Twins

[hairless17]

Everything about twins here


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http://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Being_a_twin_means_you_always_have_a_pillow_or_bla nket_handy.jpg/180px-Being_a_twin_means_you_always_have_a_pillow_or_bla nket_handy.jpg

Twins are two offspring resulting from the same pregnancy, either of the same or opposite sex.

The general term for more than one offspring from the same pregnancy (multiple birth) is multiples, for example triplets refers to cases of three offspring from the same pregnancy. A fetus alone in the womb is called a singleton.

Twins are usually, but not necessarily, born in close succession. Due to the limited size of the mother's womb, multiple pregnancies are much less likely to carry to full term than singleton births, with twin pregnancies lasting only 37 weeks on average, 3 weeks less than full term.[1] Since premature births can have health consequences for the babies, twin births are often handled with special precautions.

Twins can either be monozygotic (MZ, colloquially, "identical") or dizygotic (DZ, colloquially, "fraternal"). There are estimated to be approximately 125 million human twins and triplets in the world (roughly 1.9% of the world population), and just 10 million monozygotic twins (roughly 0.2% of the world population and 8% of all twins).[2] The current rate in the United States is 31 twin births per 1,000 women.[3]

The Yoruba, a large west African ethnic group, have the highest rate of twinning in the world.

[hairless17]

Always special

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Thank you too much brothert

[hairless17]

You are welcome

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Types of twins


There are five common variations of twinning. The three most common variations are all dizygotic: (1) male-female twins are the most common result, at about 40 percent of all twins born; (2) female DZ twins (sometimes called sororal twins); (3) male DZ twins. The other variations are monozygotic twins: (4) female MZ twins and (5) (least common) male MZ twins. Male singletons are slightly (about five percent) more common than female singletons. (6) There is also the mirror image variations. This is where the twins develop reverse asymmetric features. About 25% of monozygotic twins are mirror image twins.The rates for singletons vary slightly by country [4]. For example, the sex ratio of birth in the US is 1.05 males/female, while it is 1.07 males/female in Italy. However, males are also more susceptible than females to death in utero, and since the death rate in utero is higher for twins, it leads to female twins being more common than male twins.

Another variety of twins, "polar body twins," (one egg fertilized by two different sperm) is a phenomenon that was hypothesized to occur and may recently have been proven, very rarely, to exist. Polar body twinning would result in "half-identical" twins.[5

[hairless17]

always special

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Always present with these nice words

[hairless17]

I said it always
The good work makes the good comments

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You are right brother

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Dizygotic twins
Dizygotic twins (commonly known as fraternal twins, but also referred to as non-identical twins or biovular twins) usually occur when two fertilized eggs are implanted in the uterine wall at the same time. When two eggs are independently fertilized by two different sperm cells, DZ twins result. The two eggs, or 'ova', form two zygotes, hence the terms 'dizygotic' and 'biovular'.

Dizygotic twins, like any other siblings, have an extremely small chance of having the exact same chromosome profile. Like any other siblings, DZ twins may look similar, particularly given that they are the same age. However, DZ twins may also look very different from each other. They may be different sexes or the same sex. The same holds true for brothers and sisters from the same parents, meaning that DZ twins are simply brothers and/or sisters who happen to have the same age.

Studies show that there is a genetic basis for DZ twinning. However, it is only the female partner that has any influence on the chances of having DZ twins as the male cannot make her release more than one ovum. Dizygotic twinning ranges from six per thousand births in Japan (similar to the rate of monozygotic twins) to 14 and more per thousand in some African countries.[6]

DZ twins are also more common for older mothers, with twinning rates doubling in mothers over the age of 35.[7] With the advent of technologies and techniques to assist women in getting pregnant, the rate of fraternals has increased markedly. For example, in New York City's Upper East Side there were 3,707 twin births in 1995; there were 4,153 in 2003; and there were 4,655 in 2004. Triplet births have also risen, from 60 in 1995 to 299 in 2004.

