Ultrastructure of intrauterine eggs: Evidence of early ovoviviparity in the caryophyllidean cestode Wenyonia virilis Woodland, 1923

2010 ◽  
Vol 55 (4) ◽  
Author(s):  
Daniel Młocicki ◽  
Zdzisław Świderski ◽  
John Mackiewicz ◽  
Mohammed Ibraheem
Keyword(s):  
Embryonic Development ◽  
Lipid Droplets ◽  
Outer Envelope ◽  
Large Nucleus ◽  
Egg Formation ◽  
Ultrastructural Evidence ◽  
Initial Stage ◽  
Granular Cytoplasm ◽  
Electron Lucent ◽  
Inner Envelope

AbstractUltrastructural evidence for early intraurerine embryonic development of Wenyonia virilis is presented. At the initial stage of egg formation, the fertilized oocyte or ovum is surrounded by numerous vitellocytes and newly formed eggshell. Individual vitellocytes undergo progressive fusion into a vitelline syncytium. During cleavage divisions, three types of blastomeres are formed: macromeres, mesomeres and micromeres. Two large macromeres contain a large nucleus with spherical nucleolus and numerous small heterochromatin islands dispersed in moderately electron-dense nucleoplasm. The granular cytoplasm shows a few large mitochondria. Medium-sized mesomeres contain a spherical nucleus with numerous heterochromatin islands, adjacent to the nuclear envelope, and a prominent electron-dense nucleolus. Their nuclei are embedded in granular cytoplasm with a few large and numerous small mitochondria and Golgi complexes. The small micromeres are characterized by presence of spherical nucleoli with large areas of highly condensed heterochromatin and a few islands of granular electron-lucent nucleoplasm. Their granular cytoplasm shows a few small lipid droplets and several spherical mitochondria. Majority of micromeres give rise to the hexacanth but many of them also undergo degeneration or apoptosis. Both mesomeres and macromeres are engaged in the formation of the oncospheral envelopes. The outer envelope is formed by a fusion of two macromeres whereas the inner envelope originates from a fusion of mesomeres. The intrauterine eggs of W. virilis usually contain an embryo at the early preoncopheral phase of development and possesses three primary envelopes: (1) thick eggshell; (2) thin cytoplasmic layer of the outer envelope and (3) inner envelope. Based on embryonic development, egg type and life-cycle characteristics, caryophyllideans tend to show closer affinities to spathebothriideans than to the former pseudophyllideans.

scholarly journals Osmophores of the fragrant orchid Gymnadenia conopsea L. (Orchidaceae)

2014 ◽  
Vol 70 (2) ◽  
pp. 91-96 ◽  
Author(s):  
Małgorzata Stpiczyńska
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Lipid Droplets ◽  
Secretory Vesicles ◽  
Large Nucleus ◽  
Orchid Species ◽  
Adaxial Surface ◽  
Gymnadenia Conopsea ◽  
Granular Cytoplasm

Osmophores of <em>Gymnadenia conopsea</em> are located on the adaxial surface of labellum and on distal parts of two lateral sepals. Osmophore cells are characterised with a large nucleus, and dense, granular cytoplasm, which contains numerous membranes of ER and large lipid droplets. Plastids are probably involved in the synthesis of fragrant substances and, contrary to the most of investigated orchid species, they do not contain starch. Numerous secretory vesicles take part in the secretion. Secreted fragrant substance migrates across the cell wall and through the pores in the cuticle. It is not accumulated on the osmophore cell surface.

Electron microscopy of embryonic envelope formation by the cestode proteocephalus longicollis (zeder, 1800)(proteocephalidea)

1978 ◽  
Vol 36 (2) ◽  
pp. 444-445
Author(s):  
Z. Swiderski ◽  
L. Subilia
Keyword(s):  
Electron Microscopy ◽  
Outer Envelope ◽  
Vitelline Cell ◽  
Fibrillar Material ◽  
Initial Stage ◽  
Advanced Stages ◽  
Vitelline Cells ◽  
Shell Globule ◽  
Pass Through ◽  
Inner Envelope

