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.
When it comes to caviar, there is no better or worse - it's all a matter of personal preference. But some caviars have a more robust taste of the sea, such as Siberian or Shassetra Caviars. Others have a milder, nuttier flavor, especially Ossetra and Transmontanus.