13h 51min, jul 12, 2008 y - Hormone levels
Description:
During the fifth week of pregnancy the levels of HCG hormone produced by the blastocyst quickly increase. The embryo is made of three layers. The top layer is the ectoderm this will give the baby the outermost layer. In the middle layer the circulatory system will form.(Mayo Clinic)
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Gema
Growth and development timeline
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