prenatal development

Introduction
Pre-embryonic and embryonic development
- Fertilization
- Cleavage and blastulation
- Implantation and placentation
  - Implantation
  - Placentation
- Extra-embryonic membranes
  - Yolk sac
  - Amnion
  - Allantois
  - Umbilical cord
- Formation of the three primary germ layers
- Growth and differentiation
- Embryonic acquisition of external form
  - Development between the second and fourth weeks
  - Developmental changes in the fifth to eighth weeks
Fetal development
Development of organs
- Ectodermal derivatives
  - Integumentary system
  - Mouth and anus
  - Central nervous system
    - Brain
    - Spinal cord
  - Peripheral nervous system
    - Spinal nerves
    - Cranial nerves
  - Autonomic nervous system
  - Sense organs
    - Olfactory organ
    - Gustatory organ
    - Eye
    - Ear
- Mesodermal derivatives
  - Skeletal system
    - Axial skeleton
    - Appendicular skeleton
    - Articulations
  - Muscular system
  - Vascular system
    - Blood vessels
    - Lymphatic vessels
    - Heart
  - Urinary system
  - Genital system
    - Gonads
    - Genital ducts
    - External genitalia
  - Coelom
- Endodermal derivatives
  - Pharynx
  - Digestive tube
  - Major glands
  - Respiratory system
    - Nasal cavity
    - Larynx, trachea, and lungs
Abnormal development
- Multiple births
- Fetal deviations
- Teratology

References & Edit History Quick Facts & Related Topics

Images & Videos

human fetus; prenatal development

Close-up illustration of a human fetus inside the womb, showing the developing baby holding the umbilical cord in a warm, reddish environment.

embryos of different animals

Diagram showing early human embryo development. The top row illustrates ovum cleavage from a single cell to a morula. The bottom row shows blastocyst formation and implantation, with labeled cell structures.

Three labeled cross-section diagrams show the development of a human embryo implanted in the uterine lining at 7.5, 13, and 23 days, highlighting structures such as the embryonic disk, amniotic cavity, yolk sac, trophoblast, and chorion.

Diagram showing three stages in early human embryonic development: the growth of the amnion at 23 days, a back view of an embryo at 21 days with the amnion cut open revealing neural structures, and a side view at 23 days with the yolk sac and amnion cut open, highlighting the heart, brain, spinal cord, and umbilical blood vessels.

Two labeled diagrams show the human embryonic disk at 18 days: a three-quarter view and a cross-section, highlighting structures such as the amniotic cavity, yolk sac, embryonic shield, body stalk, and layers including ectoderm, mesoderm, and endoderm.

formation of the neural tube in prenatal development

Diagram showing human embryological and fetal development in three stages: at six weeks, the embryo is enclosed within halved amnion, chorion, and uterus; another view at six weeks highlights the formation of the umbilical cord; at three months, the fetus is shown within the halved amnion, chorion, and uterus, with the placenta and umbilical cord labeled.

Related Questions

human fetus; prenatal development — human fetus; prenatal development An ultrasound image of a human fetus.

prenatal development

physiology

Also known as: antenatal development

Written by

Leslie B. AreyAll

Fact-checked by

Britannica Editors

prenatal development, in humans, the process encompassing the period from the formation of an embryo, through the development of a fetus, to birth (or parturition). The human body, like that of most animals, develops from a single cell produced by the union of a male and a female gamete (or sex cell). This union marks the beginning of the prenatal period, which in humans encompasses three distinct stages: (1) the pre-embryonic stage, the first two...

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