Furthermore, the present ultrastructural analysis revealed, for the first time, the presence of AT8 and Alz50 positive straight tau filamentous aggregates in female aged 23-month-old, but not in young or middle-age 3xTg-AD mice of the same gender, which are similar to those seen in tangle bearing neurons in the human AD brain. The gene discussed is MAPT; the disease is Alzheimer disease.