['Measurement of nuchal translucency (NT) is a widely used method of screening for chromosomal abnormalities. Increased NT is seen in a diversity of fetal malformations. The mechanism explaining the abnormal fluid accumulation and the transient nature of NT remains unexplained.', 'The nuchal regions of normal and trisomy 16 mouse embryos were examined for (lympho)vascular abnormalities using immunohistochemical markers against lymphatic vessels (LYVE-1) and smooth muscle (1A4) and endothelial (CD34) cells. Additionally, an ultrasonographic study was carried out on 17 human fetuses with an increased NT. Two of these fetuses were examined morphologically.', 'In both abnormal human and mouse specimens, we found a mesenchyme lined cavity within the posterior nuchal region as well as bilaterally enlarged jugular LYVE-1 positive lymphatic sacs. The persistence of jugular lymphatic sacs was also confirmed by ultrasound in 14 human fetuses with increased NT.'] Is increased nuchal translucency associated with jugular lymphatic distension?