I nclude the bone marrow, lymph nodes, spleen, and thymus. Precursor cells in the bone marrow produce lymphocytes. B-lymphocytes (B-cells) mature in the bone marrow. T-lymphocytes (T-cells) mature in the thymus gland. Besides providing a home for lymphocytes (B-cells and T-cells), the ducts of the lymphatic system provide transportation for proteins, fats, and other substances in a medium called lymph.
A book that is made with a stiff paper cover and bound directly to the text block. Many paperback books are converted to hardcover books by mylar binding. Perfect bind
A sandpaper block is a small wooden paddle with strips of sandpaper stapled to one side. It is used to sharpen pencils, charcoal or pastels, or to clean drawing tools, and can be an essential item for an experienced or developing artist.