Four main embryonic envelopes, the capsule, outer envelope, inner envelope and oncospheral membrane, are formed around the developing embryos of Proteocephalus longicollis, a parasite of fishes.The capsule, formed from shell-globule material of vitelline cells, is the first embryonic envelope which encloses the fertilized oocyte and a single vitelline cell (Fig. 1) when they pass through the ootype and enter the uterus. At this initial stage of embryogenesis, the capsule is formed of two closely apposed membranes (Fig. 1, inset). In more advanced stages, the capsule slightly increases its volume, and a fine-fibrillar material accumulates in the space between its two limiting membranes (Fig. 2).

scholarly journals Synthesis and maintenance of lipid droplets are essential for mouse preimplantation embryonic development

Development ◽  
2019 ◽  
Vol 146 (22) ◽  
pp. dev181925 ◽  
Author(s):  
Ryutaro Aizawa ◽  
Megumi Ibayashi ◽  
Takayuki Tatsumi ◽  
Atsushi Yamamoto ◽  
Toshiaki Kokubo ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Lipid Droplets

Egg ultrastructure of the amabiliid cestode Tatria biremis Kowalewski, 1904 (Cyclophyllidea, Amabiliidae), with an emphasis on the oncospheral envelopes

2013 ◽  
Vol 58 (3) ◽  
Author(s):  
Vasyl Tkach ◽  
Zdzisław Świderski ◽  
Daniel Młocicki
Keyword(s):  
Cell Types ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Outer Envelope ◽  
Ultrastructural Studies ◽  
Egg Maturation ◽  
Ultrastructural Characteristics ◽  
Egg Envelopes ◽  
Host Infection ◽  
Inner Envelope

AbstractThis is the first report on the ultrastructure of eggs in the cestode family Amabiliidae Braun, 1900. The gravid proglottides of Tatria biremis easily detach from the strobila. Their thick-walled saccate uterus contains numerous rounded or oval eggs measuring about 30-32 μm in diameter. In the early preoncospheral phase, three primary embryonic envelopes are formed around the developing and differentiating embryos, namely: (1) vitelline capsule originating from vitellocyte material; (2) outer envelope formed by two macromeres, and (3) inner envelope originating from a fusion of three mesomeres. Thus, both the outer and inner envelopes of T. biremis eggs are cellular in origin and syncytial in nature. During egg maturation, the three primary embryonic envelopes undergo differentiation into fully formed oncospheral or egg envelopes. Most significant changes were observed in the inner envelope which becomes progressively subdivided into 3 sub-layers: the extra-embryophoral sub-layer, the embryophore, and the intra-embryophoral sub-layer, containing mesomere nuclei. The mature hexacanth is covered by a thin layer of the oncospheral tegument. Within the infective hexacanth larva, five cell types were distinguished: (1) a binucleated subtegumental cell; (2) U-shaped penetration gland; (3) nerve cells; (4) somatic cells representing the myocytons of both somatic and hook musculature, and (5) large germinative cells. Ultrastructural characteristics of T. biremis eggs are compared with those described in representatives of other cestode taxa. Since the functional ultrastructure of cestode egg envelopes is defined by multiple factors such as the type of life cycles, habitats and behaviour of the intermediate hosts, mode of the intermediate host infection, etc., ultrastructural studies of the greater diversity of cestodes are needed to obtain comparative data for fruitful analysis of cyclophyllidean cestode adaptations to their diverse life cycles.

scholarly journals Morphological features of lipid droplet transition during porcine oocyte fertilisation and early embryonic development to blastocyst in vivo and in vitro

Zygote ◽  
2002 ◽  
Vol 10 (4) ◽  
pp. 355-366 ◽  
Author(s):  
Kazuhiro Kikuchi ◽  
Hans Ekwall ◽  
Paisan Tienthai ◽  
Yasuhiro Kawai ◽  
Junko Noguchi ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Oocyte Maturation ◽  
Lipid Droplets ◽  
Early Embryonic Development ◽  
Oocyte Activation ◽  
Energy Status ◽  
Thin Sections ◽  
Porcine Oocyte

