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Cryptic female choice is a form of mate choice which occurs both in pre- and post-copulatory circumstances in which females of certain species use physical or chemical mechanisms to control a male's success of fertilizing their ova or ovum; i.e. by selecting whether sperm are successful in fertilizing their eggs or not.
Multiple studies have shown that the physical contact between the sperm and the egg can cause a chemical reaction in the female. [2] This reaction occurs when the egg comes in contact with non-compatible surface glycans and can impact the sperm's potential for fertilization by causing structural changes in the sperm's surface glycans. [2]
The sperm plasma then fuses with the egg's plasma membrane and their nuclei fuse, triggering the sperm head to disconnect from its flagellum as the egg travels down the fallopian tube to reach the uterus. In vitro fertilization (IVF) is a process by which egg cells are fertilized by sperm outside the womb, in vitro.
A sperm which contains an X chromosome, produced in the usual way in the testicles, referring to the occurrence of such a sperm fertilizing an egg and giving birth to a female. [1] A sperm which artificially contains genetic material from a female. [2] Since the late 1980s, scientists have explored how to produce sperm where all of the ...
In cichlid fish, it has been found that increased sperm competition can lead to evolved larger sperm numbers, sperm cell sizes, and sperm swimming speeds. [ 49 ] In some insects and spiders, for instance Nephila fenestrate , the male copulatory organ breaks off or tears off at the end of copulation and remains within the female to serve as a ...
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"This can make a woman feel like they are alone and that everyone else is getting pregnant before them, when in reality most couples don’t get pregnant when they first try to conceive and that ...
The law also caps the number of families that can use a single donor and requires sperm and egg agencies to make a “good faith effort” keep permanent, up-to-date medical records on donors.