The stereocilia of the epididymis are structures which aid in absorption. They are long cytoplasmic projections but have no motility.
Unlike the stereocilia of the ear, those in the epididymis are more like long microvilli that cover the open surface of the epididymis. These extensions increase the surface area of the cell allowing for greater absorption and secretion.
The stereocilia have no internal microtubule structure and unlike true cilia, are non-motile. The internal actin network increases the surface area just like microvilli. Because sperm are initially nonmotile as they leave the seminiferous tubules, large volumes of fluid are secreted to propulse the spermatozoa, along with the cilia of the pathway to the epididymus. The core function of the stereocilia is to resorb this large volume of fluid (90% of fluid volume), as the spermatozoa start to become motile here. They do not reach full motility (hypermotility) until they reach the vagina where the alkaline pH is neutralized by acidic vaginal fluids.
- ^ How sperm are re-absorbed into the body. http://www.vasectomy-information.com/moreinfo/reabsorb.htm (accessed 2/16/06)
- ^ Efferent Ducts and Epididymis. http://www3.umdnj.edu/histsweb/lab16/lab16efferentandepididmys.html (accessed 2/16/06).
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