sentences:  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.On the outer surfaces of these cells are seen delicate transverse lines or markings, which are due to minute elastic fibrillæ arranged in a circular manner around the sinus.