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Embryogenesis of fused umbilical arteries in human embryos
Shigehito Yamada1, Junzo Hamanishi, Shozo Tanada
1Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan. shyamada@cac.med.kyoto-u.ac.jp
Objective:
The objective of this study was to elucidate the embryologic basis of fused umbilical arteries in the human.
Study Design:
Twenty-nine human embryo specimens at Carnegie stages 11 through 15 (4-5 weeks after fertilization) were examined histologically, with special reference to the development of umbilical arteries.
Results:
All embryos at Carnegie stage 11 and 12 had fused umbilical arteries, and 66% of Carnegie stage 13 embryos and 29% of Carnegie stage 14 embryos still had the condition. None of the embryos at Carnegie stage 15 or older had fused umbilical arteries, but there were always 2 arteries present in their umbilical cords.
Conclusion:
Our data suggest that (1) a single umbilical artery splits into 2 as the developmental stage of the embryo advances, (2) that fused umbilical arteries represent a remnant of the embryonic phenotype, and (3) that fused umbilical arteries are embryologically distinct from true single umbilical artery.
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