In general, the SEM observations indicated two distinct
extraction mechanisms for conventional and ultrasound
procedures, the first involving diffusion of the plant extract
components across the unbroken gland wall, due to
the rising temperature effect in the medium, and the
second involving exudation of oil from broken and damaged
cell walls and even cells, due to a strong ultrasonic
mechanical effect, which should in general result in instantaneous
release of the plant extract components into
the surrounding solvent.