪condensation≫. L'aspect ultrastructural des cellules disposées autour des ≪corps de Call et d'Exner≫ est caractérisé par des cellules en élaboration, ce qui laisse penser qu'une partie de cette élaboration peut être versée à l'intérieur du ≪corps≫, en contribuant ainsi à l'augmentation de son volume. En ce qui concerne, enfin, le réticule que l'on voit à l'intérieur du ≪corps≫ il est vraisemblable qu'il soit du à des phénomènes de condensation et consécutif à un état physicochimique particulier du liquide endocavitaire.
    Notes: Summary The so-called “Call-Exner bodies” have been found to be formed, in their most typical shape, by a ring of granulosa cells enclosing a cavity filled with a fluid comparable to the liquor folliculi. The cells, irregular in shape, lying side by side in their portions closer to the “body” and far apart in their distal portions leave open spaces which are occupied by prolongations of adjacent cells. The cytoplasmic membrane, sometimes forming mierovilli, sometimes incisions, presents a discontinuous aspect; the cytoplasm is very rich in ribosomes which can be free or sticking to the walls of the endoplasmic reticulum (ergastoplasm). It has a fairly developed Golgi's apparatus and numerous mitochondria, sometimes open. The very voluminous nucleus shows internally a roughly reticulated nucleolus. The “Call-Exner body”, on the other hand, is a unitary cavity approximately spherical in shape, having about a 15–30 micron diameter filled with a fluid characteristically similar to the liquor folliculi, which shows internally a fine reticulation of irregular meshwork, while a thin “condensation zone” can bee seen peripherically. The ultrastructural aspect of the cells radiating from the Call-Exner bodies is typical of cells in formation. Therefore we cannot exclude the possibility that a portion of the substances elaborated by the cells may be thrown into the center of the “body”, thus contributing to its increase in volume. The mesh-like structure visible inside the “body” may be due to condensation phenomena following a particular physico-chemichal change in the endocavitary luid.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 98 (1969), S. 233-245 
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An electron microscope study of a number of preparations of human corpora lutea from the first phases of differentiation of the primitive luteal cell to its gradual involution have yielded the following results: the morphological changes that take space in the luteal cell in the course of its growth and involution are characterized by the presence in the cytoplasm of more and more vesicles of the smooth endoplasmic reticulum; and also by the appearance of villus-shaped “cristae” in the mitochondria, in the matrix of which there may sometimes be discerned an amorphous material with a different electronic density; and by the presence of lipid droplets and of lysosomes in the cell during its secretory activity. Subsequently, in the involutive phase, the vacuolization of the endoplasmic reticulum becomes more pronounced with formation of myelinic figures, rupture of the external membranes of the mitochondria and increase of the lipids, of the autophagic vacuoles and of the polymorphous lysosomes. In view of the close contiguity between the lipid droplets, the mitochondria and the vesicles of the endoplasmic reticulum during the secretory phase, the opinion is advanced that while the lipid droplets may constitute reserve material for the synthesis of hormones, the mitochondria and the vesicles of the endoplasmic reticulum with their enzymes may play a part in the process of steroidogenesis. On the other hand the possibility cannot be excluded that the lysosomes, which are also numerous during the phase of functional activity of the corpus luteum, may play a part in a mechanism regulating cellular secretion. In view of the fact that the plasma membrane shows considerable expansion in the zones where the lutein cells are in close contact with the blood capillaries, it is believed that the excretion of the material produced takes place by diffusion in the form of small particles of probably molecular size.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0878
    Keywords: Key words: Ovary ; Vascularization ; Vascular corrosion casts ; Scanning electron microscopy ; Countercurrent mechanism ; Rabbit (New Zealand white)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Ovarian angioarchitecture was studied by scanning electron microscopy of vascular corrosion casts in estrous, pseudopregnant (stimulated with human chorionic gonadotropin) and pregnant rabbits. In all samples, the proper ovarian branch of the ovarian artery (ramus ovaricus) entered the ovarian hilus near the caudal pole of the organ and ran parallel to the major axis of the hilus. The extraovarian venous drainage was formed by several vessels emptying into a distal large vein. The ramus ovaricus exhibited various degrees of coiling and branched in the medulla. The coiling