Bearing Spermatozoa Research Articles

Constraints Affecting Fertility of Sex Sorted Semen: An Overview

In most mammals, the male to female sex ratio of offspring is about 50% because half of the sperm contains either the Y chromosome or the X chromosome. Desired sex either male or female which is produced from semen having X or Y bearing sperm is known as sexed semen. Flow cytometry is the only proven method for semen sexing to be commercially viable with more than 90% accuracy to produce calves of desirable sex. The sexed semen technology has several advantages, the production of more female calves and more milk, and lowered risk of dystocia. Increased efficiency of progeny testing, embryo transfer and in-vitro fertilization program has proposed a demand of feasible technology for sex sorting of spermatozoa. In India, this revolutionary technology is in its budding stage. This paper aimed to review the constraints affecting the fertility of sex sorted semen.

MP44-14 SORTING OF SPERM WITH CHROMASELECT DOES NOT SKEW THE RATIO OF X TO Y CHROMOSOME BEARING SPERM

You have accessJournal of UrologyInfertility: Therapy I (MP44)1 Apr 2020MP44-14 SORTING OF SPERM WITH CHROMASELECT DOES NOT SKEW THE RATIO OF X TO Y CHROMOSOME BEARING SPERM Darius Paduch*, Anna Mielnik, and Russ Hayden Darius Paduch*Darius Paduch* More articles by this author , Anna MielnikAnna Mielnik More articles by this author , and Russ HaydenRuss Hayden More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000899.014AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: ChromaSelect is a highly sensitive and specific method of identification and isolation of intact and live human sperm from ejaculate, epididymal or testis specimens with a low concentration (up to 100 sperm /ml). As Y ch is much smaller than X, it is theoretically possible that Y or X bearing sperm will show different fluorescence intensity and thus could result in a skewed selection of one of the sexes in sorted sperm.The aim of our study was to evaluate the ratio of Chr X and Y bearing sperm in intact, live sperm and dead/apoptotic sperm fraction after ChromaSelect identification and sorting. METHODS: Ejaculated human sperm were resuspended to a concentration of 10x106/ml in MHM-C medium, stained using ChromaSelect protocol, and then sorted on SONY-FX500 fluorescent activated cell sorting (FACS). Three groups of samples were prepared: CONTROL – unsorted but stained sperm, LIVE- after sorting intact sperm, and DEAD: after sorting apoptotic and dead sperm based on specific gates. Sperm from each group were placed on microscope slides and number of sperm bearing X, Y, and Chr 8 was counted in at least 500 sperm from each group using FISH with Vysis CEP X (DXZ1) Spectrum Green, CEP Y (DYZ3) Spectrum Orange, and Vysis CEP 8 (D8Z2) Spectrum Aqua DNA. Sperm specific decondensation protocol for FISH was developed by us. The automatic FISH protocol for peripheral WBCs was not adequate for the hybridization of DNA probes in sperm. Only sperm with one signal from Chr 8 were used in the analysis. Four channels epifluorescent microscope was used to acquire images that were then processed using the Bioimaging station. Z-stage deconvolution was used to assure a single signal from each probe was counted. DAPI was used for counterstaining. Experiments were performed in triplicates. JIM 14 was used for statistical analysis. RESULTS: The rate of aneuploidy in any of the specimens was less than 0.5% and was negligible. Single signal for Chr 8 and either X or Y was observed in each counted sperm. The mean ratio of X:Y sperm for CONTROL was 0.99 (49.7% of X positive sperm), for LIVE was 0.99 (49.72 % of sperm had Chr X) and for DEAD was 1.03 (50.68% sperm had Chr X). The total number of sperm counted was 829 in CONTROL, 720 in LIVE, and 916 in DEAD groups. There was no statistically significant difference in the number of X or Y chromosomes bearing sperm between any of the groups. (Chi-square) CONCLUSIONS: Sorting of human sperm using the ChromaSelect method does not skew the ratio of X or Y carrying sperm hence it will not result in any change in the sex ratio in children born using sorted sperm. Source of Funding: NIH grant 1R03HD094046 – 01 to DAP, Irena and Howard Laks and Robert Dow Foundation © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e661-e661 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Darius Paduch* More articles by this author Anna Mielnik More articles by this author Russ Hayden More articles by this author Expand All Advertisement PDF downloadLoading ...

Activation of Toll-like receptor 7/8 encoded by the X chromosome alters sperm motility and provides a novel simple technology for sexing sperm.

In most mammals, the male to female sex ratio of offspring is about 50% because half of the sperm contain either the Y chromosome or X chromosome. In mice, the Y chromosome encodes fewer than 700 genes, whereas the X chromosome encodes over 3,000 genes. Although overall gene expression is lower in sperm than in somatic cells, transcription is activated selectively in round spermatids. By regulating the expression of specific genes, we hypothesized that the X chromosome might exert functional differences in sperm that are usually masked during fertilization. In this study, we found that Toll-like receptors 7/8 (TLR7/8) coding the X chromosome were expressed by approximately 50% of the round spermatids in testis and in approximately 50% of the epididymal sperm. Especially, TLR7 was localized to the tail, and TLR8 was localized to the midpiece. Ligand activation of TLR7/8 selectively suppressed the mobility of the X chromosome–bearing sperm (X-sperm) but not the Y-sperm without altering sperm viability or acrosome formation. The difference in sperm motility allowed for the separation of Y-sperm from X-sperm. Following in vitro fertilization using the ligand-selected high-mobility sperm, 90% of the embryos were XY male. Likewise, 83% of the pups obtained following embryo transfer were XY males. Conversely, the TLR7/8-activated, slow mobility sperm produced embryos and pups that were 81% XX females. Therefore, the functional differences between Y-sperm and X-sperm motility were revealed and related to different gene expression patterns, specifically TLR7/8 on X-sperm.

The Effect of Diffrent Factors on X- and Y Bearing Sperm in Bull Semen

Background: Newborn gender ratio is one of the most important factors in livestock industry. This ratio has affected on economic condition and controls sex-linked genetically transferred diseases. Offspring sex ratio is affected by such various factors. One of these factors is the Y to X bearing sperm ratio in normal semen that is called primary sex ratio, season and individual differences are important factors that can have an effect on primary sex ratio. OBJECTIVES: The objective of this study was to investigate two main effective factors, Individual difference and season, on proportion of sperms containing Y-chromosomes to sperms containing X-chromosomes in bull semen. METHODS: Semens were collected from 16 bulls during summer (Jul-Aug) and winter (Dec. to Jun). After sperm analysis, DNAs were extracted and Real-time PCR performed using three sets of primers to study SRY (Y-chromosome specific sequence), PLP (X-chromosome specific sequence) and PAR (Housekeeping) genes. RESULTS: The results showed that the sex ratio of sperms in normal ejaculation was not equal in different bulls. Moreover, season can affect primary sex ratio. Y-bearing sperm increase in summer. CONCLUSIONS: We concluded that the primary sex ratio is affected by individual differences and season. We also suggested using Northern blotting on PCR products to confirm results.

Comparison between primary sex ratio in spermatozoa of bulls and secondary sex ratio in the deriving offspring

The objectives of the present work were to compare the primary sex ratio in sperm with the secondary sex ratio recorded in the offspring produced by artificial insemination (AI) with the same sperm and assess whether the primary sex ratio is influenced by sperm survival and motility after thawing. Calving data of 98 Holstein Friesian bulls used in AI were collected during 4 years, and commercial semen of the same bulls was analyzed immediately after thawing and after swim-up using a real-time polymerase chain reaction method developed and validated in our laboratory. Calving data relative to single bulls did not reveal any significant deviation between genders from the theoretical 1:1 for none of the bulls, being the mean values of male and female calves born 52.1 ± 2.80% and 47.9 ± 2.71%, respectively. Thereafter, calving events of bulls were classified and analyzed according to four classes of years: 2009 (n = 13,261), 2010 (n = 21,551), 2011 (n = 24,218), and 2012 (n = 41,726), and seasons categorized as winter, spring, summer, and fall. When data aggregated per years were analyzed, the difference between the two sexes was significant (P < 0.005) in favor of the male gender, whereas no influence of the season was evidenced. Real-time polymerase chain reaction did not evidence any difference between the mean values of frequency of Y chromosome–bearing sperm detected in three sperm batches of the same bulls analyzed immediately after thawing (51.1 ± 2.1), nor a difference with respect to the theoretical 1:1 ratio was reported after sperm analysis of one batch of sperm of the bulls analyzed after swim-up and immediately after thawing (50.1 ± 2.1 and 49.8 ± 1.8, respectively). The results are consistent with the observation of the farmers who often report a skewed sex ratio of the calves being born with AI in favor of the male gender. However, we have not evidenced differences in the primary sex ratio with respect to the theoretical 1:1 ratio both at thawing and after swim-up, thus demonstrating that the freezing procedure itself does not impact selectively on the survival of the X or Y chromosome–bearing sperm. Therefore, we hypothesize that the difference between genders observed after AI is more likely due to the events occurring after fertilization, which can comprise an impaired function of the X- or Y-bearing sperm with consequences on embryo development or a maternal influence.

Nuclear DNA fragmentation negatively affects zona binding competence of Y bearing mouse spermatozoa

To investigate the influence of sperm DNA integrity on the zona binding ability of mouse spermatozoa in relation to their sex chromosomal constitution. In this prospective experimental study, the sperm DNA fragmentation was induced by exposing testicular area of Swiss Albino mice (Mus musculus) to different doses of γ-radiation (0, 2.5, 5.0 and 10.0Gy). Sperm DNA fragmentation was quantified by single cell gel electrophoresis (comet assay). In vitro sperm zona binding assay was performed and the numbers of zona bound X and Y bearing spermatozoa were determined using fluorescence in situ hybridization (FISH). The assessment of zona pellucida bound X and Y-bearing spermatozoa using fluorescence in situ hybridization has revealed a unique binding pattern. The number of zona bound Y-spermatozoa declined significantly (P < 0.01 to 0.0001) with increase in the DNA damage. The skewed binding pattern of X and Y-bearing sperm was strongly correlated with the extent of sperm DNA damage. The zona pellucida may have a role in preventing DNA damaged mouse sperm binding especially towards Y-bearing sperm. However, the exact mechanism behind this observation needs to be elucidated further.

Decreased Viability of Y-Chromosome Bearing Spermatozoa Treated with Dioxin In Vitro.

Decreased Viability of Y-Chromosome Bearing Spermatozoa Treated with Dioxin In Vitro.

A preparatory technique for semen selection

OBJECTIVE: The desire to control the gender is apparent across time and culture. From nobility of medieval Europe striving for male heirs, to modern day dairy farmers seeking female calves to increase productivity in their herds, there are many motivations driving people to discover a practical technique to control sex. Previous research has sought a technique that will not only allow for the determination of the offspring preconceived but that also is robust and practical in a wide variety of settings. To date, Flow Cytometry, is the only technique capable of producing a semen sample with a 90% concentration of either X or Y bearing spermatozoa. However, flow cytometry is costly in both time and equipment, has safety concerns, and results in a small inseminatable sample. The current study reports of a new, proprietary methodology for inexpensive semen selection.DESIGN: Laboratory based study on semen separation using a animal model.MATERIALS AND METHODS: Semen samples from 14 bulls were obtained and prepared in extender before being exposed to 4 proprietary chemical solutions (A-D) using the new proprietary Semen Selection Chamber (SSC). Samples were monitored for changes in motility and concentration measurements at 1, 3 and 6 hours. Samples were then collected and processed for Fluorescent in situ Hybridization analysis.RESULTS: As expected, there were differences in both cell concentration and motility in each of the 4 chemical solutions (P < .001), with solutions, B and C, the solutions closest to normal body physiology, having the highest concentration of motile cells. Further, there were shifts in the sex ratios in at least three of the solutions. Solution D showed statistically higher ratios (P < .001) of Y bearing sperm averaging a 35:65 ratio (X:Y). Solutions A and B showed a trend toward higher X bearing ratios with an average of 56:44.CONCLUSIONS: While sex selection with the SSC yielded significantly lower ratios of X:Y sperm than that reported in the literature for flow cytometry (reported as high as 90%), the data from the present study suggests that the SSC can significantly shift the sex ratios of semen samples during processing. Further, given the average expense of a flow cytometry sorted sample ($500 for animals and $1500 or more in humans) verses the <$10/sample cost of the SSC sorting, further work with the SSC is justified to determine if it can increase birth rates of the selected sex. OBJECTIVE: The desire to control the gender is apparent across time and culture. From nobility of medieval Europe striving for male heirs, to modern day dairy farmers seeking female calves to increase productivity in their herds, there are many motivations driving people to discover a practical technique to control sex. Previous research has sought a technique that will not only allow for the determination of the offspring preconceived but that also is robust and practical in a wide variety of settings. To date, Flow Cytometry, is the only technique capable of producing a semen sample with a 90% concentration of either X or Y bearing spermatozoa. However, flow cytometry is costly in both time and equipment, has safety concerns, and results in a small inseminatable sample. The current study reports of a new, proprietary methodology for inexpensive semen selection. DESIGN: Laboratory based study on semen separation using a animal model. MATERIALS AND METHODS: Semen samples from 14 bulls were obtained and prepared in extender before being exposed to 4 proprietary chemical solutions (A-D) using the new proprietary Semen Selection Chamber (SSC). Samples were monitored for changes in motility and concentration measurements at 1, 3 and 6 hours. Samples were then collected and processed for Fluorescent in situ Hybridization analysis. RESULTS: As expected, there were differences in both cell concentration and motility in each of the 4 chemical solutions (P < .001), with solutions, B and C, the solutions closest to normal body physiology, having the highest concentration of motile cells. Further, there were shifts in the sex ratios in at least three of the solutions. Solution D showed statistically higher ratios (P < .001) of Y bearing sperm averaging a 35:65 ratio (X:Y). Solutions A and B showed a trend toward higher X bearing ratios with an average of 56:44. CONCLUSIONS: While sex selection with the SSC yielded significantly lower ratios of X:Y sperm than that reported in the literature for flow cytometry (reported as high as 90%), the data from the present study suggests that the SSC can significantly shift the sex ratios of semen samples during processing. Further, given the average expense of a flow cytometry sorted sample ($500 for animals and $1500 or more in humans) verses the <$10/sample cost of the SSC sorting, further work with the SSC is justified to determine if it can increase birth rates of the selected sex.

Exposure to Persistent Organochlorine Pollutants Associates With Human Sperm Y:X Chromosome Ratio

BACKGROUND: During the last decades, there has been concern that exposure to endocrine disruptors, such as persistent organochlorine pollutants (POPs), may contribute to sex ratio changes in offspring of exposed populations. METHODS: To investigate whether exposure to 2,2'4,4'5,5'-hexachlorobiphenyl (CB-153) and dichlorodiphenyl dichloroethene (p,p'-DDE) affect Y:X chromosome proportion, semen of 149 Swedish fishermen, aged 27–67 years, was investigated. The men provided semen and blood for analysis of hormone, CB-153 and p,p'-DDE levels. The proportion of Y- and X-chromosome bearing sperm in semen samples was determined by two-colour fluorescence in situ hybridization (FISH) analysis. RESULTS: Log transformed CB-153 as well as log transformed p,p'-DDE variables were both significantly positively associated with Y chromosome fractions (P-values=0.05 and <0.001, respectively). Neither age, smoking nor hormone levels showed any association with Y-chromosome fractions. CONCLUSIONS: This is the first study to indicate that exposure to POPs may increase the proportion of ejaculated Y-bearing spermatozoa. These data add to the growing body of evidence that exposure to POPs may alter the offspring sex ratio. (Less)

Exposure to persistent organochlorine pollutants associates with human sperm Y:X chromosome ratio

During the last decades, there has been concern that exposure to endocrine disruptors, such as persistent organochlorine pollutants (POPs), may contribute to sex ratio changes in offspring of exposed populations. To investigate whether exposure to 2,2'4,4'5,5'-hexachlorobiphenyl (CB-153) and dichlorodiphenyl dichloroethene (p,p'-DDE) affect Y:X chromosome proportion, semen of 149 Swedish fishermen, aged 27-67 years, was investigated. The men provided semen and blood for analysis of hormone, CB-153 and p,p'-DDE levels. The proportion of Y- and X-chromosome bearing sperm in semen samples was determined by two-colour fluorescence in situ hybridization (FISH) analysis. Log transformed CB-153 as well as log transformed p,p'-DDE variables were both significantly positively associated with Y chromosome fractions (P-values = 0.05 and <0.001, respectively). Neither age, smoking nor hormone levels showed any association with Y-chromosome fractions. This is the first study to indicate that exposure to POPs may increase the proportion of ejaculated Y-bearing spermatozoa. These data add to the growing body of evidence that exposure to POPs may alter the offspring sex ratio.

Effect of ejaculate, bull, and a double swim-up sperm processing method on sperm sex ratio.

Offspring gender preselection has applications of considerable economic, health and ecological interest. In this study we analysed modifications of the percentages of spermatozoa bearing Y and X chromosomes when semen samples are submitted to a double swim-up technique as a possible method for producing embryos of known sex with in vitro fertilisation protocols. As an initial experiment to provide accurate evaluation of the method we determined the possible incidence of natural deviations in the primary sex ratio between bulls or ejaculates, analysing the percentage of Y-chromosome DNA bearing spermatozoa (%Y-CDBS) with a polymerase chain reaction (PCR) amplification of X- and Y-specific fragments. Ejaculates were tested by direct semiquantitative PCR sexing and by sexing blastocysts produced in vitro with these spermatozoa. Bulls and ejaculates did not have any effect on the %Y-CDBS or on the sex ratio of embryos produced in vitro using these ejaculates. However, our double swim-up sperm preparation method produced differences in %Y-CDBS in some of the sperm fractions, suggesting that there are intrinsic differences in capacitation of X- and Y-bearing spermatozoa that might be used to produce embryos of the desired sex with in vitro fertilisation.

X-Y Sperm Selection: Fact or Fiction?

Selecting the gender of offspring has given rise to various and sometimes amusing stories. But regardless of which prefertilisation technique is used to influence the sex ratio of offspring it must fulfill certain criteria. First of all it must achieve a complete separation of the X and Y bearing sperm in sufficient quantities. Secondly sperm must be viable after separation and capable of fertilising. Sex preselection methods can be divided into two general groups which either separate spermatozoa on the basis of subtle physical or kinetic features or those which rely on distinctive nuclear characteristics unique either to X or Y chromosome bearing sperm. These, in turn, can be divided into in vivo methods designed to produce optimal conditions for fertilisation by either the X or Y bearing sperm, or in vitro sperm separation methods designed to separate X or Y bearing sperm. According to all published data, the different separation techniques have been shown not to be very effective. Only sex selection of spermatozoa by chromatin differences (cell sorting by flow cytometry) has demonstrated a significant enrichment of the X bearing sperm.

Status of oocytes and embryos of X‐autosome translocation carrier sows

The impact of an X‐autosome translocation t(Xp+;14q‐), on ovulation, fertilization and embryo survival in carrier sows, was examined and compared with these parameters of normal sows. Corpora lutea counts during week‐2 and week‐4 of gestation were similar in normal and carrier sows (14.4 ± 1.36 and 15.5 ±2.18) although embryo recovery (11.0 ± 1.87 and 6.0 ± 1.47) was lower than that from normal sows (12.8± 1.46 and 11.5 ±0.87), at these stages. Among the embryos karyotyped from the week‐2 embryos of carrier sows, 42 % were normal, 26.4% were carriers and 31.6% were of unbalanced chromosome make‐up, and of the week‐4 embryos of carriers, 33.3% were normal, 57.1% were carriers and 9.1% were chromosomally unbalanced females. The preponderance of females among the unbalanced embryos recovered at week‐2 of gestation (11_ and 1_) and the total absence of males among those recovered at week‐4, suggest that oocytes with unbalanced chromosome constitution are eliminated before week‐2 of gestation if they are fertilized by Y bearing sperm, and that the unbalanced oocytes fertilized by X bearing sperm survive up to the peri‐attachment stage even though all chromosomally unbalanced embryos are eliminated before term regardless of their sex.

Birth of piglets preselected for gender following in vitro fertilization of in vitro matured pig oocytes by X and Y bearing spermatozoa sorted by high speed flow cytometry

Birth of piglets preselected for gender following in vitro fertilization of in vitro matured pig oocytes by X and Y bearing spermatozoa sorted by high speed flow cytometry

Evidence That Y-chromosome Bearing Sperm Persist Functionally in the Hemizona Assay Longer than X-chromosome Bearing Sperm

Evidence That Y-chromosome Bearing Sperm Persist Functionally in the Hemizona Assay Longer than X-chromosome Bearing Sperm

Enhanced separation of X and Y bearing sperm cells by a combined density gradient centrifugation evaluated by fluorescence in situ hybridization of the Y‐chromosome

Fluorescent in situ hybridization of decondensed sperm cells was used to evaluate the effectiveness of separating X- and Y chromosome bearing sperm cells using a combination of Percoll and NycoPrep media. Semen samples from seven healthy men were divided into three equal aliquots. One aliquot served as an untreated control, the other two were either applied to a seven-step Percoll gradient (100%-40%), or to a seven-step Percoll gradient (100%-40%) underlayered with 100% NycoPrep for sperm purification. After centrifugation Y-bearing sperm cells in the pellet and in the control sample was determined by fluorescent in situ hybridization. A significantly reduction of Y-bearing sperm cells were observed in the pellet of the Percoll + NycoPrep centrifugation (39.3% Y-bearing sperm cells) compared to the control sample and to Percoll centrifugation without NycoPrep. The Percoll centrifugation without NycoPrep did not show a significant reduction of Y-bearing sperm cells in the pellet compared to the control sample. By the addition of a medium with a density higher than 100% Percoll a significantly increased separation of X and Y-bearing sperm cells can be achieved. This study opens new perspectives for improving separation of X- and Y-bearing spermatozoa by simple centrifugations. The described centrifugation technique can be applied in connection with preimplantation diagnosis in order to create more pre-embryos of the desired gender.

Non-disjunction in human sperm: results of fluorescence in situ hybridization studies using two and three probes.

Fluorescence in situ hybridization using two or three probes was utilized to estimate the incidence of diploidy, the incidence of disomy for the sex chromosomes and chromosomes 16 and 18, and the proportion of Y- and X-chromosome bearing sperm, in a series of normal males. Our results demonstrate the importance of using an approach capable of distinguishing disomy from diploidy, as most donors had levels of diploidy higher than the disomy levels of individual chromosomes. Our analyses suggest the existence of chromosome-specific mechanisms of paternal non-disjunction, as sex chromosome disomy was approximately 1.5 times as common as disomy 16, and over two times as common as disomy 18. In studies of gametic sex ratio, we found little evidence for marked deviation from an expected 1:1 ratio.

Natural family planning and sex selection: Fact or fiction?

Determining sex of offspring by timing of intercourse has been a subject of intense interest for the lay public and professional community. This metaaanalysis of couples practicing natural family planning provides an opportunity to evaluate sex ratios in relation to the timing of conception with several parameters, including basal body temperature shift and peak mucus as markers of ovulation. Data from six studies show a statistically significant lower proportion of male births among conceptions that occur during the most fertile time of the cycle.

Improvement of flow cytometry analysis and sorting of bull spermatozoa by optical monitoring of cell orientation as evaluated by DNA specific probing

Flow cytometry is a potential method for the separation of X and Y bearing spermatozoa, on the basis of their relative DNA content evaluated by the fluorescence emission intensity due to specific fluorochrome DNA staining. However, spermatozoa DNA is highly condensed and nuclei exhibit flat non spherical shape, which can produce artefacts impeding accurate analysis. In order to avoid these limitations, decondensation of DNA performed by enzymatic treatment and a modification of the flow cytometer that orients the spermatozoa relative to the laser beam are generally used. In this work, we describe alternative methods and materials for selection of 1) decondensed and thus dead spermatozoa without orientation, sorted on the basis of only the 10% spermatozoa containing the least DNA (expected Y) and the 10% spermatozoa containing the more DNA (expected X), or 2) native spermatozoa homogeneously oriented using a simultaneous measurement of Axial light loss (extinction) and Forward angle light scatter. For testing enrichment of each selected fraction we have worked out a molecular hybridization procedure using X and Y specific DNA probes. We analyse and sort bull spermatozoa on these basis: the purity obtained for these fractions is 80% without orientation after enzymatic treatment, and 70% on live spermatozoa "optically" oriented.

Treatment of sperm to predetermine sex

There are countless reports of “success”, and occasionally of “failure”, to isolate populations of sperm enriched for either X-chromosome bearing sperm or Y-chromosome bearing sperm (hereafter called X-sperm and Y-sperm), or to induce a skewed sex ratio at birth. Unfortunately, most reports are unreliable because the experiment contained inadequate replication, and thus was destined to be inconclusive; used questionable laboratory procedures to evaluate success; or some data were unavailable or were excluded. Furthermore, failures usually are not reported. Specific and statistically robust laboratory tests to evaluate the ratio of X- to Y-sperm in starting and isolated fractions now are available. This should facilitate progress, provided valid experiments are conducted. Ultimately, efficacy of a procedure for altering sex ratio at birth must be established. Presently, only the use of columns of human serum albumin for treatment of human sperm appears to be successful. However, flow sorting may be applicable when only a few doses of sperm are needed for in vitro fertilization or artificial insemination, and reduced fertility is acceptable. Development of a technique for conveniently isolating large populations of cells highly enriched for either X- or Y-sperm, of normal fertility, or for differentially blocking fertilizing capacity of one type of sperm remains an intellectual challenge.