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Table 1 Summary of histochemical and microscopy tests on pollen and seed cone bracts

From: Heterochrony and repurposing in the evolution of gymnosperm seed dispersal units

Histochemical test Pollen cone bract Seed cone bract
Epidermis Fibers Parenchyma Epidermis (Stage 1–3) Fibers (Stage 1–3) Parenchyma
Primary wall Secondary wall Primary wall Secondary wall (Stage 1–2) (Stage 3)
Toluidine blue O Green Blue Not stained Blue Green Blue Not stained Blue Blue
PAS −−− +++ −−− +++ −−− +++ −−− +++ −−−
Alcian blue −−− −−− −−− +++ −−− −−− −−− +++ −−−
Ruthenium Red −−− +++ −−− −−− −−− +++ −−− −−− −−−
IKI (Lugol) −−− −−− −−− −−− −−− −−− −−− −−− −−−
Polarized light −−− +++ +++ −−− −−− +++ +++ −−− −−−
Coomassie blue R-2503 −−− ++− −−− +++* −−− ++− −−− +++* −−−
Sudan Black B −−− −−− −−− −−− −−− −−− −−− −−− −−−
  1. Cytochemical test specificity: toluidine blue O—polyanionic acid groups: blue, phenolic compounds: green, pectins: purple [46]; PAS—insoluble polysaccharides [44]; Alcian blue—mucilage [42, 45]; ruthenium red—pectins and IKI (Lugol)—starch [47]; polarized light—birefringent crystalline fibers [48]; Sudan Black B—lipids (including phospholipids) [49]. (+++) strong, (++−) positive, (+−) weak, (−−) none observed, (*) peripheral to vacuole