Sperm kinetics and morphology before and after fractionation on discontinuous Percoll gradient for sex preselection: computerized analyses

Efficacy of a commercially available post-thaw bovine semen sexing kit in both single-ovulating and hyperstimulated cows

Currently, there are few inexpensive, reliable, effective methods for commercially separating X- and Y-chromosome bearing fresh and frozen bovine sperm. The objective of these experiments was to determine the efficacy of a commercially available post-thaw bovine semen sexing kit, HeiferPlus (HP) which claims to alter the sex ratio in favor of female calves following artificial insemination. Three trials included the insemination of hyperstimulated cows with Control or HP-treated semen, non-surgical embryo collection on Day 7, and a combined PCR/dot blot assay to determine embryo sex. Chi-square analysis showed that the Control group produced a greater proportion (p<0.0005) of female embryos than the HP group. There were no differences in the proportions of transferable compared with degenerate embryos or in number of ovulations, embryos, and unfertilized ova collected from Control compared with HP groups. When treatments were combined, one of the two bulls used in the hyperstimulation studies produced an overall greater proportion of females (p<0.05), suggesting a bull effect. Another trial involved the insemination of cows synchronized via OvSynch((R)) with fetal sexing via ultrasonography. Results of these studies indicated that HP semen sexing kit did not alter the sex ratio in favor of females in either hyperstimulated or single-ovulating cows; however, potential bull effects may be further evaluated to understand the capacity of HP with semen from specific bulls. Additionally, perhaps the sex of the surviving embryo can be manipulated by the maternal side, through ovarian, hormonal, oviductal, or uterine influences.

Assessment of bovine X- and Y-bearing spermatozoa in fractions by discontinuous percoll gradients with rapid fluorescence in situ hybridization

This study was designed to apply the method of discontinuous Percoll gradients for sex preselection in bovine semen by using a current developed molecular technique, fluorescence in situ hybridization (FISH). In addition, we attempted to amplify the level of enrichment of X- or Y-bearing spermatozoa by treating for activating sperm motility performance with 10 mM caffeine. Bovine spermatozoa were fractionated on Percoll gradients into two major subpopulations of motile spermatozoa (bottom fraction) and weak motile spermatozoa (top fraction). The percentage of Y-bearing spermatozoa in the top fraction (52.9%) slightly exceeded and that in the bottom fraction (44.3%) decreased significantly (P<0.001) compared with the theoretical ratio (50:50). Washing sperm with BO medium affected a deviation between the two sex populations, whereas semen activated with caffeine showed no difference in the percentage of X- and Y-bearing spermatozoa in both fractions compared with the theoretical ratio (50:50). These results show that the proportion of X- and Y-bearing bovine spermatozoa can deviate after discontinuous Percoll gradients, although the proportion of X- and Y-bearing bovine spermatozoa was affected by sperm motility of the sample applied.

Sperm pre-incubation prior to insemination affects the sex ratio of bovine embryos produced in vitro

The objective of the present study was to determine whether sperm incubation prior to oocyte insemination in vitro affects the sex ratio of resulting blastocyst. Cumulus-oocyte-complexes (COCs) collected from slaughterhouse ovaries were matured in vitro and inseminated with frozen-thawed semen of three proven artificial insemination (AI) bulls pre-incubated in vitro in Sperm-Talp for 6 and 24 h. On day-9 blastocysts were collected and processed for sex determination. More than 80% of blastocyst were successfully sexed. There were no significant differences in cleavage and blastocyst rates using sperm pre-incubated for 6 h as compared with the 0-h pre-incubation control group. The cleavage and blastocyst rates were significantly lower in the 24-h pre-incubation group. The male to female ratio, when compared with the theoretical 1 : 1, differed significantly in favour of females among hatched (viable) blastocysts derived from sperm pre-incubated for 24 h prior to insemination as well as among all blastocytsts in the 6-h group. Moreover, when the sperm treatment was considered, the sex ratio was affected only among hatched blastocysts in 24-h pre-incubation group. It was concluded that prolonged sperm pre-incubation influences the rate of development and the sex ratio among hatched blastocysts.

The 50 million missing women

The epidemic of gender selection is ravaging countries like India & China. Approximately fifty million women are "missing" in the Indian population. Generally three principle causes are given: female infanticide, better food and health care for boys and maternal death at childbirth. Prenatal sex determination and the abortion of female fetuses threatens to skew the sex ratio to new highs. Estimates of the number of female fetuses being destroyed every year in India vary from two million to five million. This review from India attempts to summarize all the currently available methods of sex selection and also highlights the current medical practice regards the subject in south-east Asia.

The use of transmigration and spermac stain to evaluate epididymal cat spermatozoa

Epididymal spermatozoa of domestic cats were diluted with TEST medium and frozen. The parameters - estimated percentage of motile spermatozoa, concentration of spermatozoa, cell morphology and transmigration rate (TMR) - were evaluated before freezing and after thawing. Transmigration is a new method to measure the percentage of spermatozoa that consistently move forward, and has not been investigated with cat spermatozoa until now. Estimated percentage of motile spermatozoa averaged 65%, TMR was 76%, concentration of spermatozoa was 30,000 microl(-1) and the incidence of morphologically abnormal spermatozoa averaged 58% before freezing. After thawing, the estimated number of motile spermatozoa declined by 22%, but TMR remained at 76%. The TMR did not correlate with estimated motility but mostly was higher than the latter, which is postulated to be caused by the mobilizing effect of the countercurrent in the transmigration apparature. The estimated percentage of motile cells in the target chamber of the transmigration apparature was improved by using phosphate-buffered saline (PBS) as transmigration medium. Morphology was assessed both after fixation of spermatozoa in Hancock solution and after staining of smears with Spermac. Spermac did not stain all protoplasmic droplets but proved to be more suitable for the routine examination of acrosomal morphology after thawing.

Variation of docosahexaenoic acid content in subsets of human spermatozoa at different stages of maturation: implications for sperm lipoperoxidative damage

The oxidation of phospholipid-bound docosahexaenoic acid (DHA) has been shown to be one of the major factors that limit the motile life span of sperm in vitro. Sperm samples show high cell-to-cell variability in life span and, consequently, in susceptibility toward lipid peroxidation. Therefore, we postulated that there is also cell-to-cell variability in DHA concentration in human spermatozoa. In this study, the concentration of DHA in subsets of human spermatozoa isolated by a discontinuous Percoll density gradient was determined by gas chromatography. Four subsets of human spermatozoa were isolated using a discontinuous Percoll gradient: fraction 1 was enriched in immature germ cells and immature sperm, fractions 2 and 3 contained, mostly, immature sperm with cytoplasmic droplets, and fraction 4 contained, for the most part, morphologically normal sperm, as determined by histochemical analysis. The results indicated that there were significant differences in DHA content in sperm from all 4 fractions. DHA content in sperm from fraction 1 was 2.5-fold higher than that found in fraction 4. DHA content in mouse sperm obtained from the seminiferous tubules was 3-fold higher than that found in mouse sperm obtained from the epididymis, consistent with the findings observed in ejaculated human sperm. The results of this study indicate (i) there is cell-to-cell variability in the concentration of DHA in human sperm and (ii) that there is a net decrease in DHA content in sperm during the process of sperm maturation.