Siamese

Siamese




INTRODUCTION & DEFINITION
This is not a genetic defect but is a mutation during gamesomeness or post zygotic development. Therefore, parents and previous generations do not have that character. Moreover, there are occasions where these Siamese twins can be separated by means of surgery, depending on the nature of the union between individuals, whether they aresymmetrical or asymmetrical. This mutation is congenital; the term simply means "born with it."
Siameses twins are those whose bodies are still together after birth. This tends to occur once in every 200,000 births, being born 50% of cases belong dead and 75% of the Siamese females. The survival rate of conjoined twins is between 5% and 25%. (By: Wikipedia.com - Siamese).
The joints between the twinsare classified according to anatomical region that unites them. They have observed different degrees and different forms of contact, from two well-developed and symmetrical individuals linked by a weak bridge, until the merger of most of the body. Sometimes the twins are of different size and development, so one of them ends up being another parasite, however, this 'monster' dies during birth orshortly thereafter.
There are the classifications of the Siamese:
* Cephalopagus - Anterior union of the upper half of the body with two faces on opposite sides of a conjoined head. The heart is sometimes involved.
* Syncephalus - Joined by the face, containing a single head and two bodies. Syncephalus twins will have one head and a single face with four ears, two on the back of thehead.
* Cephalothoracopagus - Fused from the head to chest. There is only one brain and head (sometimes a rudimentary 2nd face), and they usually share a heart and have fused gastrointestinal tracts. They are non-viable. Also called Epholothoracopagus or Craniothoracopagus.
Janiceps or Janus twins usually share one body with one head and two faces.
* Thoracopagus - United face-to-facefrom the upper thorax down to the umbilicus, with heart involvement, 90% have a shared heart. Four arms, four legs, two pelvises.
* Omphalopagus - Joined face-to-face primarily in the area of the umbilicus, and sometimes involving the lower thorax, but always preserving two distinct hearts. Two pelvis, four arms and four legs.
* Thoraco-Omphalopagus: Combination of thoracopagus andomphalopagus, these twins will be attached from the upper chest to the umbilicus, and will usually share a heart. About 90% of the conjoined thoraco-omphalopagus twins have a common pericardium and 75% have conjoined hearts. Also may have shared livers and gastrointestinal tracts. Four arms and four legs are present.
* Xiphopagus: Joined at the xiphoid process (the smallest of the threedivisions of the sternum, below the gladiolus and manubrium). They are joined roughly from the navel to the lower breastbone. These twins rarely share vital organs aside from the liver.
* Ischiopagus - United from the umbilicus to a large conjoined pelvis with two sacrums and two symphyses pubis. They are joined end-to-end with the spine in a straight line. Four arms, a variable number of legs,and in general, a single external genitalia and a single anus.
* Ischiopagus Dipus - Only two legs are present. Ischiopagus
* Tripus - Three legs are present. Many have only one set of external genitalia. The third
leg can be fused (two legs fused into one), or vestigal (non-functioning).
* Ischiopagus Tetrapus/Quadripus- Four legs are present.
* Omphalo-Ischiopagus- A combination of omphalopagus and ischiopagus, these twins present joined as
* Ischiopagus twins are, but face-to-face with a joined abdomen. Four arms, and a variable number of legs are present.

CAUSES OF THE DISABILITY
There is not still any scientific explanation for this, nor has it been able to show predispositions to twins become conjoined. In the past, said that multiple...