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Fetus in fetu (or foetus in foetu) is a rare developmental abnormality in which a mass of tissue resembling a fetus forms inside the body of its twin. An early example of the phenomenon was described in 1808 by George William Young. [ 1] There are two hypotheses for the origin of a "fetus in fetu". One hypothesis is that the mass begins as a ...
A lithopedion. This highly unusual specimen remained in the abdomen of a woman for 2 years. A lithopedion ( also spelled lithopaedion or lithopædion; from Ancient Greek: λίθος "stone" and Ancient Greek: παιδίον "small child, infant"), or stone baby, is a rare phenomenon which occurs most commonly when a fetus dies during an ...
Embryonic development in the human, covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a fetus. The eight weeks have 23 stages. Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or ...
Dermoid cysts develop during pregnancy. They occur when skin cells and things like hair, sweat glands, oil glands or fatty tissue get trapped in the skin as a baby grows in the womb. Dermoid cysts are present at birth (congenital) and are common. It can be months or years before a dermoid cyst is noticed on a child because the cysts grow slowly.
Pathophysiology. Teratomas belong to a class of tumors known as nonseminomatous germ cell tumor. All tumors of this class are the result of abnormal development of pluripotent cells: germ cells and embryonal cells. Teratomas of embryonic origin are congenital; teratomas of germ cell origin may or may not be congenital.
The fetal membranes separate maternal tissue from fetal tissue at a basic mechanical level. The fetal membrane is composed of a thick cellular chorion covering a thin amnion composed of dense collagen fibrils. The amnion is in contact with the amniotic fluid and ensures structural integrity of the sac due to its mechanical strength.
Some degree of weight gain is expected during pregnancy. The enlarging uterus, growing fetus, placenta, amniotic fluid, normal increase in body fat, and increase in water retention all contribute weight gain during pregnancy. The amount of weight gain can vary from 5 pounds (2.3 kg) to over 100 pounds (45 kg).
Sexual differentiation in humans. The human Y chromosome showing the SRY gene which codes for a protein regulating sexual differentiation. Sexual differentiation in humans is the process of development of sex differences in humans. It is defined as the development of phenotypic structures consequent to the action of hormones produced following ...