The pregnant drug-dependent woman subjects her developing infant to a host of problems. When assessing the effects of drugs, especially illicit drugs, on newborn infants (neonates) and young children, two factors must be considered: (1) the duration...
Fetal research encompasses a broad array of research activities and potential clinical applications. It is ethically controversial because, although it may yield beneficial results, it involves the human organism at a stage of development where its...
In human development, each limb results from a developmental field. The developmental fields are determined during gastrulation. These limb fields are established by the expression of HOX genes. The expression of the factor Tbx-5 causes the limb to...
The primitive gut tube forms during week four of gestation. It derives from the incorporation of the dorsal part of the definitive yolk sac into the embryo due to embryonic folding. The primitive gut is divided into the foregut, midgut, and hindgut....
Throughout intrauterine life, maternal blood supplies the fetus with oxygen and nutrients, and carries away its wastes. The anatomical structures that allow for such an exchange are the umbilical blood vessels. The umbilical vein transports oxygenated...
The developing fetal heart accounts for a large percentage of the volume of the early thorax. About 20 days after fertilization, the heart develops from the fusion of paired endothelial tubes into a single tube. Heart growth subsequently involves the...
The Carnegie staging system is a method of staging embryonic development that evaluates the embryo's growth and differentiation in 23 stages. It supposes that human development averages 266 days, or 9.5 months. In the early stages of an embryo, a...
The neural system develops from ectodermal cells, the outermost layer of embryonic germ cells. The covering of the neural system and the blood vessels that supply nervous tissue are mesodermal in origin. Immediately after the formation of the embryonic...
In humans, the development of the face and its features such as the nose and palate occurs in the embryonic stage of fetal development. The molecular events that set in motion these developments occur within the first few weeks following fertilization...
Fetus The unborn child from the start of the ninth week after conception to the time of birth. Prenatal development is defined by two stages. The first stage involves the formation of the embryo from the fertilized egg. During this stage, the...
Human being in the womb of the mother, regarded after forty days from conception as possessing a soul; abortion for any purpose other than saving the life of the mother is not permitted; until the baby is born, the life of the mother takes precedence...
(from Latin, fetus: offspring; the American spelling, fetus, has therefore remained true to the original form) A developing organism with the principal organs of the body differentiated and identifiable; before this the organism is known as an EMBRYO;...
The unborn progeny of a mammal whilst still in the womb. In humans the term generally refers to the unborn child after 8 weeks of development. The US spelling is...
A fetus (or foetus or fœtus) is a developing mammal or other viviparous vertebrate, after the embryonic stage and before birth. The plural is fetuses, or sometimes feti. In humans, the fetal stage of prenatal development begins about eight weeks after...
