Circulatory system?

Question

what part of embryonic tissue becomes circulatory system?

Answer 1

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The endothelial cells are derived from embryonic mesenchyme and should not be regarded as epithelial, but as connective tissue cells. Endothelial cells line the lumina of all the vessels of the blood vascular and lymphatic vascular systems. Endothelial cells lining the blood vessels are very flattened, elongated cells, with elongated nuclei that protrude into the lumina. The total number of endothelial cells in the body is enormous (estimated as 6x1023 cells) and cover a very large surface area (700-1000m2) and in total weigh about 1.5kg.