Pollen tube subsequent pollination (transfer of pollen grains to the pistil, the female reproductive organ). Transfer of pollen is usually carried out by wind, water, or animals . The ovaries hold the ovules that produce the female gamete: the egg cell, which waits in place for fertilization. Once a pollen grain settles on a compatible pistil, it may germinate in response to a sugary fluid secreted by the mature stigma. Lipids at the surface of the stigma may also stimulate pollen tube growth for compatible pollen. Plants that are self-sterile often inhibit the pollen grains from their own flowers from growing pollen
Coating substrate, such as paper, fabric, film, foil, or sheet stock. If the substrate starts and ends the process wound up in a roll, the process may be termed "roll-to-roll" or "web-based" coating. A roll of substrate, when wound through the coating machine, is typically called a web. Coatings may be applied as liquids, gases or solids. Coating processes may be classified as follows: Common roll-to-roll coating processes include: Coating A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or