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Loss- and Gain-of-function Approach to Investigate Early Cell Fate Determinants in Preimplantation Mouse Embryos
Published on: June 6, 2016
Male advantage observed for in vitro fertilization mouse embryos exhibiting early cleavage
Yosuke Kawase1, Takanori Tachibe1, Nobuo Kamada1
1Chugai Institute for Medical Science, Inc Gotemba Japan.
Purpose:
Mouse embryos forming blastocoele early vs those forming late are predominantly male. We examined whether the male advantage could be recognized at an earlier stage of development.
Methods:
The IVF embryos were classified into early, intermediate, and late development groups based on the time of the third cleavage, and the Zfy and Xist genes were detected to identify their sex in the classified embryos. Furthermore, embryos that were classified based on the time of the third cleavage were transferred to recipient animals and the sex ratio of the fetuses was determined at birth.
Results:
Approximately 90% of the early-developing embryos that exhibited third cleavage as early as 47 hours after insemination were male when analyzed using PCR at the blastocyst stage. PCR analysis showed that 61% of the intermediate-developing embryos (third cleavage occurring 48-50 hours after insemination) and 45% of late-developing embryos (third cleavage occurring at 51 hours or later postinsemination) were male. After embryo transfer, the early-developing embryos produced 80% males, while intermediate- and late-developing embryos produced 56% and 45% males, respectively.
Conclusions:
Male embryos tend to develop faster than female embryos during early stage of preimplantation in mice.
Insights
Early-developing mouse embryos are predominantly male. This study investigated if male embryos exhibit faster development during the early preimplantation stage, confirming a male developmental advantage.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Genetics
Background:
- Early blastocoele formation in mouse embryos correlates with a male predominance.
- Understanding sex-biased developmental rates is crucial for reproductive science.
Purpose of the Study:
- To determine if the male advantage in mouse embryos is detectable at earlier developmental stages.
- To investigate the relationship between the timing of the third cleavage and embryonic sex.
Main Methods:
- In vitro fertilization (IVF) mouse embryos were classified into early, intermediate, and late development groups based on the timing of their third cleavage.
- Sex of classified blastocysts was determined using Polymerase Chain Reaction (PCR) to detect Zfy (male) and Xist (female) genes.
- Embryo transfer to recipient females was performed to assess the in vivo sex ratio of fetuses from different developmental groups.
Main Results:
- Approximately 90% of early-developing embryos (cleavage at 47 hours) were male at the blastocyst stage.
- Intermediate (48-50 hours) and late-developing (≥51 hours) embryos showed male percentages of 61% and 45%, respectively.
- In vivo, early-developing embryos resulted in 80% males, while intermediate and late groups yielded 56% and 45% males, respectively.
Conclusions:
- Male mouse embryos exhibit accelerated development during the early preimplantation stage compared to female embryos.
- The timing of the third cleavage serves as an indicator of embryonic sex, with faster cleavage suggesting male development.
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