Serum-separating tube Serum-separating tube Serum-separating tubes, also known as serum separator tubes or SSTs, are used in medical clinical chemistry tests requiring blood serum. SSTs are sometimes called "marble-top tubes," "tiger-tops," or "gold-topped tubes", referring to the stoppers which are either gold, red with a gold ring on top, or marbled red and grey. Marble-top tubes are also referred to as "tiger-tops" in some clinics. SPS tubes have a paler colour, sometimes leading confusion; these are known as "yellow tops" not "gold". Trademarked versions include Covidien "Corvac" tubes. They contain a special gel that separates blood cells from serum, as well as
Sweat gland cell are actually pinched off, and disintegrate later to excrete sweat. In both apocrine and eccrine sweat glands, the sweat is originally produced in the gland's coil, where it is isotonic with the blood plasma there. When the rate of sweating is low, salt is conserved and reabsorbed by the gland's duct; high sweat rates, on the other hand, lead to less salt reabsorption and allow more water to evaporate on the skin (via osmosis) to increase evaporative cooling. Secretion of sweat occurs when the myoepithelial cell cells surrounding the secretory glands contract. Eccrine sweat increases the rate of bacterial