RT Journal Article
SR Electronic
T1 Histochemical Characterization and Functional Significance of the Hyperintense Signal on MR Images of the Posterior Pituitary
JF American Journal of Neuroradiology
JO Am. J. Neuroradiol.
FD American Society of Neuroradiology
SP 1079
OP 1083
VO 9
IS 6
A1 John Kucharczyk
A1 Walter Kucharczyk
A1 Isabelle Berry
A1 Jack de Groot
A1 William Kelly
A1 David Norman
A1 T. H. Newton
YR 1988
UL http://www.ajnr.org/content/9/6/1079.abstract
AB MR imaging of the pituitary fossa characteristically shows a well-circumscribed area of high signal intensity in the posterior lobe on T1-weighted images. We used a combination of high-field MR, electron microscopy, and histologic techniques in experimental animals to determine whether the hyperintensity of the posterior lobe might be functionally related to hormone neurosecretory processes, and to attempt to establish its chemical nature. Histologic sections of a dog's pituitary gland processed with lipid-specific markers showed intense staining in the posterior lobe but not in the anterior lobe, thus documenting the location of fat in the posterior pituitary. Administration of vasoactive drugs known to influence vasopressin secretion to anesthetized cats produced changes in the volume of high-intensity signal in the posterior pituitary. Subsequent electron microscopy showed a significant increase in posterior lobe glial cell lipid droplets and neurosecretory granules in dehydration-stimulated cats. The data suggest that the pituitary hyperintensity represents intracellular lipid signal in the glial cell pituicytes of the posterior lobe or neurosecretory granules containing vasopressin. The volume of the signal may, in turn, reflect the functional state of hormonal release from the neurohypophysis.