Three-dimensional and stereological characterization of the human substantia nigra during aging.
Level 4 - case-series / case-control
Post-mortem cross-sectional stereological study of human brain tissue without a comparative control group.
PubMed 26386691 · doi:10.1007/s00429-015-1108-6
What was done
Post-mortem brainstems or complete brains from 15 cognitively normal donors aged 50 to 91 years without parkinsonian signs were analyzed. Tissue was formalin-fixed, celloidin-mounted, serially sectioned, and Nissl-stained. High-resolution computer-assisted 3D reconstructions and stereological evaluations were conducted to map substantia nigra (SN) volume and morphology.
What was found
SN volume correlated negatively with age (rho = -0.53, p = 0.04). High variability in neuronal numbers and density was observed across participants. 3D reconstructions demonstrated that the human SN forms an interconnected neuronal reticulum rather than isolated neuronal islands.
Why it matters
This study provides normative structural data for high-resolution neuroimaging, suggesting that SN volume alone is an unreliable diagnostic surrogate for individual disease status without multimodal imaging.
Limits
The sample size is very small (n = 15) and confined to older adults aged 50 to 91. The cross-sectional post-mortem design cannot measure individual longitudinal changes, and specific numerical values for neuron counts and density were not reported in the abstract.