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.
Even if occasional individuals are caught in some rivers, they do not represent viable populations. Like in all fishes, the amount of caviar (eggs) is linked to the female's size: a female with a length of 1.8 m (6 ft) and weighing 90 kg (200 pounds) can deliver 5 to 15 kg (12 to 40 pounds) of caviar.