ANAT 1502 Embryology Chapter 5

ANAT 1502 Embryology Chapter 5 - CH. 5 The 3rd Week of...

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CH. 5 – The 3 rd Week of Development Gastrulation: Formation of Germ layers - bilaminar embryonic disc trilaminar embryonic disc - beginning of morphogenesis development of form and structure of organs and parts - begins with formation of primitive streak - 3 layers: o Ectoderm: epidermis, central/peripheral nervous systems, retina, others o Endoderm: epithelial linings of respiratory and GI tracts and assoc. organs o Mesoderm: smooth muscular coats, CT’s, and vessels, cardiovascular, blood cells, bone marrow, skeleton, striated muscles, and reproductive and excretory organs. Primitive Streak - Thickened, linear band of epiblast. - Caudally, on median plane, and dorsal side of embryonic disc - Result of migration of epiblast cells to median plane of embryonic disc - Streak elongates caudally cranial end forms primitive node - Primitive groove develops in streak, continuous w/ small depression in the primitive node primitive pit o A result of invagination of epiblastic cells - Streak allows craniocaudal axis, cranial end, caudal end, ventral, dorsal, and left and right sides to be identified. - Mesenchymal cells leave deep portion of Streak and form mesoblast – loose network of embryonic CT that forms supporting tissues of embryo mesoblast embryonic mesoderm - Primitive streak cells (mesenchymal) displace hypoblast embryonic endoderm - Mesenchymal cells from primitive streak fibroblasts, chondroblasts, osteoblasts, all 3 germ layers in embryo. Notochordal Process and Notochord
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This note was uploaded on 11/21/2011 for the course ANAT 1502 taught by Professor Johnh.romfh during the Spring '10 term at Life Chiropractic College West.

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ANAT 1502 Embryology Chapter 5 - CH. 5 The 3rd Week of...

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