A gland is defined as a secretory organ (i.e., an organ that secretes
substances into the bloodstream or elsewhere in the body). The internal
secretory organs of the body are called endocrine glands. These ductless glands
secrete hormones directly into the blood stream. The glands that are known to
have endocrine function include the pineal, pituitary, thyroid, parathyroid,
thymus, adrenal, pancreas, and gonads (testes and ovaries). Although not
technically glands, other organs of the body are commonly also referred to as
"glandulars" when they are taken as supplements. For example, tissue
extracts of the heart, spleen, prostate, uterus, brain, and other tissues are
often used in so-called "glandular therapy," along with extracts from
pineal, pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, and gonads.
Glandular therapy refers to the use of animal tissues to try to enhance the
function of, or mimic the effect of, the corresponding human tissue.