Histological assessment of cerebellar granule cell layer in postmortem brain; a useful marker of tissue integrity?

Tissue quality control measures are routinely performed in brain banks with the assessment of brain pH being the most common measure. In some brain banks the assessment of the RNA integrity number is also performed, although this requires access to specialised equipment and is more expensive. The aim of this study is to determine if there is a correlation between the visual assessment of cerebellar granule cell integrity and brain pH or RIN. One hundred and five consecutive cases from the NSW Tissue Resource Centre, Sydney, Australia were accessed. The cerebrum was hemisected and one hemisphere sliced parasagittally at approximately 1-2 cm intervals and frozen. The other hemisphere was fixed in 15% buffered formalin for 2-3 weeks. The contralateral cerebellar hemisphere was preserved in the same manner as the cerebral hemisphere. Samples of fixed tissue were embedded in paraffin, 7 μm sections cut and stained routinely with hematoxylin and eosin. The granular cell layer (GCL) was assessed microscopically to determine the degree of autolytic degradation. Degradation was graded as nil, mild, moderate or severe. Brain tissue pH and RIN were measured using standardised protocols. This study showed that both brain pH and RIN significantly correlated with the severity of the degradation of the cerebellar granule cell layer. This additional screening tool can be performed during routine histological review of the cerebellar tissue to assess the suitability for further investigation of tissue quality.