express nitric oxide synthase (NOS)-like molecules. The presence of NOS-like molecules was demonstrated by means of
NADPH-diaphorase (NADPHd) staining and NOS immunohistochemistry. In the caudal spinal cord, NOS-positive neurosecretory cell bodies and neurosecretory fibers were observed. In addition, NOS-positive structures were found in the urophysis which
correspond to neurosecretory axon terminals. Cellular co-localization of NOS and ovine corticotropin-releasing factor (oCRF)
immunoreactivities confirmed that the NOS-positive structures belong to the caudal neurosecretory system. The present results
suggest that NO may participate in the caudal neuroendocrine function.