**2.1.7.3 Transmission electron microscopy**

A standard glutaraldehyde-osmium fixation method was used, followed by dehydration through an acetone series embedding in a low viscosity epoxy resin (Spurr, 1969). Sections of the meristematic regions of axillary buds and shoot tips were collected on 200 mesh hexagonal copper 3.05 mm grids. Sections were post-stained with uranyl acetate and lead citrate, washed with distilled water, and viewed and photographed with a JEOL 100-S transmission electron microscope.
