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
Water-based pipe coating Water-based pipe coating A water-based pipe coating is an environmentally friendly coating that is applied to the inner and outer surfaces of ductile iron pipe. The coating serves to protect the water supply lines from corrosion whether from the outside or the inside. It also serves to protect the drinking water from contamination. The coating is an emulsion manufactured using asphaltene and water primarily, with other raw materials according to the manufacturer’s specifications. Water-based coatings began development in the late 1980s. In the early 1990s they began to be widely used, specifically marketed towards drinking water supply lines. Previously, water