ACTH is a segment of a much larger glycoprotein prohormone molecule called proopiomelanocortin (POMC). POMC is synthesized by the corticotrophs of the anterior pituitary, which constitute about 10 percent of the gland.
Caviar harvested from an older fish is the more rare, and more sought after, white caviar. The Beluga sturgeon are primarily found in the Caspian Sea, which is surrounded by Iran, Azerbaijan, Russia, Kazakhstan and Turkmenistan. The other primary source of Beluga sturgeon is the Black Sea near Russia and Romania.
Simply put, caviar is lightly salted roe or fish eggs. Sturgeon roe is considered premium and true caviar. It comes in four varieties -- beluga, sevruga, osetra and ship. The most expensive is beluga caviar ($174/ounce in 2008 pricing) from beluga sturgeon that swim in the Caspian Sea, which is bordered by Russia and Iran. Beluga is characterized by soft, pea-size eggs ranging from pale silver-gray to black.