A section through the C-3 neural crest and the separation of the tracheoesophageal tube.
Observe:
1. The right venous valve between the sinus venosus and the right atrium.
2. The bifurcation of the trachea into right and left lung buds that are primordia of the right and left bronchial trees.
3. The lateral position of the pericardioperitoneal canal to the lung buds.
4. The right and left common cardinal veins.
5. The four plate regions of the neural tube in the C-3 segment.
Keywords: C-3 neural crest, alar plate, anterior cerebral plexus, basal plate, common cardinal vein, dorsal aorta, floor plate, junction of postcardinal and precardinal veins, left atrium, left lung bud, pericardial cavity, pericardioperitoneal canal, postcardinal vein, preoptic area, primitive esophagus, prosencephalon (telencephalic part), right atrium, right common cardinal vein, right lung bud, right venous valve, roof plate, sulcus limitans, thickened right mesothelium
Source: Atlas of Human Embryos.