Immunohistochemistry of AD (A,B) and aging Tg2576 (C–P) brains. Serial sections of temporal cortex from AD brain and Tg2576 brains were labeled with BA-27, which is specific for Aβ40, or BC-05, which is specific for Aβ42. The age (months) of the Tg2576 brains is shown above the serial sections stained with BA-27 (top panel) and BC-05 (bottom panel). Aβ40 (stained by BA-27) and Aβ42 (stained by BC-05) are detected as dense microdeposits from 8 (M, N) to 12 (I, J) months. From 15 to 23 months (C–H), Aβ deposits increase in number and size and are detected both as cored plaques labeled by both BC-05 and BA-27 and as diffuse plaques, which are selectively labeled by BC-05. Sections are 5-μm-thick. Scale bar, 15 μm.