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− | <big><center>[[Reproductive System|'''BACK TO REPRODUCTIVE SYSTEM''']]</center></big>
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− | <big><center>[[Reproductive_System#Reproductive_Technologies|'''BACK TO REPRODUCTIVE TECHNOLOGIES''']]</center></big>
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| == Principle == | | == Principle == |
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| * This allows the sperm to be sorted by '''flow cytometry'''. | | * This allows the sperm to be sorted by '''flow cytometry'''. |
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| + | == Flow Cytometry == |
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− | == Flow Cytometry ==
| + | [[Image:Semen Sorting.jpg|thumb|right|150px|<p>Schematic Diagram to show Semen Sexing by Flow Cytometry</p><sup> ©Nottingham University 2008</sup>]] |
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| + | * Ejaculated spermatozoa are treated with a DNA dye (fluorochrome). |
| + | * X-bearing sperm absorb more dye than Y-bearing sperm. |
| + | * X-bearing sperm thus emit more intense light when excited by a laser. |
| + | * Sperm are also treated with a dye that greatly suppresses the signal from dead sperm. |
| + | ** Dead sperm are therefore identified and rejected. |
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| + | * Once spermatozoa enter the flow cytometer chamber, they pass single-file through a small nozzle. |
| + | * At a region just outside the nozzle, an excitation laser beam activates the fluorescent dye in each sperm. |
| + | * Each live sperm produces an emission with an intensity that is directly related to the quantity of DNA within the sperm head. |
| + | ** X-bearing live sperm produce more intensity. |
| + | * A light sensing device is coupled to a computer that determines the intensity of light emission by each sperm and the order of passage of each sperm through a column below the nozzle. |
| + | * When the sperm pass through charged plates, they are assigned either a positive or negative charge depending on their DNA content (X or Y chromosome). |
| + | * When the microdroplet containing a single sperm passes through an electromagnetic field the computer applies an appropriate charge and directs the droplet (and sperm) to one side or the other. |
| + | * Dead sperm are discarded into the centre tube. |
| + | * At the end there are three vessels that contain sperm: |
| + | ** One contains a high proportion of X-bearing sperm. |
| + | ** One contains a high proportion of Y-bearing sperm. |
| + | ** One contains dead sperm |
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| + | [[Category:Reproductive Technologies]] |
| + | [[Category:Bullet Points]] |