[hairless17]

Very nice I am so happy to see this

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You are welcome and there is more

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Monozygotic twins

Comparison of zygote development in monozygotic and dizygotic twins. In the uterus, the majority of monozygotic twins share the same placenta and amniotic sac,(although not always) while dizygotic twins do not.Monozygotic twins, frequently referred to as identical twins, occur when a single egg is fertilized to form one zygote (monozygotic) which then divides into two separate embryos. Their traits and physical appearances are not exactly the same; although they have nearly identical DNA[1], environmental conditions both inside the womb and throughout their lives influence the switching on and off of various genes. Division of the zygote into two embryos is not considered to be a hereditary trait, but rather an anomaly that occurs in birthing at a rate of about three in every 1000 deliveries worldwide,[8] regardless of ethnic background. The two embryos develop into fetuses sharing the same womb. When one egg is fertilized by one sperm cell, and then divides and separates, two identical cells will result. If the zygote splits very early (in the first two days after fertilization), each cell may develop separately its own placenta (chorion) and its own sac (amnion). These are called dichorionic diamniotic (di/di) twins, which occurs 20–30% of the time. Most of the time in MZ twins the zygote will split after two days, resulting in a shared placenta, but two separate sacs. These are called monochorionic diamniotic (mono/di) twins.

In about one percent of MZ twinning the splitting occurs late enough to result in both a shared placenta and a shared sac called monochorionic monoamniotic (mono/mono) twins. Finally, the zygote may split extremely late, resulting in conjoined twins. Mortality is highest for conjoined twins due to the many complications resulting from shared organs. Mono/mono twins have an overall in-utero mortality of about 50 percent, principally due to cord entanglement prior to 32 weeks gestation. If expecting parents choose hospitalization, mortality can decrease through consistent monitoring of the babies. Hospitalization can occur beginning at 24 weeks, but doctors prefer a later date to prevent any complications due to premature births. The choice is up to the parents when to start hospitalization. Many times, monoamniotic twins are delivered at 32 weeks electively for the safety of the babies. In higher order multiples, there can sometimes be a combination of DZ and MZ twins.

Mono/di twins have about a 25 percent mortality due to twin-to-twin transfusion syndrome. Di/di twins have the lowest mortality risk at about nine percent, although that is still significantly higher than that of singletons.[9]

Monozygotic twins are genetically identical (unless there has been a mutation in development) and they are always the same sex. On rare occasions, monozygotic twins may express different phenotypes, normally due to an environmental factor or the deactivation of different X chromosomes in monozygotic female twins, and in some extremely rare cases, due to aneuploidy, twins may express different sexual phenotypes, normally due to an XXY Klinefelter's syndrome zygote splitting unevenly [10] [11]). Monozygotic twins look alike, although they do not have the same fingerprints (which are environmental as well as genetic). As they mature, MZ twins often become less alike because of lifestyle choices or external influences. Genetically speaking, the children of MZ twins are half-siblings rather than cousins. If each member of one set of MZ twins reproduces with one member of another set of MZ twins then the resulting children would be genetic full siblings. It is estimated that there are around 10 million monozygotic twins and triplets in the world.

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Identical twins.

[Batoul29]

My sisters are twins
but it's easy to make a difference between them

[hairless17]

They are not real twins

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Sorry but they are...

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My sisters are twins
but it's easy to make a difference between them



My daughters are **Dizygotic twins** and it is too difficult to make a difference

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Zygosity, chorionicity and amniocity

The two types of twins discussed before, monozygotic and dizygotic, are generally referred to as zygocity. Zygocity reflects the genetic type of twins. Two others terms define twin types: chorionity and amniocity. Chorionity refers to the number of chorionic sacs, while amniocity refers to the number of amniotic sacs. The number of chorionic and amnionic sacs can sometimes reveal the zygocity. Monoamniotic twins indicate monozygotic twins. However, two placentas does not provide information about zygocity since monozygotic twins can have two placentas. Chorionicity and amniocity are a result of the division time. Dichorionic twins divide within the first 4 days. Monoamnionic twins divide after the first week.

Complications of twin pregnancy

[ Vanishing twins
Main article: Vanishing twin
Researchers suspect that as many as 1 in 8 pregnancies start out as multiples, but only a single fetus is brought to full term, because the other has died very early in the pregnancy and not been detected or recorded.[22] Early obstetric ultrasonography exams sometimes reveal an "extra" fetus, which fails to develop and instead disintegrates and vanishes. This is known as vanishing twin syndrome.

