Abstract
The objectives of this study are to determine whether there are differences in the number of ovulations between the left and right ovaries, and the male embryo implantation between the left and right uterine horn in goats. Twentyfour multiparous goats were superovulated and used as donors. An intra-vaginal progesterone-impregnated CIDR device was inserted to the estrous synchronization donors for 13 days during the early breeding season. Super ovulations were induced by eight doses of Folltropin with its concentrations decreasing starting at days 10-13 of the estrus cycle. All goats were inseminated with 6×108 sperm twice via artificial insemination 42 h and 50 h after removal of CIDR. Semen from three goats, that on average sired an even sex ratio (1:1) for X and Y sperm, were mixed and deposited into the cervix. The embryos from the left and right uterine horn were collected by surgery on the sixth day following insemination and evaluated based on morphological evaluation of developmental stage and quality. The numbers of total corpora lutea, eggs, and embryos per right ovary (6.3 ± 1.2, 5.7 ± 1.7, 5.1 ± 2.1) was significantly greater than the left ovary (5.1 ± 1.4, 4.3 ± 2.0, 4.0 ± 1.9). One hundred ninety-eight embryos (95 from the left uterine horn and 103 from the right uterine horn) were sex-typed by DNA analyses for the amelogenin gene. There were significant differences (p<0.05) in the sex ratio of embryos between the right uterine (69M / 34F) and the left uterine (45M / 50F) horns. In conclusion, the male ratio of embryos harvested from the right uterine horn of superovulated goats by insemination with 50% X- and 50% Y-bearing sperm was significantly higher than the left uterine horn. The ovulation capacity of the right ovary was more than the left ovary.
Highlights
Sex determination is important for reproduction of all mammals
Previous studies in mice indicated that ovulation rate, number of fetuses, and total fetal and placental weight were higher in the right than left ovary [3], and ovarian and uterine function is asymmetrical [4]
Improved maternal health may provide optimal conditions for ovum of the right ovary [5]. This might regulate the development of the zona pellucida, which subsequently increases the likelihood of fertilization by a Y- bearing sperm. These results suggest that an imbalance between the left and right uterine horns might affect embryonic gender and development
Summary
Sex determination is important for reproduction of all mammals. The determination of gender for an offspring depends on whether an Xor a Y - bearing sperm fertilizes the oocyte. The maternal dominance hypothesis demonstrates that females who are more dominant than others are more likely to conceive sons [2], revealing selective differences for X- or Y- bearing sperm in different species It remains to be seen if these selective differences are due to the differences of left and right uterine horns, or the number of oocytes. Improved maternal health may provide optimal conditions for ovum of the right ovary [5] This might regulate the development of the zona pellucida, which subsequently increases the likelihood of fertilization by a Y- bearing sperm. Overall, these results suggest that an imbalance between the left and right uterine horns might affect embryonic gender and development
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