Friday, November 2, 2007

Twins


Twins

Kembar Seiras

Twins are two children produced in a single pregnancy. Although they are by far the most common of multiple births, twins still excite a great deal of wonder from parents and outsiders alike.

Twin born at almost the same time to the same mother. Twins occur about once in every 50 to 150 births. There are two types:
• Fraternal or dizygotic twins and identical
• Monozygotic twins

Fraternal Twins
In a normal pregnancy only one ovum or egg is fertilized. However, if two ova are fertilized at the same time, fraternal or non-identical twins will be born. These twins may be of the same or different sexes, and can be dissimilar to each other as any pair of siblings. This is because they grow from two separate egg cells fertilized at the same time.The tendency to give birth to fraternal twins is inherited, especially through the mother’s side.

• Non-identical ( fracternal) twins result from two separate eggs that are fertilized at the same time by two separate sperm; each twin develops its own placenta.


• Identical twins result when a single egg is fertilized and later divides. These twins usually share the same placenta unless the cells separate at an early stage of development.

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