Vascular anastomoses in dichorionic diamniotic-fused placentas.
ABSTRACT A case of fetal twin-to-twin cytomegalovirus infection through a dichorionic diamniotic (DiDi)-fused placenta prompted our search for possible vascular anastomoses in this type of placenta. This case and three additional DiDi-fused placentas were studied with gross (macro) sections and a three-dimensional (3D) stereomicroscopic technique. Two twins were dizygotic (they differed in gender and blood groups) and the other two were probably monozygotic. Macrosections and 3D-image analysis demonstrated side-to-side connections between small subchorionic vessels. These findings demonstrate that vascular anastomoses are present in DiDi-fused placentas.
- Fetal and pediatric pathology 01/2010; 29(2):81-8. · 0.36 Impact Factor
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ABSTRACT: The analysis of monozygotic twins (MZ) concordant for neurofibromatosis type 1 (NF1) has indicated that genetic factors exert a major influence on the clinical variability (e.g. the number of café-au-lait spots and/or neurofibromas) evident in this disease. Here, we report on a pair of monozygotic, dichorionic twins who are phenotypically discordant with respect to NF1. Whereas DNA sequence analysis indicated somatic mosaicism for the NF1 nonsense mutation, c.4108C>T (p.Q1370X), in the affected twin II/1, this lesion was apparently absent in his unaffected brother. The observation of heterozygosity for flanking SNP and microsatellite markers rendered it most unlikely that the observed mosaicism with normal cells was due to mutation reversion brought about either by gene conversion or mitotic recombination. Instead, we conclude that the twinning event, which would have taken place within three days post-fertilization, must have preceded the c.4108C>T mutation which is therefore predicted to have occurred during the blastocyst stage, leading to somatic mosaicism with normal cells lacking the mutation. This is the first reported case of monozygotic twins discordant for NF1 in whom mosaicism for a postzygotic NF1 gene mutation has been observed in the affected but not the unaffected twin.Human Mutation 06/2011; 32(6):E2134-47. · 5.21 Impact Factor
Chapter: Human Embryogenesis04/2012; , ISBN: 978-953-51-0466-7