Conjoined Twins

Conjoined twins are identical twins whose bodies are joined in utero. A rare phenomenon, the occurrence is estimated to range from 1 in 50,000 births to 1 in 100,000 births, with a somewhat higher incidence in Southwest Asia and Africa. Approximately half are stillborn, and a smaller fraction of pairs born alive have abnormalities incompatible with life. The overall survival rate for conjoined twins is approximately 25%. The condition is more frequently found among females, with a ratio of 3:1.

Two contradicting theories exist to explain the origins of conjoined twins. The older theory is fission, in which the fertilized egg splits partially. The second and more generally accepted theory is fusion, in which a fertilized egg completely separates, but stem cells (which search for similar cells) find like-stem cells on the other twin and fuse the twins together. Conjoined twins share a single common chorion, placenta, and amniotic sac, although these characteristics are not exclusive to conjoined twins as there are some monozygotic but non-conjoined twins that also share these structures in utero.

The most famous pair of conjoined twins was Chang and Eng Bunker (Thai: อิน-จัน, In-Chan) (1811–1874), Thai brothers born in Siam, now Thailand. They traveled with P.T. Barnum's circus for many years and were billed as the Siamese Twins. Chang and Eng were joined by a band of flesh, cartilage, and their fused livers at the torso. In modern times, they could have been easily separated. Due to the brothers' fame and the rarity of the condition, the term "Siamese twins" came to be used as a synonym for conjoined twins.

Read more about Conjoined Twins:  Types of Conjoined Twins, Separation, Conjoined Twins in History, List of Notable Conjoined Twins

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List of Notable Conjoined Twins - Born 21st Century
... Kendra and Maliyah Herrin, ischiopagus twins separated in 2006 at age 4 ... As Craniopagus twins, the top of Tatiana's head is attached to the back of Anastasias's head ... Tatma (born 2005) was an ischiopagus conjoined twin born in Araria district in the state of Bihar, India ...
A Defense Of Abortion - Criticism
... the conjoined twins objection the relationship between conjoined twins represents a more complete analogy to pregnancy than the relationship between the violinist and the kidney donor ... Because the fatal separation of conjoined twins is immoral, so is abortion ... The pro-choice response would be to state that conjoined twins have equal claims to their shared organs, since they were conceived at the same time, in ...
Craniopagus Twins
... Craniopagus twins are conjoined twins who are fused at the cranium ... congenital abnormalities only accounting for 2-6% of all conjoined twins ... Additionally, conjoined twins are genetically identical and always share the same sex ...
Cat Dog - Premise
... See also List of CatDog episodes The series follows the adventures of CatDog, a conjoined twin hybrid of a cat and dog with two heads (one at either end of its single ... fight each other, and thought that it would be great to make conjoined twins Cat and Dog to see how both of the animals would fare against other things ... The idea of them being conjoined twins came from Hannan watching several news stories on TV about conjoined twins living a normal life conjoined together ...
C. Everett Koop - Career
... Philadelphia, Koop performed groundbreaking surgical procedures on conjoined twins, invented techniques which today are commonly used for infant surgery, and saved the lives ... and participated in the separation of several sets of conjoined twins whose condition other physicians at the time considered hopeless ... recognition in 1957 by the separation of two female pygopagus infants (conjoined at the buttocks) and then, again, in 1974 by the separation of two ischiopagus twins (conjoined ...

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