Neural tut Sclerotome Paraxial mesoderm segmentation somite wall Notochord Dorsal aorta Blocks of tissue along axis Dermomyo o Somite(体节):20days,3 pairs Sdlorotomo per day, 42-44 pairs by the end of 5th M volome weeks - Sclerotome(生骨节): vertebra Antenor neuropore Myotome(生肌节) skeletal muscle Dermatome(生皮节): dermis B Posten neuropore 23 daysParaxial Mesoderm •Segmentation •Blocks of tissue along axis •Somite（体节）:20th days, 3 pairs/ per day,42-44 pairs by the end of 5th weeks -Sclerotome（生骨节）: vertebra -Myotome（生肌节）:skeletal muscle -Dermatome（生皮节）:dermis