Table 2. Histochemical markers of neuronal maturation.

		Post-mortem	Quality
Product	Onset*	Reliability**	After 10 years
Luxol fast blue	late	5 days	preserved
Periodic acid-Schiff (PAS) reaction*****	late	12 – 24 hours	preserved
Acridine orange (AO) fluorochrome	intermediate/late	5 days	fades 5 minutes
Mitochondrial oxidative enzymes****	late	30 minutes	preserved
Bielschowsky or Bodian silver impregnation	late	5 days	preserved

*Late onset is defined as expression only after the neurone initiates transmitter synthesis and forms synapses. Intermediate onset is defined by expression in neuroblasts during migration, before transmitter synthesis and synaptogenesis, but not as progenitor cells. Early onset is defined by expression as progenitor neuroepithelial cells with early neuronal lineage, before migration initiated. **Post-mortem reliability indicates the period between fetal death and fixation of tissue. Some stillborn fetuses may have died 1 – 3 days before delivery and autolysis in those cases would have proceeded rapidly because the tissues were at the mother’s body temperature. Quality after 10 years refers to the preservation of reactivity in archived microscope slides prepared 10 years earlier. ***Tau and vimentin are the only proteins in this list that is expressed early and then disappear from immunocytochemical demonstration in intermediate stages of neuronal differentiation. ****Frozen, unfixed sections required; more suitable for surgical than autopsy tissue. *****Glycogen digestion within cells, including neurones, continues post-mortem.