Spontaneous intracrania.l hemorrhages (so called, subdural hemorrhages) were produced in suckling
mice (32 of the ICR strain and 100 of the non ICR strain) by injection of 6-aminonicotinamide (6-AN). The animals were sacrificed under ketamine anesthesia between Day 9 and 38 postinjection for
morphological and histological study.
The following observations were made:
1. Spontaneous intracranial hemorrhages were developed from Day 21 postinjection of 6-AN (mostly from Day 28 to 38 postinjection) and those incidences were 46.9% of the ICR strain comparing to 18.8% of the non ICR strain mice.
2. On light microscopic observation, the dura was divided into several cell layers, forming multiple compartments, in which blood clots were found in most cases. The innermost cell layer of dura, ducal border cells, lining organized hematoma at it´s inner surface could be identifiable. The blood clots were also found in subpial space in some cases, but not in subarachnoidal space.
3. Electron microscopic findings of inner membranes of organized hematoma showed layering´ of arachnoidal fibroblasts and cytoplasmic protrusions from proliferated capillary endothelial cells with tight junction between intercellular collagen fibers and macrophage.
Therefore, it was thought that site of so called, subdural hemorrhage in this experiment would be intradural or subpial.
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