Other organs contain the same sodium/iodine symporter pump that the thyroid gland uses to absorb iodine. Stomach mucosa, mammary glands, and salivary glands have it and can concentrate Iodine almost to the degree that the thyroid does. These tissues also have this pump—the ovaries; thymus gland, seat of the adaptive immune system; skin; choroid plexus in the brain, which makes the cerebrospinal fluid; and in joints, arteries and bone.