harlequin fetus

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fetus

 [fe´tus] (L.)
the developing young in the uterus, specifically the unborn offspring in the postembryonic period, which in humans is from the third month after fertilization until birth. See also embryo. 

The stages of growth of the fetus are fairly well defined. At the end of the first month it has grown beyond microscopic size. After 2 months it is a little over 2.5 cm long, its face is formed, and its limbs are partly formed. By the end of the third month it is 8 cm long and weighs about 30 g; its limbs, fingers, toes, and ears are fully formed, and its sex can be distinguished.

After 4 months the fetus is about 20 cm long and weighs over 200 g. The mother can feel its movements, and usually the health care provider can hear its heartbeat. The eyebrows and eyelashes are formed, and the skin is pink and covered with fine hair called lanugo. By the fifth month the fetus's body is covered with a cheeselike substance (vernix caseosa), which serves to protect it in its watery environment. By the end of the fifth month it is 30 cm long, weighs 450 g, and has hair on its head. At the end of the sixth month it is 35 cm long and weighs 900 g, and its skin is very wrinkled.

After 7 months the fetus is 40 cm long and weighs over 1.3 kg, with more fat under its skin. In the male, the testes have descended into the scrotum. By the end of the eighth month it is 45 cm long, may weigh 2.3 kg, and has a good chance of survival if it is born at that time. At the end of 9 months, the average length of a fetus is 50 cm and the average weight is 3.2 kg. adj., adj fe´tal.
calcified fetus a dead fetus that has become calcified in utero; called also lithopedion.
fetus in fe´tu a small, imperfect fetus, incapable of independent life, contained within the body of another fetus.
harlequin fetus an infant with a severe and dramatic form of congenital ichthyosis, manifested by hyperkeratosis with rigid skin; death usually occurs in the first six weeks of life.
mummified fetus a dead fetus that is dried up and shriveled.
fetus papyra´ceus a dead fetus flattened by being pressed against the uterine wall by a living twin.
parasitic fetus in unequal twins, an incomplete minor fetus attached to a larger, more completely developed fetus (the autosite).

har·le·quin fe·tus

a severe autosomal recessive form of collodion baby in a newborn, usually premature, infant; that is, a form of ichthyosiform erythroderma characterized by encasement of the body in grayish brown, often fissured plaques resembling plates of armor and by grotesque deformity of the face with eclabium and gangrene of terminal phalanges; usually fatal within a few days, although treatment with 13-cis-retinoic acid has been successful in some cases.
Synonym(s): ichthyosis fetalis (1)

harlequin fetus

an infant whose skin at birth is completely covered with thick, horny scales that resemble armor and are divided by deep red fissures. The condition is the most severe form of lamellar exfoliation of the newborn, and the infant is stillborn or dies within a few days of birth.
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Harlequin fetus
A rare autosomal recessive [MIM 242500] disease of infants in which the baby is encased in a hyperkeratotic ‘coccoon’ with deep fissures, accompanied by ectropion. Harlequin ichthyosisis a severe dyskeratosis, caused by defective lipid metabolism; the stratum corneum is up to 30-fold thicker than the stratum malpighii; the stratum granulosa is decreased to a one-cell layer or absent

har·le·quin fe·tus

(hahr'lĕ-kwin fē'tŭs)
Severe form of collodion in a newborn, usually premature; a form of ichthyosiform erythroderma characterized by encasement of the body in grayish brown, often fissured plaques resembling plates of armor, and by grotesque deformity of the face, hands, and feet; usually fatal within a few days.