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Fertilization, zygote, Secretory Phase
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Blastocyst hatches
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Implantation
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Chorionic Cavity
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Neural neurogenesis, neural glove and folds are first seen
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The Heart begins to beat and the first functioning embryonic organ formed.
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The neural tube is normally completely closed, ventricular system now separated from amniotic fluid.
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Head- 1st, 2nd and 3rd pharyngeal arch, forebrain, site of lens placode, site of otic placode, stomodeum
Body- heart, liver, umbilical cord, mesonephric ridge visible externally as bulges. -
The spine is starting to form, with the very beginnings of the central nervous system. Blood vessels are also forming into what will become the umbilical cord
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Telencephalon areas of the future archicortex, paleocortex, and neocortex, become visible. smell olfactory nerve fibres enter the brain. Eyelid folds develop.
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Skeletal muscle forms by fusion of mononucleated myoblasts to form multinucleated myotubes. Bone is formed through a lengthy process involving ossification of a cartilage formed from mesenchyme.
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Scalp vascular plexus visible. Upper limbs begin to rotate ventrally
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Fingers and Toes start to lengthen. Upper and lower limbs rotate.
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The upper limbs longer and bent at elbow, hands and feet turned inward, foot with separated digits, wrist, hand with separated digits. Chorionic cavity is now lost by fusion with the expanding amniotic cavity
