After centrifugation, one can distinguish a layer of clear fluid (the plasma), a layer of red fluid containing most of the red blood cells, and a thin layer in between. Composing less than 1% of the total volume of the blood sample, the<unk>  (so-called because it is usually<unk> in hue), contains most of the white blood cells and platelets. The<unk>  is usually whitish in color, but is sometimes green if the blood sample contains large amounts of neutrophils, which are high in green-colored myeloperoxidase. The layer beneath the<unk>  contains granulocytes and red blood cells. The<unk>  is commonly used for DNA extraction, with white blood cells providing approximately 10 times more concentrated sources of nucleated cells. They are extracted from the blood of mammals because mammalian red blood cells are anucleate and do not contain DNA. A common protocol is to store<unk>  specimens for future DNA isolation and these may remain in frozen storage for many years. Some refer to the<unk>  when separating cells by Ficoll density gradients. This usage of the expression<unk>  is incorrect.
Buffy coat
White coat
Moon face
Light skin
Spray-on skin
Sling 
Nipple pigmentation
Green nails