Neo-Lamarckism - August Weismann

cut off the tails of mice for many generations and showed that this mutilation had no effect on the tail length of their descendants.

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#Unit 5. Developmental Biology

Toward the end of capacitation, sperm become hyperactivated—The symmetrical beating of the flagellum is changed into a rapid asynchronous beat with a higher degree of bending. 

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#Unit 5. Developmental Biology

Hyperactivation mediated by the opening of the sperm specific calcium channels, the CatSper proteins, in the sperm tail.

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#Unit 5. Developmental Biology

Once a sperm has reached the oocyte-cumulus complex, hyperactivation, along with a hyaluronidase enzyme on the outside of the sperm cell membrane, enables the sperm to digest a path through the extracellular matrix of the cumulus cells

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#Unit 5. Developmental Biology

Thermotaxis  The ability to sense temperature difference and preferentially swim from cooler to warmer sites is found only in capacitated sperm

 

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#Unit 5. Developmental Biology

Capacitated mammalian sperm can sense thermal differences as small as 0.014 degrees Celsius over a millimeter and tend to migrate toward the higher temperature

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#Unit 5. Developmental Biology

The capacitated sperm are also able to detect and respond to picomolar amounts of the hormone progesterone, which is secreted by the cumulus cells surrounding the egg