Cardiac defects, nuchal edema and abnormal lymphatic development are not associated with morphological changes in the ductus venosus.

BACKGROUND: In human fetuses with cardiac defects and increased nuchal translucency, abnormal ductus venosus flow velocity waveforms are observed. It is unknown whether abnormal ductus venosus flow velocity waveforms in fetuses with increased nuchal translucency are a reflection of altered cardiac function or are caused by local morphological alterations in the ductus venosus. AIM: The aim of this study was to investigate if the observed increased nuchal translucency, cardiac defects and abnormal lymphatic development in the examined mouse models are associated with local changes in ductus venosus morphology. STUDY DESIGN: Mouse embryos with anomalous lymphatic development and nuchal edema (Ccbe1(-/-) embryos), mouse embryos with cardiac defects and nuchal edema (Fkbp12(-/-), Tbx1(-/-), Chd7(fl/fl);Mesp1Cre, Jarid2(-/-NE+) embryos) and mouse embryos with cardiac defects without nuchal edema (Tbx2(-/-), Fgf10(-/-), Jarid2(-/-NE-) embryos) were examined. Embryos were analyzed from embryonic day (E) 11.5 to 15.5 using markers for endothelium, smooth muscle actin, nerve tissue and elastic fibers. RESULTS: All mutant and wild-type mouse embryos showed similar, positive endothelial and smooth muscle cell expression in the ductus venosus at E11.5-15.5. Nerve marker and elastic fiber expression were not identified in the ductus venosus in all investigated mutant and wild-type embryos. Local morphology and expression of the used markers were similar in the ductus venosus in all examined mutant and wild-type embryos. CONCLUSIONS: Cardiac defects, nuchal edema and abnormal lymphatic development are not associated with morphological changes in the ductus venosus. Ductus venosus flow velocity waveforms most probably reflect intracardiac pressure.

Absence of an anatomical origin for altered ductus venosus flow velocity waveforms in first-trimester human fetuses with increased nuchal translucency.

OBJECTIVE: To perform a morphological evaluation of the ductus venosus, heart and jugular lymphatic sac (JLS) in first-trimester human fetuses with normal and abnormal ductus venosus flow velocity waveforms (DV-FVWs) and normal and increased nuchal translucency (NT). METHOD: Postmortem examination was performed on fetuses with increased NT or structural malformations with previous NT and DV-FVW measurements. Ductus venosus morphology was examined using markers for endothelium, smooth muscle actin (SMA), nerves and elastic fibers. Fetal hearts were studied by microscopy. The nuchal region was analyzed using markers for lymphatic vessels, endothelium, SMA and nerves. RESULTS: Two trisomy 21 and two trisomy 18 fetuses with increased NT and abnormal DV-FVWs were analyzed. As a control, one euploid anencephalic fetus with normal NT, cardiac anatomy and DV-FVWs was examined. Similar endothelial and SMA expression was observed in the ductus venosus in all fetuses. Nerve and elastic fiber expression were not detected. Three trisomic fetuses showed cardiac defects, one trisomic fetus demonstrated normal cardiac anatomy. The JLS was abnormally enlarged or contained red blood cells in all trisomic fetuses. The control fetus showed a normal JLS. CONCLUSION: Abnormal DV-FVWs are not justified by alterations in ductus venosus morphology. DV-FVWs most probably reflect intracardiac pressure. © 2016 John Wiley & Sons, Ltd.

Increased nuchal translucency origins from abnormal lymphatic development and is independent of the presence of a cardiac defect.

OBJECTIVE: To assess whether cardiac failure, because of cardiac defects, and abnormal jugular lymphatic development are involved in nuchal edema (NE) - the morphological equivalent of increased nuchal translucency - in various euploid mutant mouse models. METHOD: Mouse embryos with lymphatic abnormalities and NE (Ccbe1(-/-)), with cardiac defects and NE (Fkbp12(-/-), Tbx1(-/-), Chd7(fl/fl);Mesp1Cre, Jarid2(-/-NE+)) and with cardiac malformations without NE (Tbx2(-/-), Pitx2(-/-), Fgf10(-/-), Jarid2(-/-NE-)) were examined. Embryos were analyzed from embryonic day 11.5 to 15.5. Markers for lymphatic vessels, endothelium, smooth muscle cells and nerves were used to study the nuchal region. Hematoxylin-Azophloxine staining was performed to examine cardiac morphology. RESULTS: Mouse embryos with lymphatic abnormalities and NE (Ccbe1(-/-)) showed no formation of the jugular lymphatic sac but normal cardiac morphology. In mouse embryos with cardiac defects and NE (Fkbp12(-/-), Tbx1(-/-), Chd7(fl/fl);Mesp1Cre, Jarid2(-/-NE+)) enlarged jugular lymphatic sacs or large nuchal cavities within the NE were found. In mouse embryos with a cardiac malformation without NE (Tbx2(-/-), Pitx2(-/-), Fgf10(-/-), Jarid2(-/-NE-)) normal jugular lymphatic sacs were observed. CONCLUSION: NE consistently coincides with abnormal jugular lymphatic development in euploid mouse embryos, independent of cardiac anatomy. NE is unlikely to be caused by temporary cardiac failure solely because of a cardiac defect.

Involvement of neurons and retinoic acid in lymphatic development: new insights in increased nuchal translucency.

OBJECTIVE: Increased nuchal translucency originates from disturbed lymphatic development. Abnormal neural crest cell (NCC) migration may be involved in lymphatic development. Because both neuronal and lymphatic development share retinoic acid (RA) as a common factor, this study investigated the involvement of NCCs and RA in specific steps in lymphatic endothelial cell (LEC) differentiation and nuchal edema, which is the morphological equivalent of increased nuchal translucency. METHODS: Mouse embryos in which all NCCs were fluorescently labeled (Wnt1-Cre;Rosa26(eYfp) ), reporter embryos for in vivo RA activity (DR5-luciferase) and embryos with absent (Raldh2(-/-) ) or in utero inhibition of RA signaling (BMS493) were investigated. Immunofluorescence using markers for blood vessels, lymphatic endothelium and neurons was applied. Flow cytometry was performed to measure specific LEC populations. RESULTS: Cranial nerves were consistently close to the jugular lymph sac (JLS), in which NCCs were identified. In the absence of RA synthesis, enlarged JLS and nuchal edema were observed. Inhibiting RA signaling in utero resulted in a significantly higher amount of precursor-LECs at the expense of mature LECs and caused nuchal edema. CONCLUSIONS: Neural crest cells are involved in lymphatic development. RA is required for differentiation into mature LECs. Blocking RA signaling in mouse embryos results in abnormal lymphatic development and nuchal edema.