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Day 1
Stage 1, fertilization, the zygote is formed following fertilization -
Day 2
Stage 2, the morula is formed -
Day 3
Blastocyst is formed -
Day 4
Stage 3, the blastocyst hatches (the zona pellucida is lost) -
Day 5
Late secretory phase, the blastocyst is free-floating -
Day 6
Stage 4, the initial phase of the implantation process -
Days 7-12
Stage 5, implantation (where the embryo adheres to the wall of the uterus) -
Days 13-15
Sage 6, chorionic cavity (help begin the functional units of the placenta) -
Days 15-17
Stage 7, gastrulation is continuing as the cells migrate from the epiblast, continuing to form the mesoderm -
Days 17-19
Stage 8, the neural groove and folds are first seen, neural neurogenesis -
Days 19-21
Stage 9, somites have begun to form and number between 1 to 3 somite pairs -
Days 22-23
Stage 10, neural folds in region developing brain, heart begins to beat -
Days 23-26
Stage 11, shows key features of heart tube and neural plate, peristaltic flow begins -
Days 26-30
Stage 12, neural tube continues to close by day 27 neural tube is usually completely closed. Stage 13 starts day 28. -
Days 28-32
Stage 13, the embryos CRL is about 4-6 mm, neural tube continues to close -
Days 31-35
Stage 14, the heart and the circulatory system takes shape ( a bulge indicates where the heart is developing) -
Days 35-38
Stage 15, the uterus begins to grow slightly, hormone levels rise rapidly, the neural tube is still under construction -
Days 37-42
Stage 16, fetuses body takes on C shape, small buds that will eventually become the arms and legs are visible -
Days 42-44
Stage 17, the arm and leg buds become longer, the facial features start to show such as the eyes, nose, and ears -
Days 44-48
Stage 18, heart and brain become more complex during this time, arm and leg joints are starting to form too -
Days 48-51
Stage 19, eyes, ears, and nose and cheeks are more visible at this time, the baby also is developing a permanent set of kidneys -
Days 51-53
Stage 20, the tadpole-like form at the bottom of the fetus is now gone, fingers and toes continue to develop as they are still somewhat webbed -
Days 53-54
Stage 21, fetus taste's buds begin to form as the baby prepares for its first meal -
Days 54-56
Stage 22, eyelids develop, an upper lip is forming, the beginnings of a neck of starting
