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.
Around 1830, the new kid on the block was caviar processed from the roes of other fish, such as salmon, whitefish, lake herring, carp, cod, lumpfish, spoonbill, paddlefish, even catfish. According to caviar purists, none has the appeal and gentle flavor of the beluga, but other varieties usually are less expensive.