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Updated: May 10, 2026
Immunohistochemistry and Multiple Labeling with Antibodies from the Same Host Species to Study Adult Hippocampal Neurogenesis
Published on: April 22, 2015
Characterization of a population of neural progenitor cells in the infant hippocampus
Simon M L Paine1, Alex R Willsher, Sarah L Nicholson
1Neural Development Unit, Birth Defects Research Centre, UCL Institute of Child Health, London, UK; Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.
Insights
Infant hippocampus rod cells are not microglia but neural progenitors, advancing understanding of brain development and disease diagnosis. This finding is crucial for distinguishing normal cells from reactive microglia.
Area of Science:
- Neuroscience
- Developmental Biology
- Pathology
Background:
- Abnormalities in the infant hippocampus are linked to epilepsy and sudden death.
- A unique rod cell population in the infant dentate gyrus was previously misidentified as microglia.
- The hippocampus is a key site for postnatal neurogenesis.
Purpose of the Study:
- To investigate the immunophenotype of infant hippocampal rod cells.
- To determine if these cells are microglia or neural progenitors.
- To clarify the role of these cells in infant brain development and disease.
Main Methods:
- Analysis of archived post-mortem infant hippocampal tissue (n=40).
- Application of a comprehensive antibody panel for immunophenotyping.
- Utilized markers for microglia and neural progenitors.
Main Results:
- Rod cells were negative for microglial markers (CD45, CD68, HLA-DR).
- Cells expressed neural progenitor markers (doublecortin, nestin) and a neural marker (TUJ1).
Conclusions:
- Infant hippocampal rod cells are confirmed as neural progenitors, not microglia.
- Findings enhance understanding of human postnatal neurogenesis.
- Distinguishes normal neural progenitors from reactive microglia in diagnostics.
Aims:
Abnormalities of the hippocampus are associated with a range of diseases in children, including epilepsy and sudden death. A population of rod cells in part of the hippocampus, the polymorphic layer of the dentate gyrus, has long been recognized in infants. Previous work suggested that these cells were microglia and that their presence was associated with chronic illness and sudden infant death syndrome. Prompted by the observations that a sensitive immunohistochemical marker of microglia used in diagnostic practice does not typically stain these cells and that the hippocampus is a site of postnatal neurogenesis, we hypothesized that this transient population of cells were not microglia but neural progenitors.
Methods:
Using archived post mortem tissue, we applied a broad panel of antibodies to establish the immunophenotype of these cells in 40 infants dying suddenly of causes that were either explained or remained unexplained, following post mortem investigation.
Results:
The rod cells were consistently negative for the microglial markers CD45, CD68 and HLA-DR. The cells were positive, in varying proportions, for the neural progenitor marker, doublecortin, the neural stem cell marker, nestin and the neural marker, TUJ1.
Conclusions:
These data support our hypothesis that the rod cells of the polymorphic layer of the dentate gyrus in the infant hippocampus are not microglia but a population of neural progenitors. These findings advance our understanding of postnatal neurogenesis in the human hippocampus in health and disease and are of diagnostic importance, allowing reactive microglia to be distinguished from the normal population of neural progenitors.
