Step I Twinning

[Cliff Huxtable]

So what are the outcomes of the 3 possible twinning types?

Dichorionic, Diamnionic = ?

Monochorionic, Diamniotic = ?

Monochorionic, Monoamnionic = Conjoined twins

 

[calespine]

monozygotic twins can result from any of the three

 

[rahulb]

So what are the outcomes of the 3 possible twinning types?

Dichorionic, Diamnionic = ?

Monochorionic, Diamniotic = ?

Monochorionic, Monoamnionic = Conjoined twins

Dichorionic, Diamnionic = fraternal or identical

Monochorionic, Diamniotic = identical

Monochorionic, Monoamnionic = identical or conjoined

 

[Cliff Huxtable]

Exactly what I needed, thanks!

 

[defcon8]

So what are the outcomes of the 3 possible twinning types?

Dichorionic, Diamnionic = ?

Monochorionic, Diamniotic = ?

Monochorionic, Monoamnionic = Conjoined twins

Dichorionic, diamniotic twinning occurs either by fertilization of 2 ova or by splitting of the fused embryo before 72 hours after fertilization. These both result in a separate placenta and amniotic sac. the former producing genetically distinct twins and the latter forming identical twins.

The chorion is fully formed at day 3 and thus splitting of the embryo subsequent to this forms a monochorionic, diamniotic twin. these are identical twins sharing a placenta, each with their own amniotic sacs.

At day 8, the amnion is fully formed and thus only monochorionic, monoamniotic twins can be formed from splitting of the embryo subsequent to this. These are identical twins sharing the same amniotic sac and placenta.

After day 12, splitting of the embryo causes conjoined twinning as the embryonic disk is fully formed.

No twinning occurs after day 15.

Hope this helps.