Direct visualization of retinoic acid in the rat hypothalamus: An immunohistochemical study

► A highly specific antiserum against retinoic acid was developed. ► Retinoic acid was directly visualized for the first time in the mammalian brain. ► Retinoic acid-immunoreactive cell bodies were found in the rat hypothalamus. ► Cell bodies were found in the paraventricular nucleus and above the fornix. ► Retinoic acid shows a very restricted distribution in the rat brain.