Fertilisation
Fertilisation (
BE), also spelled
fertilization (
AE), which is less ambiguously referred to as
syngamy, is the process of a
sperm fusing with an
ovum, which eventually leads to the development of an
embryo.
The whole process of development of new individuals is called
procreation.
Fertilisation in mammals
To deliver the sperm to female, the male inserts his external sexual organ into the opening to vagina, the passage into the female's sexual organ. (This process is a part of copulation.) Once the male ejaculates, a large number of sperm cells travel toward the ovum. For fertilisation to occur, a single sperm cell must successfully penetrate the ovum's coat. Once this happens, the female is said to be pregnant.
Fertilisation in plants
After the female part of the flower is pollinated, pollen grains attempt to travel into the ovary by creating a path called "pollen tube." The pollen tube does not directly reach the ovary in a straight line. It travels near the skin of the style and curls to the bottom of the ovary, then near the receptacle, it breaks through the ovule and reaches the ovum to fertilize it. After being fertilized, the ovary starts to swell and becomes a fruit.
With multi-seeded fruits, multiple grains of pollen are necessary for syngamy with each ovule. \nThe process is easy to visualize if one looks at corn silk, which is the female flower of corn. Pollen from the tassel (the male flower) falls on the sticky external portion of the silk, then pollen tubes grow down the silk to the attached ovule. The dried silk remains inside the husk of the ear as the seeds mature, so one can carefully remove the husk to show the floral structures. The development of the flesh of the fruit is proportional to the percentage of fertilized ovules. For example, with watermelon, about a thousand grains of pollen must be delivered and spread evenly on the three lobes of the stigma to make a normal sized and shaped fruit.
See also
\n* in vitro fertilisation\n* pregnancy\n* pollination
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