From Wikipedia, the free encyclopedia Sperm sorting
Sperm sorting
Sperm sorting is a means of choosing what type of sperm DNA of each spermatozoon. As the X chromosome is larg-
cell is to fertilize the egg cell. It can be used to sort out er (ie has more DNA) than the Y chromosome, the "fe-
sperm that are most healthy, as well as determination male" (X-chromosome bearing) spermatozoa will absorb
of more specific traits, such as sex selection in which a greater amount of dye than its male (Y-chromosome
spermatozoa are separated into X- (female) and Y- (male) bearing) counterpart. As a consequence, when exposed
chromosome bearing populations based on their differ- to UV light during flow cytometry, X spermatozoa fluo-
ence in DNA content. The resultant ’sex-sorted’ sperma- resce brighter than Y- spermatozoa. As the spermatozoa
tozoa are then able to be used in conjunction with other pass through the flow cytometer in single file, each sper-
assisted reproductive technologies such as artificial in- matozoon is encased by a single droplet of fluid and as-
semination or in-vitro fertilization (IVF) to produce off- signed an electric charge corresponding to its chromo-
spring of the desired sex. some status (eg X-positive charge, Y-negative charge).
The stream of X- and Y- droplets is then separated by
For general health means of electrostatic deflection and collected into sepa-
rate collection tubes for subsequent processing [7].
DNA damage in sperm cells may be detected by using Ra-
man spectroscopy. [1] It is not specific enough to detect Accuracy
individual traits, however.[1] While highly accurate, sperm sorting by flow cytometry
The sperm cells having least DNA damage may subse- will not produce two completely separate populations.
quently be injected into the egg cell by intracytoplasmic That is to say, there will always be some "male" sperm
sperm injection (ICSI).[1] among the "female" sperm and vice versa. The exact per-
centage purity of each population is dependent on the
For sex selection species being sorted and the ’gates’ which the operator
places around the total population visible to the ma-
Methods chine. In general, the larger the DNA difference between
the X and Y chromosome of a species the easier it is to
Sperm sorting utilizes the technique of flow cytometry
produce a highly pure population. In sheep and cattle,
to analyze and ’sort’ spermatozoa. During the early to
purities for each sex will usually remain above 90% de-
mid 1980s, Dr. Glenn Spaulding was the first to sort viable
pending on ’gating’, while for humans these may be re-
whole human and animal spermatozoa using a flow cy-
duced to 90% and 70% for "female" and "male" spermato-
tometer, and utilized the sorted motile rabbit sperm for
zoa, respectively.[8]
artificial insemination. Subsequently, the first patent ap-
plication disclosing the method to sort "two viable sub-
Ethical concerns
populations enriched for x- or y- sperm" [2] was filed in
April of 1987 as US Application Serial Number 35,986 and Further information: Sex selection#Ethical concerns
later became part of US Patent 5,021,244; and the patent For the most part, sperm sorting shares the ethical con-
included the discovery of haploid expression (sex-associ- cerns implicit to the idea of sex selection. However, the
ated membrane proteins, or SAM proteins) and the devel- fact that sperm sorting is in effect sex-preselection, with
opment of monoclonal antibodies to those proteins. Ad- the sex of the offspring decided at conception rather
ditional applications and methods were added, including than post-conception (preimplantation genetic diagno-
antibodies, from 1987 through 1997 [3]. At the time of the sis), post-implantation (ultrasound) or post-birth, makes
patent filing, both Lawrence Livermore National Labora- the technique decidedly more attractive from an ethical
tories and the USDA were only sorting fixed sperm nu- standpoint.
clei [4], after the Application Serial Number 35,986 patent
filing a new technique was utilized by the USDA where Regulation
"sperm were briefly sonicated to remove tails"[5]. USDA In the US, for humans, the practice of sperm sorting is
in conjunction with Lawrence Livermore National Labo- tightly regulated by the FDA. In effect, it remains an on-
ratories, ’Beltsfield Sperm Sexing Technology’ relies on going clinical trial, with the procedure made available to
the DNA difference between the X- and Y- chromosomes a limited number of participants each month, in addition
[6]. Prior to flow cytometric sorting, semen is labeled with to fulfilling certain criteria, such as having a disease with
a fluorescent dye called Hoechst 33342 which binds to the
1
From Wikipedia, the free encyclopedia Sperm sorting
sex linkage or having at least one child (for family bal- spermatozoa into two populations. Gamete
ancing).[8] Research Volume 16, Issue1, pages 1-9, January
1987; http://onlinelibrary.wiley.com/doi/10.1002/
See also mrd.1120160102/abstract
[5] L. A. Johnson, J. P. Flook and M. V. Look, Flow
• Sex selection cytometry of X and Y chromosome-bearing sperm
for DNA using an improved preparation method
References and staining with Hoechst 33342. Gamete Research
Volume 17, Issue 3, July 1987, Pages: 203–212;
[1] ^ Ranking sperm cells could improve the odds of in http://onlinelibrary.wiley.com/doi/10.1002/
vitro fertilization. By Courtney Humphries. mrd.1120170303/abstract
TechnologyReview. Wednesday, January 21, 2009 [6] Garner DL, Seidel GE. History of commercializing
[2] US Patent 5,021,244, column 9, Sorting Sperm; sexed semen for cattle. Theriogenology 2008;69:
http://patft.uspto.gov/netacgi/nph- 886-895.
Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5021244.PN.&O
[7] Seidel GE, Jr., Garner DL. Current status of sexing
5021244&RS=PN/5021244 mammalian spermatozoa. Reproduction 2002;124:
[3] US Patent 5,021,244; 5,346,990; 5,369,012; 5,439,362; 733-743.
5,496,722; 5,648,468; 5,660,997; PCT/US1989/002069 [8] ^ Genetics & IVF Institute: MicroSort Clinical Trial
[4] L. A. Johnson, J. P. Flook, M. V. Look, D. Pinkel, Flow
sorting of X and Y chromosome-bearing
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