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2 Pups 1 Sac Different Sex


Kinkykaters
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Hi my bitch just had a litter of 14 pups and 2 of them were in one sac, 1 placenta..the poor girl yelped so loud!. I have heard of this before but they are opposite sex! I wouldn't of believe it if some one had told me about this but i seen them come out with my own eyes! they look identical they even seem to have a strange bond already... always away from the other pups but cuddling eachother! has any one else seen or heard of this??

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In extremely rare cases, identical twins have been born with opposite sexes (one male, one female). In these cases, identical twin boys are conceived, but, during the twinning process, one twin loses a Y chromosome (boys have chromosome type XY while girls have XX). Without a Y chromosome to trigger the production of male sex hormones , this fetus develops as a girl by default, but a girl with only one X chromosome (chromosome type XO). The co-twin is unaffected, and develops as a boy as normal.

I read this about humans but i haven't been able to find any thing about it with dogs

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they cant be indentical twins though.

No, I would think the mere fact that one is male and one is female would automatically go against the definition of "identical" :laugh:

I only put that comment there because the heading says they're identical. But it seems the OP has further information so perhaps you and I are wrong. :shrug:

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they cant be indentical twins though.

No, I would think the mere fact that one is male and one is female would automatically go against the definition of "identical" :laugh:

I only put that comment there because the heading says they're identical. But it seems the OP has further information so perhaps you and I are wrong. :shrug:

I know sacs can fuse together becoming "one", which could be how you get un-identical twins.

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My understanding of the difference between identical and unidentical was always that identical is one fertilized egg split and unidentical is two eggs/two sperm, but in the one sac. I have not done any recent research though.

The pups I have known of coming out of the one sack and have been different gender, I have no idea if they were one or two eggs.

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In extremely rare cases, identical twins have been born with opposite sexes (one male, one female). In these cases, identical twin boys are conceived, but, during the twinning process, one twin loses a Y chromosome (boys have chromosome type XY while girls have XX). Without a Y chromosome to trigger the production of male sex hormones , this fetus develops as a girl by default, but a girl with only one X chromosome (chromosome type XO). The co-twin is unaffected, and develops as a boy as normal.

I read this about humans but i haven't been able to find any thing about it with dogs

Just a little :offtopic: but someone close to me was born a twin, both boys, & the other boy died a few days later. The surviving twin grew up & had a family of his own. In his late fifties, he announced that all his life he had thought he was a girl & consequently had a sex change & is now a girl. We had twin calves born once...a boy & a girl. The heifer turned out to be sterile & evidently this is quite common in twin calves...wonder if it is the same with identical twin pups.

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In extremely rare cases, identical twins have been born with opposite sexes (one male, one female). In these cases, identical twin boys are conceived, but, during the twinning process, one twin loses a Y chromosome (boys have chromosome type XY while girls have XX). Without a Y chromosome to trigger the production of male sex hormones , this fetus develops as a girl by default, but a girl with only one X chromosome (chromosome type XO). The co-twin is unaffected, and develops as a boy as normal.

I read this about humans but i haven't been able to find any thing about it with dogs

so do the girls grow up to be 'full' girls with only one X chromosome?

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In extremely rare cases, identical twins have been born with opposite sexes (one male, one female). In these cases, identical twin boys are conceived, but, during the twinning process, one twin loses a Y chromosome (boys have chromosome type XY while girls have XX). Without a Y chromosome to trigger the production of male sex hormones , this fetus develops as a girl by default, but a girl with only one X chromosome (chromosome type XO). The co-twin is unaffected, and develops as a boy as normal.

I read this about humans but i haven't been able to find any thing about it with dogs

so do the girls grow up to be 'full' girls with only one X chromosome?

I was wondering about that too. Do they have any complications?

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In extremely rare cases, identical twins have been born with opposite sexes (one male, one female). In these cases, identical twin boys are conceived, but, during the twinning process, one twin loses a Y chromosome (boys have chromosome type XY while girls have XX). Without a Y chromosome to trigger the production of male sex hormones , this fetus develops as a girl by default, but a girl with only one X chromosome (chromosome type XO). The co-twin is unaffected, and develops as a boy as normal.

I read this about humans but i haven't been able to find any thing about it with dogs

so do the girls grow up to be 'full' girls with only one X chromosome?

I was wondering about that too. Do they have any complications?

In humans individuals with XO (called Turner Syndrome) are sterile as the sex organs do not mature at adolescence.

I personally find it hard to believe that 2 pups could be identical twins but opposite sexes. "losing" a chromosome after fertilisation and blastocyst splitting (i.e. into twins) seems highly irregular and I can't see how that would work.

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As a result of her genetic abnormality, the girl will suffer from Turner syndrome, which is distinguishable by short stature, folds of skin at the neck, abnormal development of secondary sexual characteristics, and an intellectual deficit known as space-form blindness . Turner syndrome can occur in any birth (including singletons, fraternal female twins, or identical female twins), so an individual with Turner syndrome is not automatically a twin. Turner syndrome occurs in about 1 in 10,000 of all births, but cases of mixed sex identical twins are much rarer—only three cases have been documented.

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