sentences:  The blood is collected from the interstices of the tissue by the rootlets of the veins, which begin much in the same way as the arteries end.The connective-tissue corpuscles of the pulp arrange themselves in rows, in such a way as to form an elongated space or sinus.They become elongated and spindle-shaped, and overlap each other at their extremities, and thus form a sort of endothelial lining of the path or sinus, which is the radicle of a vein.