Fig. 2

Pretangle neurons in the hippocampal pyramidal layer of the 36-year-old monkey. Tau IR with AT8 a and that with RD4 b were granular and diffuse in the neuronal cytoplasm and dendrites, rarely organized into neurofibrillary tangles. Argyrophilia with Gallyas silver impregnation was limited to a few neurons (c, arrowhead). None of these neurons exhibited fibrillary structures in their cytoplasm. In contrast, numerous neurofibrillary tangles were stained by Gallyas silver impregnation in the CA1 of a 94-year-old male with AD (d, arrowheads). Scale bar, 50 μm