Question

27. Bones of vertebrales are derived from embryonic
A. Ectoderm
B. Epiderm
C. Mesoderm
D. Endoderm
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Answer 1

When the early embryo consist of only two tissues layer , ectoderm and endoderm a longitudinal thickening appears as the result of multiplication of the ectodermal cells . This thickening the primitive ,streak gives rise to the notochord , and to the third basic layers ,mesoderm .