http___livro-ensino-medio.f1cf.com.br_biologia_hr_biology-79.html_1.xml
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During the second week of embryonic development, the cells organize themselves forming germ layers: ectoderm and endoderm. The ectoderm forms the "floor" of the amniotic cavity, the endoderm forms the roof of the yolk sac. By the 13th day of development ini-ence to the stage of gastrulation, leading to the formation of the third booklet germination, the mesoderm. The cells of the germ layers divide, migrate and come together to form the various organ systems. It is between the fourth and eighth week that the organ systems begin to develop. As the tissues and organs are forming, the shape of the embryo is modified, and from the eighth week, the embryo begins to take shape distinctly human. And that INTERESTING! Let's see what the brochure cad germinal form? The ectoderm forms the peripheral nervous system, the central nervous system (brain and spinal cord), the epidermis and appendages (hair and nails), the epithelium of the eye, nose and ears; mammary glands and subcutaneous; pituitary and tooth enamel. The mesoderm forms the connective tissue, bone, smooth and striated muscles, cartilage, heart, blood and lymph vessels, kidneys, ovaries and testes, genital ducts, spleen, adrenal cortex and the serous membranes that line the body cavities. The endoderm forms the epithelial lining of the urinary bladder and the greater part of the urethra, thymus, liver and pancreas, the epithelial lining of the tympanic cavity, the tympanic antrum and the Eustachian tube, the parenchyma of the tonsils, the thyroid and parathyroid glands; the epithelial lining of the gastrointestinal and respiratory tracts. Representation of germ layers during gastrula. Source: Leidimeri dos Santos.
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Tijekom drugog tjedna embrionalnog razvoja, stanice se organiziraju formiranju klica sloja: ektoderm i endoderm. Ektoderm čini "kat" od amnionske šupljine, endoderm tvori krov žumanjčana vreća. Do 13. dana od razvoja ini-žaja u stadiju gastrulacije, što dovodi do stvaranja trećeg knjižici klijanja, mesoderm. Stanice za podjelu zametne slojeva, migriraju i dolaze zajedno u obliku raznih organskih sustava. To je između četvrtog i osmog tjedna da su orgulje sustavi počinju razvijati. Kao što su tkiva i organa formiranja, oblik embrija se mijenjati, a od osmog tjedna, embrij počinje se oblikovati izrazito čovjeka. to ZANIMLJIVO! Idemo vidjeti što brošure cad zametno oblik? Ektoderm čini periferni živčani sustav, središnji živčani sustav (mozak i leđna moždina), epidermis i dodacima (kosa i nokti), epitel očiju, nosa i ušiju mliječnih žlijezda i potkožnog tkiva, hipofize i zubnu caklinu. Mesoderm tvori vezivno tkivo, kosti, glatko i izbrazdan mišiće, hrskavicu, srce, krvne i limfne žile, bubrezi, jajnici i testisi, genitalne kanale, slezena, nadbubrežna korteks i serous membrane koje okružuju tjelesne šupljine. Endoderm tvori epitela sluznice mokraćnog mjehura i većem dijelu uretre, timus, jetra i gušterača, epitel sluznice membranskog šupljine, u membranskog antrumu i Eustahijeve cijevi, parenhima krajnika, štitnjače i paratiroidne žlijezde; epitel sluznice gastrointestinalnog i respiratornog trakta. Zastupljenost zametnih slojeva tijekom gastrule. Izvor: Leidimeri dos Santos.