Fetal Development Timeline

By emilyshearer21
  • Hour 1

    Hour 1

    Fertilization

  • Fertilized egg

    occurs with fertilization and is known as such for the first 12 hours
  • Hour 12

    Hour 12

    pronuclei join together

  • zygote stage begins

    occurs when the nuclear membrane of the ovum disappears and 23 male chromosomes meet 23 female chromosomes. both nuclei double to 46 chromosomes and then fuse.
  • hour 30

    hour 30

    first round of mitosis (cleavage)
  • hour 40

    hour 40

    second round of mitosis
  • hour 50

    hour 50

    third round of mitosis

  • embryonic stage begins

    begins when the third cleavage occurs and forms a morula
  • morula formed

    morula formed

  • day 6

    day 6

    64 cell embryo now called a blastocyst
  • day 8

    day 8

    implantation
  • day 10

    day 10

    ectopic pregnancy could occur
  • hatching

    hatching

  • day 12

    day 12

    disc with streak on the underside forms mesoderm

  • day 12

    hCG begins to be secreted

  • day 15

    first missed period
  • day 16

    day 16

    neural tube forms
  • day 22

    day 22

    heart begins to beat, arm and leg buds appear, yolk sac makes RBCs
  • day 35

    day 35

    face plates forming
  • day 36

    day 36

    cleft lip or palate may occur
  • week 6

    week 6

    muscles form, bent neck, webbed hands and feet, segmented back
  • week 7

    week 7

    fingers and toes separate, eyes and ears formed
  • day 50

    day 50

    amniocentesis can be performed
  • day 50

    day 50

    genitalia begins to differentiate, eyelids fuse, amnion surrounds fetus

  • fetal stage begins

    occurs when all organs are formed
  • week 9

    week 9

    chorionic villi sampling could be performed
  • month 6

    month 6

    eyes open, fat added under skin, head out of proportion to the body