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DOI: 10.1016/j.jsgi.2006.02.003 Nuchal Edema and Venous-Lymphatic Phenotype Disturbance in Human Fetuses and Mouse Embryos With Aneuploidy
Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, the Netherlands; Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands; Division of Basic Medical Sciences, Anatomy and Developmental Biology, St. George Hospital Medical School, London, United Kingdom
Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, the Netherlands; Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands; Division of Basic Medical Sciences, Anatomy and Developmental Biology, St. George Hospital Medical School, London, United Kingdom; acgitten{at}lumc.nl Objective: Nuchal edema (NE) is a clinical indicator for aneuploidy, cardiovascular anomalies, and several genetic syndromes. Its etiology, however, is unknown. In the nuchal area, the endothelium of the jugular lymphatic sacs (JLS) develops by budding from the blood vascular endothelium of the cardinal veins. Abnormal distension of the jugular sacs is associated with NE. We hypothesize that a disturbed lymphatic endothelial differentiation and sac formation causes NE. We investigated endothelial differentiation of the jugular lymphatic system in human and mouse species with NE. Methods: Aneuploid human fetuses (trisomy 21; trisomy 18) were compared with euploid controls (gestational age 12 to 18 weeks). Trisomy 16 mouse embryos were compared with wild type controls (embryonic day 10 to 18). Trisomy 16 mice are considered an animal model for human trisomy 21. Endothelial differentiation was investigated by immunohistochemistry using lymphatic markers (prox-1, podoplanin, lymphatic vessel endothelial hyaluronan receptor [LYVE]-1) and en blood vessel markers (neuropilin [NP]-1 and ligand vascular endothelial growth factor [VEGF]-A). Smooth muscle actin (SMA) was included as a smooth muscle cell marker. Results: We report a disturbed venous-lymphatic phenotype in aneuploid human fetuses and mouse embryos with enlarged jugular sacs and NE. Our results show absent or diminished expression of the lymphatic markers Prox-1 and podoplanin in the enlarged jugular sac, while LYVE-1 expression was normal. Additionally, the enlarged JLS showed blood vessel characteristics, including increased NP-1 and VEGF-A expression. The lumen contained blood cells and smooth muscle cells lined the wall. Conclusion: A loss of lymphatic identity seems to be the underlying cause for clinical NE. Also, abnormal endothelial differentiation provides a link to the cardiovascular anomalies associated with NE.
Key Words: Nuchal translucency pathophysiology endothelial differentiation lymphangiogenesis jugular lymphatic sac
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