Figure 1

1) microprogation of shoots; 2) ánd 3) apex excision; 4) encapsulation of apical shoot-tips in alginate beads; 5) sucrose pretreatment; 6) dehydration over silica gel in airtight boxes; 7) apical shoot-tips in sterile cryotubes; 8) rapid immersion of the cryovials into liquid nitrogen.