A morphometric analysis of functionally defined subpopulations of neurons in the paraventricular nucleus of the rat with observations on the effects of colchicine. J Neurosci 9:1375–1388

Two populations of neurons in the paraventricular nucleus of the hypothalamus that have different efferent projections and physiological roles in the regulation of visceral re-sponses were characterized morphologically with a com-bined intracellular filling, retrograde tracer, and immunohis-tochemical method. Neuroendocrine cells were retrogradely labeled by an intravenous injection of Fast blue, and distin-guished from descending neurons that were retrogradely labeled by an injection of fluorogold into the spinal cord. Retrogradely labeled neurons were selectively penetrated and filled intracellularly with Lucifer yellow to visualize de-tailed features of their morphology. Corticotropin-releasing hormone (CRH)-containing neurons were distinguished from other neuroendocrine cells by immunostaining the tissue with an antiserum to rat CRH. Morphometric features of define