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Note:The limb buds first appear around 4 weeks after fertilization. These humble buds will give rise to complete fingers and toes, elbows and knees, and arms and legs—all in the next three to four weeks!Label Key:1. right upper limb 2. spine 3. right lower limb bud with marginal vein 4. tip of lower spine (caudal eminence) 5. umbilical vein within umbilical cord | ||
All ages referenced to fertilization, not last menstrual period. |