Lipid content in mammalian oocytes or embryos differs among species, with bovine and porcine oocytes and embryos showing large cytoplasmic droplets. These droplets are considered to play important roles in energy metabolism during oocyte maturation, fertilisation and early embryonic development, and also in the freezing ability of oocytes or embryos; however, their detailed distribution or function is not well understood. In the present study, changes in the distribution and morphology of porcine lipid droplets during in vivo and in vitro fertilisation, in contrast to parthenogenetic oocyte activation, as well as during their development to blastocyst stage, were evaluated by transmission electron microscopy (TEM). The analysis of semi-thin and ultra-thin sections by TEM showed conspicuous, large, electron-dense lipid droplets, sometimes associated with mitochondrial aggregates in the oocytes, irrespective of whether the oocytes had been matured in vivo or in vitro. Immediately after sperm penetration, the electron density of the lipid droplets was lost in both the in vivo and in vitro oocytes, the reduction being most evident in the oocytes developed in vitro. Density was restored in the pronculear oocytes, fully in the in vivo specimens but only partially in the in vitro ones. The number and size of the droplets seemed, however, to have decreased. At 2- to 4-cell and blastocyst stages, the features of the lipid droplets were almost the same as those of pronuclear oocytes, showing a homogeneous or saturated density in the in vivo embryos but a marbled or partially saturated appearance in the in vitro embryos. In vitro matured oocytes undergoing parthenogenesis had lipid droplets that resembled those of fertilised oocytes until the pronuclear stage. Overall, results indicate variations in both the morphology and amount of cytoplasmic lipid droplets during porcine oocyte maturation, fertilisation and early embryo development as well as differences between in vivo and in vitro development, suggesting both different energy status during preimplantation development in pigs and substantial differences between in vitro and in vivo development.

scholarly journals Embryonic development of Anodontites trapesialis (Lamarck, 1819) (Bivalvia: Mycetopodidae)

2011 ◽  
Vol 71 (1) ◽  
pp. 139-144 ◽  
Author(s):  
AT. Silva-Souza ◽  
P. Guardia-Felipi ◽  
NR. Arrebola
Keyword(s):  
Electron Microscopy ◽  
Embryonic Development ◽  
Phase Iii ◽  
Fish Farms ◽  
Egg Envelope ◽  
Initial Stage ◽  
Phases Of Development ◽  
Five Phases ◽  
First Time ◽  
Scanning Electron

The phases of embryonic development of Anodontites trapesialis lasidia are described for the first time. Adult specimens were obtained from two fish farms located in Londrina, Paraná, Brazil. The internal demibranchs of 120 individuals were studied using a routine histological technique; 70 of these carried eggs and/or larvae in the marsupium and were utilized for the description of the phases of embryonic development. The demibranchs of five specimens were evaluated by scanning electron microscopy to detail the morphology of the larvae. Five phases of development were established: phase I, corresponding to the initial stage of cleavage with the formation of apical cells; phase II, including the stages of the morula and blastula; phase III, where the gastrula forms; phase IV, where the larva formed is still inside the egg envelope; and phase V, where the lasidium can still be identified immediately after eclosion.

scholarly journals Drosophila Lipid Droplets Buffer the H2Av Supply to Protect Early Embryonic Development

2014 ◽  
Vol 24 (13) ◽  
pp. 1485-1491 ◽  
Author(s):  
Zhihuan Li ◽  
Matthew R. Johnson ◽  
Zhonghe Ke ◽  
Lili Chen ◽  
Michael A. Welte
Keyword(s):  
Embryonic Development ◽  
Lipid Droplets ◽  
Early Embryonic Development

Taenia crassiceps ultrastructural observations on the oncosphere and associated structures

1983 ◽  
Vol 57 (2) ◽  
pp. 101-113 ◽  
Author(s):  
M. W. K. Chew
Keyword(s):  
Basal Lamina ◽  
Epithelial Layer ◽  
Outer Envelope ◽  
Electron Microscopic ◽  
Taenia Crassiceps ◽  
Dense Bodies ◽  
Collar Region ◽  
Epithelial Membranes ◽  
Epithelial Layers ◽  
Inner Envelope

