The temporal evolution of @entity75 . II. Light- and electron-microscopic findings in the hippocampal gyrus and subiculum of the XXXX .

@entity63 @entity75 @entity1249 @entity1251 @entity35 @entity528 @entity2383
Part I of this paper has documented the evolution of dark neurons into acidophilic neurons in the superficial laminae as well as the reversion of dark neurons to normal neurons in the deep laminae of the cerebral cortex in @entity75 . The present study describes the temporal evolution of @entity75 in the hippocampus. The evolution of dark neurons to acidophilic neurons was confirmed in this brain region. Four additional problems were addressed: Firstly, delayed @entity528 was looked for, and was found to occur in areas of @entity1249 undergoing mild damage. However, it was not preceded by a morphological free interval, had ultrastructural characteristics distinct from delayed @entity528 in @entity63 , and hence should be considered a distinct phenomenon. Secondly, the gradient in the density of @entity528 in the @entity35 hippocampal pyramidal cell band was exploited to test the hypothesis that a more severe insult causes a more rapid evolution of neuronal changes. This was found to be the case, with a temporal spectrum in the timing of @entity528 : Necrosis occurred already after 2 h medially in the subiculum, and was delayed by up to several weeks laterally in @entity1249 . Thirdly, the almost universal sparing of @entity1251 pyramidal neurons after 30 min hypoglycemic isoelectricity was exploited to address the question of whether reactive changes, which could with certainty be deemed reversible, occur in @entity1251 . @entity2383 was seen in these cells, and was found to be recoverable. No reactive changes of the type previously described following ischemic insults were observed. Fourthly, the astrocytic and vascular response of the tissue was studied. A sequence of astrocytic changes representing structural and probably metabolic activation of astrocytes was seen, consisting of morphological indices of increased turnover of cellular components. Capillaries demonstrated endothelial pits, vesicles, and prominent microvilli hours to days after recovery. The results demonstrate that, in the hippocampal gyrus as in other brain regions, @entity75 is distinct from @entity75 and likely has a different pathogenesis.
