Superfetation (also spelled superfoetation and superfoetation - see fetus) is the simultaneous occurrence of more than one stage of developing offspring in the same animal. It is not believed that it occurs naturally in humans.
In mammals, it manifests as the formation of an embryo from a different estrous cycle while another embryo or fetus is already present in the uterus. When two separate instances of fertilisation occur during the same menstrual cycle, it is known as superfecundation.
Superfetation is claimed to be common in some species of animals. In mammals, it can occur only where there are two uteri, or where the estrous cycle continues through pregnancy.
Video Superfetation
Other animals
Animals that have been claimed to be subject to superfetation include rodents (mice and rats), rabbits, horse, sheep, marsupials (kangaroos and sugar gliders), felines, and primates (humans). Superfetation has also been clearly demonstrated and is normal for some species of poeciliid fishes.
Maps Superfetation
Humans
While proposed cases of superfetation have been reported in humans, the existence of this phenomena in humans is deemed unlikely. Better explanations include differential growth between twins due to various reasons such as twin-to-twin transfusion syndrome. Artificially induced superfetation has been demonstrated, although only up to a short period after insemination.
References
External links
- Superfetation in Beef Cattle Doctoral Thesis; Joel Andrew Carter, Louisiana State University, Defended 2002-03-18
- Superfetation in fish
Source of the article : Wikipedia
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