Cytochemical calcium localization in hypothalamo-neurohypophysial system of rats after ischemia. Preliminary...

Using the oxalate-pyroantimonate technique ultrastructural localization of Ca2+ was determined in the nucleus supraopticus, the nucleus paraventricularis and in the neurohypophysis after complete cerebral ischemia. We observed an increased calcium accumulation in mitochondria of some neurons. Calcium precipitate was also found in vesicles, in cytoplasm of neurons and their swollen dendritic processes. Abundant Ca2+ precipitate occurred in synaptic vesicles and within synaptic cleft. It was present between disjuncted lamellae of the myelin sheath in profiles of myelinated axons present in neuropil. Diffuse precipitate was visible in the cytoplasm of pituicytes, as well as in microvesicles in the neurohypophysis. The possible role of calcium in ischemia is briefly discussed.