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Epiboly
Epiboly describes one of the five major types of cell movements that occur in the gastrulation stage of embryonic development of some organisms. Epiboly is the spreading and thinning of the ectoderm while the endoderm and mesoderm layers move to the inside of the embryo. When undergoing epiboly, a monolayer of cells must undergo a physical change in shape in order to spread. Alternatively, multiple layers of cells can also undergo epiboly as the position of cells is changed or the cell layers undergo intercalation. While human embryos do not experience epiboly, this movement can be studied in sea urchins, tunicates, amphibians, and most commonly zebrafish. Zebrafish General movements Epiboly in zebrafish is the first coordinated cell movement, beginning at the dome stage late in the blastula period and continuing throughout gastrulation. At this point the zebrafish embryo contains three portions: an epithelial monolayer known as the enveloping layer (EVL), a yolk syncytial laye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Gastrulation
Gastrulation is the stage in the early embryonic development of most animals, during which the blastula (a single-layered hollow sphere of cells), or in mammals, the blastocyst, is reorganized into a two-layered or three-layered embryo known as the gastrula. Before gastrulation, the embryo is a continuous epithelial sheet of cells; by the end of gastrulation, the embryo has begun differentiation to establish distinct cell lineages, set up the basic axes of the body (e.g. dorsal–ventral, anterior–posterior), and internalized one or more cell types, including the prospective gut. Gastrula layers In triploblastic organisms, the gastrula is trilaminar (three-layered). These three germ layers are the ectoderm (outer layer), mesoderm (middle layer), and endoderm (inner layer).Mundlos 2009p. 422/ref>McGeady, 2004: p. 34 In diploblastic organisms, such as Cnidaria and Ctenophora, the gastrula has only ectoderm and endoderm. The two layers are also sometimes referred to as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Actin
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over 100 μM; its mass is roughly 42 kDa, with a diameter of 4 to 7 nm. An actin protein is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells. It can be present as either a free monomer called G-actin (globular) or as part of a linear polymer microfilament called F-actin (filamentous), both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division. Actin participates in many important cellular processes, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle mov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Amniotes
Amniotes are tetrapod vertebrate animals belonging to the clade Amniota, a large group that comprises the vast majority of living terrestrial and semiaquatic vertebrates. Amniotes evolved from amphibious stem tetrapod ancestors during the Carboniferous period. Amniota is defined as the smallest crown clade containing humans, the Greek tortoise, and the Nile crocodile. Amniotes are distinguished from the other living tetrapod clade — the non-amniote lissamphibians (frogs/ toads, salamanders/ newts and caecilians) — by: the development of three extraembryonic membranes ( amnion for embryonic protection, chorion for gas exchange, and allantois for metabolic waste disposal or storage); thicker and keratinized skin; costal respiration (breathing by expanding/constricting the rib cage); the presence of adrenocortical and chromaffin tissues as a discrete pair of glands near their kidneys; more complex kidneys; the presence of an astragalus for better ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Xenopus Laevis
The African clawed frog (''Xenopus laevis''), also known as simply xenopus, African clawed toad, African claw-toed frog or the ''platanna'') is a species of African aquatic frog of the family Pipidae. Its name is derived from the short black claws on its feet. The word ''Xenopus'' means 'strange foot' and ''laevis'' means 'smooth'. The species is found throughout much of Sub-Saharan Africa (Nigeria and Sudan to South Africa), and in isolated, introduced populations in North America, South America, Europe, and Asia. All species of the family Pipidae are tongueless, toothless and completely aquatic. They use their hands to shove food in their mouths and down their throats and a hyobranchial pump to draw or suck things in their mouth. Pipidae have powerful legs for swimming and lunging after food. They also use the claws on their feet to tear pieces of large food. They have no external eardrums, but instead subcutaneous cartilaginous disks that serve the same function. They use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cadherin
