Figure 6. Inner surface of the inner fruit pericarp following Toluidine Blue dye staining.

The permeability and integrity of the inner epidermal lipid membrane was tested with a Toluidine Blue O dye penetration test. The lower panels are shown at greater magnification. The test was applied to fruit at four ripening stages: MG, B, T, and R. Although the pericarp and locular tissues were stained, the inner epidermis of the pericarp was not stained in any stage. M, mature green; B, breaker; T, turning; R, red ripe.