The histological staining was carried out to establish the ontogeny of explants containing shoot buds. Explants at different stages of their development (3, 8 and 12 days of regeneration) were fixed in FAA (formalin, acetic acid, absolute alcohol: 10, 5, 85; v/v) for 24 hours. After dehydrating in ethanol (70, 95 and 100%) and xylene, textures were fixed in paraffin, sectioned with a microtome at 30 µm and then stained with metylen blue. The sections were prepared in a lam for observation under a light microscope.