Prenatal development
The process of growth and development within the womb, in which a single-cell zygote (the cell formed by the combination of a sperm and an egg) becomes an embryo, a fetus, and then a baby. The first two weeks of development are concerned with simple cell multiplication. This tiny mass of cells then adheres to the inside wall of the uterus. The next three weeks see intense cell differentiation, as the cell mass divides into separate primitive systems. At the end of eight weeks, the embryo has taken on a roughly human shape, and is called a fetus. For the next twenty weeks the fetus’ primitive circulatory, nervous, pulmonary, and other systems become more mature, and it begins to move its limbs. At 28 weeks, fat begins to accumulate under the skin, toenails and fingernails appear, and downy hair sprouts on the body and scalp. The fetus may open its eyes periodically. For the remaining weeks of development, the fetus continues to gain weight, and its internal systems reach full development.

Medical dictionary. 2011.

Look at other dictionaries:

  • Prenatal development — This article is about prenatal development of human embryos and fetuses. For other species, see prenatal development (non human). For maternal changes in the prenatal period, see Maternal physiological changes in pregnancy. Prenatal or antenatal… …   Wikipedia

  • Prenatal development (non-human) — Prenatal development is the process in which an immature individual develops before birth. For instance, mammalian prenatal development is the process where an embryo or fetus (or foetus ) gestates during pregnancy, from fertilization until birth …   Wikipedia

  • Development — may refer to: Contents 1 Land use 2 Science and technology 3 Social science …   Wikipedia

  • Prenatal — Occurring or existing before birth. Prenatal care is the regular health care women should receive during pregnancy from an obstetrician or midwife. Prenatal development is the growth and development of a single celled zygote formed by the… …   Medical dictionary

  • Development of the urinary and reproductive organs — The development of the urinary and reproductive organs as a part of the prenatal development, concerns the urinary system and sex organs. The latter is a part of the stages of sexual differentiation. The urinary and reproductive organs are… …   Wikipedia

  • Development of the reproductive system — The development of the reproductive system is a part of prenatal development, and concerns the sex organs. It is a part of the stages of sexual differentiation. Because its location to a large extent overlaps the urinary system, the development… …   Wikipedia

  • Development of the gonads — The prenatal development of the gonads is a part of the development of reproductive system and ultimately forms the testes in males and ovaries in females. They initially develop from the mesothelial layer of the peritoneum. The ovary is… …   Wikipedia

  • Development, Human, National Institute of Child Health and (NICHD) — One of the US National Institutes of Health, NICHD is in a sense the NIH for kids in that it is concerned with child health. The mission of the NICHD is, in formal terms, to support and conduct “research on fertility, pregnancy, growth,… …   Medical dictionary

  • Development of the suspensory ligament of the ovary — The prenatal development of the suspensory ligament of the ovary is a part of the development of the reproductive system. The suspensory ligament originates from the mesonephros, which, in turn, originates from the Wolffian duct: The mesonephros… …   Wikipedia

  • Prenatal cocaine exposure — (PCE) occurs when a pregnant woman uses cocaine and thereby exposes her fetus to the drug. Crack baby was a term coined to describe children who were exposed to crack (cocaine in smokable form) as fetuses; the concept of the crack baby emerged in …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”