of the ramus ovaricus and its ramifications were maintained in all samples. A venous meshwork and/or flat vein branches closely enveloped the arterial coils found in the hilus and outer medulla. At this level numerous arteriovenous contacts were demonstrated in all samples. The coiled arteries, prior to entering the ovarian cortex, supplied several small peripheral follicles which were drained by the hilar veins. In the cortex the coiled arteries branched in numerous thin, straight or slightly undulated arterioles which supplied developing estrous follicles and pseudopregnant corpora lutea. The arterioles supplying the pregnant corpora lutea were long, large and tightly spiraled. The venous drainage followed the modifications of the arterial supply. These data demonstrate that ovarian cycle and pregnancy induced significant changes in the cortical vessels, which adapted their structure to the temporary functional needs of the recruited follicles or corpora lutea. Hilar and medullary vessels have permanent structures that may represent morphological devices for (a) a continuous control of the blood flow (spiral arteries) and (b) a local recirculation of endocrine products (arteriovenous contacts) comparable to the ”countercurrent mechanism” previously shown to operate in ovaries of other species, but not yet found in rabbits.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 182 (1975), S. 499-513 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Bile canaliculi in the rat liver have been studied by scanning electron microscopy. They appear as half tubules carved out of the hepatocytes' surface. In several cases the bile channel bifurcates to form two or three long branches running on the same face of the cell. Therefore, by SEM it seems obvious that the same side of an hepatocyte may be used for bounding two or more bile canaliculi.Some bile canaliculi display a flexuous course and show lateral sacculations. Some of them are large and apparently similar to the short lateral branches of the bile canaliculus; others are smaller and arise obliquely from the subjacent cortical areas of the hepatocyte cytoplasm. These latter structures are best observed in stereo-views in which they appear as narrow intracellular projections bordered with a few microvilli, actually opening into the lumen of the bile canaliculus. The SEM results suggest that these sacculations probably correspond to short intracellular branches of the bile canaliculi.Zones of minimal distance (0.1 μ) between the space of Disse and the bile channel have been frequently observed. They are actually the zones where the intercellular clefts arising from the subendothelial space of Disse come into closest contact with the bile canaliculus and might serve as sites of simple diffusion of substances.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0878
    Keywords: Endometrium ; Rabbit ; Reproductive cycle ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes occurring on the surface of the uterine luminal epithelium of the rabbit during the estrous and progestational stages of the reproductive cycle were examined by scanning and transmission electron microscopy. The findings demonstrate that the uterine epithelium, or endometrium, contains two cell types: ciliated cells and nonciliated, microvillous cells. In estrous animals, ciliated cells, although not very numerous, were usually observed in small groups. However, at increasing intervals of time following mating, ciliated cells progressively disappeared from the endometrium until approximately eight to ten days post coitum, when they became scare. From several hours to four to five days following mating, extensive changes occurred on the surfaces of microvillous cells. When observed by TEM, these elements contained organelles typical of cells involved in the synthesis and secretion of glycoproteins. Furthermore, microvillous cells during this period displayed numerous apical protrusions of different sizes and shapes and containing material of varying electron density. Parallel SEM examinations of the same material confirmed the presence of these protrusions. Some of the protrusions appeared as spheroidal masses attached to the cytoplasm by means of a cytoplasmic strand. Other surface masses were clearly unattached to the cell surface and were distributed (1) on the surface of microvillous cells, (2) on the cilia of adjacent ciliated cells, and (3) on the surface of spermatozoa. Changes occurring on the luminal surface during the early postcoital period are interpreted as an expression of morphodynamic processes likely involving coupled secretion (exocytosis) and resorption (endocytosis) of luminal material. The observations presented here also demonstrate that between six and ten days post coitum, the rabbit endometrium contained increasing numbers of enlarged, nonciliated cells that probably arose by the fusion of smaller, microvillous elements.
    Type of Medium: Electronic Resource
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