Vasopressin (Antidiuretic Hormone). Vasopressin (arginine vasopressin, AVP; antidiuretic hormone, ADH) is a peptide hormone formed in the hypothalamus, then transported via axons to, and released from, the posterior pituitary into the blood. AVP has two principle sites of action: the kidney and blood vessels.
The Face That Launched 1,000 Awws. Like a tiny feline fashion model, this Persian kitten seems to know how to tilt her head just so. And wow, her eyes are stunning. It's no wonder that the Persian is one of the most popular cat breeds in the United States, according to the Cat Fanciers' Association.
Luckily, plenty of the little guys have also been ranked among the most popular breeds â like Yorkies, Pomeranians and Boston Terriers â and we've added a few more of our favorites to the list. Because size doesn't matter, here are some of the world's most adorable small dog breeds.