 Pollination, pollination is the transfer of pollen from a male part of a plant to a female part of a plant, enabling later afterlization and the production of seeds, most often by an animal or by wind. Pollinating agents are animals such as insects, birds, and bats, water, wind, and even plants themselves. When self-pollination occurs within a closed flower, pollination often occurs within a species. When pollination occurs between species it can produce hybrid offspring in nature and in plant breeding work. In angiosperms, after the pollen grain has landed on the stigma, it develops a pollen tube which grows down the style until it reaches an ovary. Sperm cells from the pollen grain then move along the pollen tube, enter an ovum cell through the micro pile and fertilize it, resulting in the production of a seed. A successful angiosperm pollen grain gametified containing the male gametes is transported to the stigma, where it germinates and its pollen tube grows down the style to the ovary. It's to gametes travel down the tube to where the gametified S containing the female gametes are held within the carpal. One nucleus fuses with the polar bodies to produce the endosperm tissues, and the other with the ovule to produce the embryo hence the term double fertilization. In gemnisperms, the ovule is not contained in a carpal, but exposed on the surface of a dedicated support organ, such as the scale of a cone, so that the penetration of carpal tissue is unnecessary. Details of the process vary according to the division of gemnisperms in question. To main modes of fertilization are found in gemnisperms. Psycads and ginko have modal sperm that swim directly to the egg inside the ovule, whereas conifers and natophytes have sperm that are unable to swim but are conveyed to the egg along the pollen tube. The study of pollination brings together many disciplines, such as body, horticulture, entomology, and ecology. The pollination process as an interaction between flower and pollen vector was first addressed in the 18th century by Christian Conrad Sprengel. It is important in horticulture and agriculture, because fruiting is dependent on fertilization, the result of pollination. The study of pollination by insects is known as antichology.