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دسته بندی : پاورپوینت
نوع فایل : .ppt ( قابل ویرایش و آماده پرینت )
تعداد اسلاید : 32 اسلاید
قسمتی از متن .ppt :
Multifetal pregnancy
Etiology :
More commonly fertilization of two ova with tow sperm double ovum or fratermal or dizygotic twins
About tow third.
A bout one third as often
One fertilized ovum divided into two similar structures, into a separate individual that we call it a single ovum – monozygotic or Identical twins
Either or both process may be involved in the formation of high number of fetuses .
Genesis of monozygotic twins
If division occurs within first 72 hours before the inner cell mass is formed and the outer layer of blastocyst is not commited to chorion , They will evolve two embryoes ,with diamniotic ,dichorionic monozygotic.
The frecuency 18-36%