Fig. 2.

Immunohistochemical analysis of tau isoforms and their phosphorylation status in cat brains. Immunohistochemistry for 3-repeat tau (RD3), 4-repeat tau (RD4), and hyperphosphorylated-tau (AT8) in the developing cat (Fetus, case No. 1 shown in Table 1), adult cat (4 years (yrs) old, case No. 7), and aged cat (19 yrs old, case No. 22) brains. Only the 3-repeat tau isoform is expressed in the fetal cat brain, whereas both 3-repeat and 4-repeat tau isoforms are expressed in the developed cat brains. Abundant AT8-positive hyperphosphorylated tau aggregates are observed in the hippocampus and entorhinal cortex of the aged cat brain. Bar = 5 mm