2795073 stages of prenatal development 01 5a3040f6eb4d5200362d5553

Prenatal Development

By mackoch

  • Peimplantation Period

    Peimplantation Period
    The first week.
    Sperm and ovum unite!
    Zygote is created.
    Mitosis begins and duplicates cells.
    Eventually attaches to the uterine wall and becomes a blastocyte.
  • Period: to

    Pregnancy

  • Second Week

    Second Week
    • The implanted blastocyst grows by cells proliferating, and differentiating.
    • Morphogenesis in the cells also occur. This creates the germ layers within the blastocyst, and eventually becomes the bilaminar embryonic disc, which develops into the embryo as prenatal development continues.
    • Placenta develops.
    • Umbilical circulation develops.

  • Third Week

    Third Week
    • All three layers are noticeable: Endoderm, Mesoderm, and Ectoderm. Ectoderm - gives rise to the skin epidermis, the CNS, and other structures. Mesoderm - gives rise to the connective tissues. Endoderm - gives rise to the respiratory epithelium and cells of glands.
    • Cephalic end and Caudal end is formed. (both lined by endoderm)
    • Neural crest cells - develop from the neuroectoderm, and migrate from the crests of the folds and disperse into the mesenchyme.

  • Fourth Week

    Fourth Week
    • Embryonic folding occurs. Digestive tract begins to develop. Foregut: forms the primitive pharynx, primitive throat, and part of the primitive yolk sac as it becomes enclosed with folding. Midgut and Hindgun: forms the rest of the mature pharynx, and the remainder of the digestive tract.
    • The face and neck begin to develop, as well as the primitive eyes, ears, nose, oral cavity, and jaw areas.
    • MOST CRITICAL PERIOD OF PREGNANCY. Disturbances may give rise to major congenital malformations.

  • Fifth Week

    Fifth Week
    -Circulatory system begin to form in the middle layer (mesoderm).
    - Heart will begin to divide into separate chambers and start pumping blood. The circulatory system is the first organ system to function.
    - Umbilical cord replaces yolk sac.

  • Sixth Week

    Sixth Week
    • Facial features are forming.
    • Brainwaves start, and cerebral vesicles double in size.
    (http://www.ehd.org/dev_article_unit7.php)

  • Seventh Week

    Seventh Week
    • Oral epithelium forming.
    • Ear canals and external structures are forming.
    • Mouth, nose, and ears continue to develop.
    • Limbs begin to develop.
    • Brain and spinal nerves continue to develop.

  • Eighth Week

    Eighth Week
    • Bud stage of mouth development
    • The dental lamina proliferate into buds.
    • The buds eventually develop into tooth germ.

  • Fetal Period

    Fetal Period
    Weeks 9 - Birth
    - Embryo becomes a fetus.
    - Final step of prenatal development.
    - Maturation of individual tissue type, and organs.
    • Tetracycline Stain - acts as a teratogenic drug, where a pregnant woman takes the antibiotic and it has an effect on the child's primary teeth that are developing at the time.