"]Conjoined twins[/COLOR]
Main article: Conjoined twin
Conjoined twins (or "Siamese twins") are monozygotic twins whose bodies are joined together at birth. This occurs where the single zygote of MZ twins fails to separate completely, and the zygote starts to split after day 13 following fertilization. This condition occurs in about 1 in 50,000 human pregnancies. Most conjoined twins are now evaluated for surgery to attempt to separate them into separate functional bodies. The degree of difficulty rises if a vital organ or structure is shared between twins, such as brain, heart or liver.

http://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Chang-eng-bunker-PD.gif/180px-Chang-eng-bunker-PD.gif

Chimerism===

A chimera is an ordinary person or animal except that some of their parts actually came from their twin or from the mother. A chimera may arise either from monozygotic twin fetuses (where it would be impossible to detect), or from dizygotic fetuses, which can be identified by chromosomal comparisons from various parts of the body. The number of cells derived from each fetus can vary from one part of the body to another, and often leads to characteristic [[mosaicism]] skin colouration in human chimeras. A chimera may be a [[hermaphrodite]], composed of cells from a male twin and a female twin.

Parasitic twins===


Sometimes one twin fetus will fail to develop completely and continue to cause problems for its surviving twin. One fetus acts as a [[parasite]] towards the other.
Sometimes the parasitic twin becomes an almost indistinguishable part of the other, and sometimes this needs to be medically dealt with.


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[hairless17]

Always special
I have nothing to say

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And i have nothing to add but thanx

[hairless17]

Can you tell us about surgery to separate twins

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http://msnbcmedia2.msn.com/j/msnbc/Components/Photos/070606/070606_conjoined_hmed_9a.hmedium.jpg

CLEVELAND - Three-year-old twins Tatiana and Anastasia Dogaru are joined at the head, so they have never seen each other’s face directly.

Surgeons who hope to change that began a series of risky operations on Wednesday aimed at separating the girls. The top of Tatiana’s head is attached to the back of Anastasia’s, and the girls have already beaten the odds by living this long.

The twins, born in Italy to Romanian parents, were under close observation in a pediatric intensive care unit after a full day of surgery, said Janice Guhl, a spokeswoman for University Hospitals’ Rainbow Babies & Children’s Hospital, where the surgeries are being performed.

The hospital didn’t expect to update their condition until Thursday, with a more detailed medical briefing expected Friday.

The entire procedure is expected to take several months. In Wednesday’s operation, surgeons had said they would begin at the girls’ scalps and slowly make a wedge where the twins’ skulls are joined. They planned to remove a rectangular bone flap and reinsert it at the end of the surgery.

The procedure would give neurosurgeons their first real glimpse of the girls’ brains. The medical team practiced the procedure on a model designed from images.

[hairless17]

Thanks a lot
What about the saudi surgeries

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You are welcome,i will put a topic concerning that

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Thanks sister

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RIYADH // For the first time since they entered the world almost four months ago, Alsafa and Almarwa are sleeping in separate beds.
The Moroccan twins, born joined at the abdomen and sharing a liver, were successfully separated here on Saturday by a 17-person Saudi medical team at King Abdulaziz Medical City.

It was the 19th twin separation performed under the supervision of Abdullah al Rabeeah, an internationally recognised expert on separating conjoined twins.

The surgeon said the eight-hour operation on the Moroccan girls was one of the shortest he had ever done. The girls, who together weighed a little more than seven kilograms, were also “the smallest in terms of weight” and among the youngest separated by his surgical team.
Not just us,” said her husband, Saeed al Eessi, 34, an indoor plasterer. “All the Islamic world is happy – the Saudi people, the Moroccan people.”

Although not surgically complicated, Dr Rabeeah said, the procedure was complex with regards to the anaesthesia because Almarwa suffers from congenital heart disease and therefore is at high risk of life-threatening developments.



“Obviously, all of us are extremely excited at how things went,” Dr Rabeeah said at a post-op press conference where he and 11 of his team members, all still in their surgical scrubs, looked happy but tired.

“We’re so happy, I cannot express how happy,” said Aziza Ibn al Ameed, 23, the mother of the twins.

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Alsafa is moved to her own bed following separation surgery from her conjoined twin, Almarwa. Courtesy King Abdulaziz Medical City

[hairless17]

Always ready
Thanks

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I am here to be ready;thank you

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You are welcome
Are there such cases in Algeria ?

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What do you mean ? are you talking about such surgery? 0

[hairless17]

No I am speaking about such cases

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Sorry but i didn't find anything concerning your question

[hairless17]

I will do a search

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And i am waiting thanx

[hairless17]

I made a search , but I think that there are not such cases in Algeria
At least they are not published

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Yes,i did it too but i could not find something ;thanx

[hairless17]

You are welcome