ABSTRACTElectron microscopic observations were made on unhatched eggs of Taenia crassiceps in utero. The outermost envelope consists of a thin, relatively smooth capsule over a highly convoluted outer envelope which contains a highly granulated cytoplasm and numerous mitochrondria. The inner envelope, consisting of a thick embryophore and the cytoplasmic component of the embryophore cell, resembles that found in most other taeniids. Three epithelial layers separate the oncosphere from the embryophore. While these layers are narrow and difficult to distinguish, the ‘oncospheral membrane’ is distinct, darkly stained and relatively thick. The oncospheral hook lies within the oncoblast with its blade portion held by cytoplasmic folds within a modified ‘sheath’ in the ‘basal epithelial layer’. Round, dense bodies are concentrated at the epithelial membranes around the ‘sheaths’. Hook muscles insert on the basal lamina at the ‘collar’ region of the hooks. Penetration gland cells are packed with numerous dense disc-shaped secretory bodies.

scholarly journals The Structure of Rhodospirillum rubrum

1959 ◽  
Vol 6 (2) ◽  
pp. 277-284 ◽  
Author(s):  
Donald D. Hickman ◽  
Albert W. Frenkel
Keyword(s):  
Electron Microscopy ◽  
Cell Surface ◽  
Light Microscopy ◽  
Photosynthetic Bacteria ◽  
Rhodospirillum Rubrum ◽  
Low Density ◽  
Outer Envelope ◽  
Cytoplasmic Bodies ◽  
Granular Cytoplasm ◽  
In Cells

Cells from serial cultures of R. rubrum, grown anaerobically in the light, were harvested at intervals from ½ to 15 days and sectioned for electron microscopy by conventional methods. Cells of this species possess a multilayered outer envelope, and the external cell surface is differentiated into ridges extending parallel or obliquely to the long axis of the cell. Cells from very young cultures resemble non-photosynthetic bacteria and contain only a granular cytoplasm, scattered high-density particles, and low-density areas corresponding to the chromatin areas observed by light microscopy. They contain neither the chromatophores nor the lamellar systems assumed by previous investigators to be characteristic of this species when grown anaerobically in the light. Chromatophores appear in cells from cultures older than about 12 hours, while systems of paired lamellae appear along with the chromatophores in cells from cultures older than about 8 days. Divergent opinions concerning the occurrence of chromatophores or lamellae in this species can be resolved on the basis of the age of cultures used in previous studies. Other changes occurring in cells from cultures of increasing age include the appearance of granular and reticulate cytoplasmic bodies and vacuoles, extension of the chromatin areas, and the appearance of a single membrane enclosing several chromatophores.

scholarly journals Homeostatic regulation of lipid droplet content in mammalian oocytes and embryos

Reproduction ◽  
2021 ◽  
Vol 162 (6) ◽  
pp. R99-R109
Author(s):  
Megumi Ibayashi ◽  
Ryutaro Aizawa ◽  
Junichiro Mitsui ◽  
Satoshi Tsukamoto
Keyword(s):  
Embryonic Development ◽  
Lipid Droplets ◽  
Neutral Lipids ◽  
Mammalian Species ◽  
Early Embryonic Development ◽  
Preimplantation Embryos ◽  
Physiological Importance ◽  
Bovine Oocytes ◽  
Mammalian Embryonic Development ◽  
Development Proceeds

Lipid droplets (LDs) consist of a core of neutral lipids such as triacylglycerols and cholesteryl esters covered by a phospholipid monolayer. Recent studies have shown that LDs not only store neutral lipids but are also associated with various physiological functions. LDs are found in most eukaryotic cells and vary in size and quantity. It has long been known that mammalian oocytes contain LDs. Porcine and bovine oocytes contain substantial amounts of LDs, which cause their cytoplasm to darken, whereas mouse and human oocytes are translucent due to their low LD content. A sufficient amount of LDs in mammalian oocytes has been thought to be associated with oocyte maturation and early embryonic development, but the necessity of LDs has been questioned because embryonic development proceeds normally even when LDs are removed. However, recent studies have revealed that LDs play a crucial role during implantation and that maintaining an appropriate amount of LDs is important for early embryonic development, even in mammalian species with low amounts of LDs in their oocytes. This suggests that a fine-tuned balance of LD content is essential for successful mammalian embryonic development. In this review, we discuss the physiological importance of LDs in mammalian oocytes and preimplantation embryos based on recent findings on LD biology.

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