Molecular genetic etiolgy of twin reversed arterial perfusion sequence
Article Abstract:
The twin reversed arterial perfusion condition may occur in identical, rather than fraternal, twin pregnancies. Twin reversed arterial perfusion sequence is a rare condition where one twin develops without a heart and the other twin has a low survival rate due to heart failure and premature birth. Researchers analyzed placenta and fetal tissue from nine twin pregnancies with the complication. DNA patterns were identical for each set of twins, indicating that twins with twin reversed arterial perfusion sequence are identical. Further testing revealed that the twin without the heart may not be the result of polar body fertilization. The reversed perfusion condition may occur when a twin embryo splits late, at least four days after fertilization.
Publication Name: American Journal of Obstetrics and Gynecology
Subject: Health
ISSN: 0002-9378
Year: 1996
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Ultrasonographic measurement of the dividing membrane in twin pregnancy during the second and third trimesters: a reproducibility study
Article Abstract:
Ultrasound measurements of the thickness of the membrane that divides the amniotic sac of twin pregnancies may vary greatly from one ultrasonographer to another and from one ultrasound examination to another. Researchers evaluated the thickness of the dividing membrane using high-resolution ultrasound during the second or third trimesters of 27 twin pregnancies. The most accurate measurements were taken at the junction of placenta and membrane, but even these measurements varied. Ultrasonographers could not distinguish differences in membrane thickness between fraternal and identical twin pregnancies. Measurements of dividing membrane thickness may be more accurate when taken in the first trimester.
Publication Name: American Journal of Obstetrics and Gynecology
Subject: Health
ISSN: 0002-9378
Year: 1995
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Absence of expression of RhD by human trophoblast cells
Article Abstract:
The RhD gene may not be expressed in fetal trophoblast cells. The trophoblast in early embryos are cells which develop into the amnion and other fetal membranes. The RhD gene confers the "positive" or "negative" component of blood type, and can cause immunologic incompatibility between mother and fetus. Researchers examined trophoblast and fetal tissue from 18 pregnancies, and did not find RhD DNA in any sample, even from fetuses with Rh-positive blood. The RhD antigen may not therefore be useful in sorting fetal cells from maternal blood circulation.
Publication Name: American Journal of Obstetrics and Gynecology
Subject: Health
ISSN: 0002-9378
Year: 1998
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