Pollen grains contain the male gametes required for sexual reproduction of a plant/ flower. These are haploid, and only contain half the full set of chromosomes; the other half is contributed by the female gamete (or ovule).
A grain of pollen contains:
The pollen grain "germinates" on the stigma of the receptive flower and grows down the style, once it reaches the ovule the germ cell/ nucleus fuses with the nucleus of the ovule and an embryo is formed
After pollination, each pollen grain grows a pollen tube that extends down into the style of the flower and reaches the ovary. The pollen tube delivers the male gametes (sperm cells) to the ovule for fertilization to occur.
A single pollen grain contains the generative material that forms the male gametes. It also contains the material that will form the pollen tube when the pollen lands on the pistil. These are covered by a thin layer called the intine or endospore as well as a thick protective wall called the exine or exospore.
Ovules contain the female reproductive cells of a plant, also known as the egg cells. These are the cells that, when fertilized by pollen, develop into the seeds of the plant. Each ovule is enclosed within the ovary of a flower.
A ripened ovule that contains the embryo becomes the seed.
The female structure of the flower is the gynoecium that is made up of the ovary, style and stigma. The ovary produces the ovule. The male structure is the androecium. It is made up of the filament and anther. The filaments bear the anthers. The anthers produce pollen.
After pollination, each pollen grain grows a pollen tube that extends down into the style of the flower and reaches the ovary. The pollen tube delivers the male gametes (sperm cells) to the ovule for fertilization to occur.
When they land on the style they begin to bore their way through the stigma all the way to the ovule. Through the tube made by the tube nucleus of the pollen grain: each pollen grain has two nuclei, one called generative nucleus which combines with the nuclei of the ovule, and the other called tube nucleus tube nucleus which forms a tube that penetrates the stigma till it reaches ovule then it degenerates.
When they land on the style they begin to bore their way through the stigma all the way to the ovule. Through the tube made by the tube nucleus of the pollen grain: each pollen grain has two nuclei, one called generative nucleus which combines with the nuclei of the ovule, and the other called tube nucleus tube nucleus which forms a tube that penetrates the stigma till it reaches ovule then it degenerates.
When a pollen grain lands on stigma, pollination occurs. The pollen grain germinates and the pollen tube grows through the style. The sperm nucleus travels through the tube (generated by the tube nucleus) and fuses with an ovule which then develops into an embryo (or zygote)
You are describing pollen grains. Each grain contains a male gamete that can fertilize the female ovule, to which pollen is transported by the wind, insects, or other animals.
One.
The structure grown by a pollen grain that contains two sperm nuclei is called the pollen tube. The pollen tube is responsible for delivering the sperm nuclei to the ovule for fertilization in plants.
The pollen tube of most seed plants acts as a conduit to transport sperm cells from the pollen grain, either from the stigma (in flowering plants or angiosperms) to the ovules at the base of the pistil, or directly through ovule tissue in some gymnosperms (conifers and gnetophytes).
No, sperm cells do not grow out of a pollen grain. In plants, sperm cells are produced within the pollen grain, and they are involved in fertilization when the pollen grain reaches a female reproductive structure. Each pollen grain contains two sperm cells.
A single pollen grain contains the generative material that forms the male gametes. It also contains the material that will form the pollen tube when the pollen lands on the pistil. These are covered by a thin layer called the intine or endospore as well as a thick protective wall called the exine or exospore.
When pollen falls on a flower's pistil, a process called pollination occurs. The pollen travels down the pistil to reach the ovary, where fertilization takes place. This fertilization leads to the formation of seeds, which eventually develop into fruits.
Flower fertilization is when the pollen gets into the female parts of the flower and the seeds start to form. Each ovule or egg needs some pollen to form a seed.