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External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. [1] It is contrasted with internal fertilization , in which sperm are introduced via insemination and then combine with an egg inside the body of a female organism.
His revised modes are ovuliparity, with external fertilisation; oviparity, with internal fertilisation of large eggs containing a substantial nutritive yolk; ovo-viviparity, that is oviparity where the zygotes are retained for a time in a parent's body, but without any sort of feeding by the parent; histotrophic viviparity, where the zygotes ...
(True) oviparity, in which fertilization is internal, is taken to be the derived condition, whether the male injects the sperm into the female intromittently or whether she actively or passively picks it up — the female lays eggs containing zygotes with a substantial quantity of yolk to feed the embryo while it remains in the egg, and in many ...
Aquatic arthropods may breed by external fertilization, as for example horseshoe crabs do, [33] or by internal fertilization, where the ova remain in the female's body and the sperm must somehow be inserted. All known terrestrial arthropods use internal fertilization.
Allogamy is the fertilization of flowers through cross-pollination, this occurs when a flower's ovum is fertilized by spermatozoa from the pollen of a different plant's flower. [ 15 ] [ 16 ] Pollen may be transferred through pollen vectors or abiotic carriers such as wind.
The number of childfree women is at a record high: 48 percent of women between the ages of 18 and 44 don’t have kids, according to 2014 Census numbers. The Huffington Post and YouGov asked 124 women why they choose to be childfree.
Cowlick vs. Balding: Key Differences. A cowlick differs from a bald spot in a couple key ways.. First, a cowlick is a natural, normal feature of your scalp that occurs as a result of your genes.
Fertilization is the fusion of gametes to produce a new organism. In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization.