It can be used to sort out sperm that are most healthy, as well as for determination of more specific traits, such as sex selection in which spermatozoa are separated into X- (female) and Y- (male) chromosome bearing populations based on their difference in DNA content.
The resultant 'sex-sorted' spermatozoa are then able to be used in conjunction with other assisted reproductive technologies such as artificial insemination or in-vitro fertilization (IVF) to produce offspring of the desired sex - in farming animals but also in human medical practice.
However, because flow cytometry-based sperm sorting often uses fluorescent dyes that often stain DNA, the safety of this technique in human reproductive medicine is a matter of scientific discussion.
[4][5] However, flow cytometry is the only currently used technique able to determine the sex of future progeny by measuring DNA content of individual sperm cells.
[6] The so-called Beltsfield Sperm Sexing Technology was developed by USDA in conjunction with Lawrence Livermore National Laboratories, relying on the DNA difference between the X- and Y- chromosomes.
[7] Prior to flow cytometric sorting, semen is labeled with a fluorescent dye called Hoechst 33342 which binds to the DNA of each spermatozoon.
The sperm is selected not only by its highest motility but also by other factors such as DNA integrity, production of reactive oxygen species and viability.
This selection is largely circumvented in case of in-vitro fertilization which leads to higher incidence of birth defects associated with assisted reproductive techniques.
[2] For example, annexin V staining followed by MACS can significantly improve pregnancy rates in couples with previous assisted reproduction failure.
Utilizing artificial insemination with sorted sperm is seen as a way to create an optimal ratio of male and female calves to increase dairy milk production.
The procedure was made available to a limited number of participants each month, in addition to fulfilling certain criteria, such as having a disease with sex linkage or having at least one child (for family balancing).
[19] There are currently MicroSort laboratories and collaborating physicians in several countries (some for general purposes, some only offering service in case of genetic disease risks associated with one sex).