2.4.3. Microscopy (light, scanning and transmission electron microscopy)
2.4.3.1. Light and transmission electron microscopy. Avocado tissue was
cut into 10-mm diameter discs approximately 2 mm thick. Discs were
transferred into fix ative (2% freshly prepared formaldehyde, 2.5% glutar-
aldehyde in 0.1 M phosphate buffer pH 7.2) and stored at 4 °C before processing and observation. For light microscopy blocks of tissue around
3×4×2mmwereexcisedfromthedisc,washedthreetimesin0.1M
phosphate buffer (pH 7.2) and then sectioned at 200 or 300 μmusinga
stainless steel blade attached to a Vibratome 1000 (Technical Products
International, St Louis, MO, USA). Sections were either stained using a
0.1% aqueous solution of toluidine blue and observed using bright field
microscopy or were viewed without staining by differential interference
contrast microscopy using an Olympus Vanox AHT3 (Olympus Optical
Co. Ltd., Tokyo, Japan).