Pollen form two sperm cells. The sperm cells are carried to their destination in the tip of the pollen tube. Double-strand breaks in DNA that arise during pollen tube growth appear to be efficiently repaired in the generative cell that carries the male genomic information to be passed on to the next plant generation. However, the vegetative cell that is responsible for tube elongation appears to lack this DNA repair capability. Pollen's sporopollenin outer sheath affords it some resistance to the rigours of the fossilisation process that destroy weaker objects; it is also produced in huge quantities. There is an extensive
Compartmentalization of decay in trees compartmentalization. According to CODIT, when a tree is wounded cells undergo changes to form "walls" around the wound, slowing or preventing the spread of disease and decay to the rest of the tree. By increasing understanding of how trees respond to decay, CODIT has had many applications. For example, arborists are frequently called upon to analyze the danger posed to people or property by a damaged or decaying tree. By knowing how decay is likely to spread, such hazard tree analyses may be more accurate, thereby preventing unnecessary tree removal, property damage, or injury. For another example, in the production