Brain immune cell density dipped then rose in macaques
A tissue study of 15 female rhesus macaques, from late gestation to 32.4 years, found lower density after birth and higher density later.
Limit: Only 15 females represented the full age range
Edited by Boris Djordjevic · AgingResearch.News
In 15 female rhesus macaques ranging from gestational day 140 to 32.4 years, researchers mapped microglia, the brain’s resident immune cells, in a brain region called the hippocampus. The cross-sectional observational study used archived tissue, automated cell detection and spatial analysis.
Density fell during early postnatal life before increasing through adulthood and aging. The dentate gyrus, one part of the hippocampus, showed the greatest age-related change. Cells were most widely spaced in the group aged 2.5–6 months. Aged animals, aged 18.7–32.4 years, also had more local clustering in CA1, another hippocampal region, than the postnatal and combined juvenile/adult groups.
Why it matters
The hippocampus undergoes structural changes with age. The authors’ approach offers a framework for studying immune-cell organization within the aging primate brain.
Caveats
The study compared tissue from different animals rather than tracking changes within individuals. It included only 15 females, so the findings do not show whether the same patterns occur in males or humans.
The paper
George Mason University
Scientific Reports, Jun 30, 2026, Open access
