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.
In the United States and Canada, any product that is only labeled caviar must come from sturgeon roe. If it contains the roe from any other fish, such as whitefish, it must be labeled with the name of the fish, such as whitefish roe, salmon roe, carp roe, trout roe, etc. The roe of shellfish is also used.