Which veins form the intercostal, azygous, and hemi-azygous veins in an embryo?

The correct choice is the supracardinal veins. During embryonic development, supracardinal veins play a key role in forming the venous system, particularly in the thoracic region. They develop from the lateral plate mesoderm and give rise to the intercostal veins, as well as the azygous and hemi-azygous veins.

The intercostal veins are crucial for draining the areas between the ribs, while the azygous system provides an important collateral pathway for venous return from the thoracic and abdominal walls. The hemi-azygous vein helps drain the left side of the lower thorax into the azygous vein.

Understanding the embryological origin of these veins is fundamental in cardiology and perfusion since it underscores how the venous system works and its variations in adults. This knowledge can be critical in surgical procedures or when managing complications related to venous drainage.

Other veins listed, such as the subcardinal, common cardinal, and celiac veins, serve different functions in embryonic vascular development and do not contribute to the formation of the intercostal, azygous, and hemi-azygous veins.