Cadherins (named for "calcium-dependent adhesion") are cell adhesion molecules important in forming adherens junctions that let cells adhere to each other. Cadherins are a class of type-1 transmembrane proteins, and they depend on calcium (Ca2+) ions to function, hence their name. Cell-cell adhesion is mediated by extracellular cadherin domains, whereas the Cadherin cytoplasmic region, intracellular cytoplasmic tail associates with numerous adaptors and signaling proteins, collectively referred to as the cadherin adhesome. Background The cadherin family is essential in maintaining cell-cell contact and regulating cytoskeletal complexes. The cadherin superfamily includes cadherins, protocadherins, desmogleins, desmocollins, and more. In structure, they share ''cadherin repeats'', which are the extracellular Ca2+-binding domains. There are multiple classes of cadherin molecules, each designated with a prefix for tissues with which it associates. Classical cadherins maintain the ton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Claudin
Claudins are a family of proteins which, along with occludin, are the most important components of the tight junctions ( zonulae occludentes). Tight junctions establish the paracellular barrier that controls the flow of molecules in the intercellular space between the cells of an epithelium. They have four transmembrane domains, with the N-terminus and the C-terminus in the cytoplasm. Structure Claudins are small (20–24/27 kilodalton (kDa)) transmembrane proteins which are found in many organisms, ranging from nematodes to human beings. They all have a very similar structure. Claudins span the cellular membrane 4 times, with the N-terminal end and the C-terminal end both located in the cytoplasm, and two extracellular loops which show the highest degree of conservation. Claudins have both cis and trans interactions between cell membranes. Cis-interactions is when claudins on the same membrane interact, one way they interact is by transmembrane domain having molecular inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Tight Junctions
Tight junctions, also known as occluding junctions or ''zonulae occludentes'' (singular, ''zonula occludens''), are multiprotein junctional complexes between epithelial cells, sealing and preventing leakage of solutes and water. They also play a critical role maintaining the structure and permeability of endothelial cells. Tight junctions may also serve as leaky pathways by forming selective channels for small cations, anions, or water. The corresponding junctions that occur in invertebrates are septate junctions. Structure Tight junctions are composed of a branching network of sealing strands, each strand acting independently from the others. Therefore, the efficiency of the junction in preventing ion passage increases exponentially with the number of strands. Each strand is formed from a row of transmembrane proteins embedded in both plasma membranes, with extracellular domains joining one another directly. There are at least 40 different proteins composing the tight junctio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cytochalasin B
Cytochalasin B, the name of which comes from the Greek ''cytos'' (cell) and ''chalasis'' (relaxation), is a cell-permeable mycotoxin. It was found that substoichiometric concentrations of cytochalasin B (CB) strongly inhibit network formation by actin filaments. Due to this, it is often used in cytological research. It inhibits cytoplasmic division by blocking the formation of contractile microfilaments. It inhibits cell movement and induces nuclear extrusion. Cytochalasin B shortens actin filaments by blocking monomer addition at the fast-growing end of polymers. Cytochalasin B inhibits glucose transport and platelet aggregation. It blocks adenosine-induced apoptotic body formation without affecting activation of endogenous ADP-ribosylation in leukemia HL-60 cells. It is also used in cloning through nuclear transfer. Here enucleated recipient cells are treated with cytochalasin B. Cytochalasin B makes the cytoplasm of the oocytes more fluid and makes it possible to aspirate the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Nocodazole
Nocodazole is an antineoplastic agent which exerts its effect in cells by interfering with the polymerization of microtubules. Microtubules are one type of fibre which constitutes the cytoskeleton, and the dynamic microtubule network has several important roles in the cell, including vesicular transport, forming the mitotic spindle and in cytokinesis. Several drugs including vincristine and colcemid are similar to nocodazole in that they interfere with microtubule polymerization. Nocodazole has been shown to decrease the oncogenic potential of cancer cells via another microtubules-independent mechanisms. Nocodazole stimulates the expression of LATS2 which potently inhibits the Wnt signaling pathway by abrogating the interaction between the Wnt-dependent transcriptional co-factors beta-catenin and BCL9. It is related to mebendazole by replacement of the left most benzene ring by thiophene. Use in cell biology research As nocodazole affects the cytoskeleton, it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
