Mouse Embryo Development Research Articles

Tracing the origin of the placental trophoblast cells in mouse embryo development†.

The placenta, which originates from the trophectoderm (TE), is the first organ to form during mammalian embryogenesis. Recent studies based on bioinformatics analysis have revealed that heterogeneous gene expression initiates cell-fate decisions and directs two distinct cell fates by modulating the balance of pluripotency and differentiation as early as the four-cell stage. However, direct developmental evidence to support this is still lacking. To address at which stage the cell fate of the TE and inner cell mass (ICM) is determined, in this study, we administered a microinjection of Cre mRNA into a single blastomere of the mTmG mouse at different cleavage stages before implantation to examine the distributions of the descendants of the single-labeled cell in the mouse fetus and the placenta at E12.5. We found that the descendants of the labeled cells at the two-cell stage contributed to both the placenta and the fetus. Notably, the derivatives of the labeled cells at the four-cell stage fell into three categories: (1) distributed in both embryonic and extraembryonic lineages, (2) distributed only in mouse placental trophoblast layers, or (3) distributed only in the lineage derived from the ICM. In addition, these results fell in line with single-cell studies focusing on gene expression patterns that characterize particular lineages within the blastocyst. In conclusion, this study shows that the four-cell blastomeres differ in their individual developmental properties insofar as they contribute to either or both the ICM and trophoblast fate.

Controlled ploidy reduction of pluripotent 4n cells generates 2n cells during mouse embryo development.

Cells with high ploidy content are common in mammalian extraembryonic and adult tissues. Cell-to-cell fusion generates polyploid cells during mammalian development and tissue regeneration. However, whether increased ploidy can be occasionally tolerated in embryonic lineages still remains largely unknown. Here, we show that pluripotent, fusion-derived tetraploid cells, when injected in a recipient mouse blastocyst, can generate diploid cells upon ploidy reduction. The generated diploid cells form part of the adult tissues in mouse chimeras. Parental chromosomes in pluripotent tetraploid cells are segregated through tripolar mitosis both randomly and nonrandomly and without aneuploidy. Tetraploid-derived diploid cells show a differentiated phenotype. Overall, we discovered an unexpected process of controlled genome reduction in pluripotent tetraploid cells. This mechanism can ultimately generate diploid cells during mouse embryo development and should also be considered for cell fusion-mediated tissue regeneration approaches.

3D gyratory rocker may accelerate embryonic ZO1 expression and further embryonic development in mouse embryos

3D gyratory rocker may accelerate embryonic ZO1 expression and further embryonic development in mouse embryos

Inhibition of line-1 transposition blocks telomere elongation and downregulates totipotency genes during mouse embryo development

Inhibition of line-1 transposition blocks telomere elongation and downregulates totipotency genes during mouse embryo development

Insulin and IGF-1 does not alter the morphokinetics of mouse embryo development

Objective To assess if there is a benefit to adding either IGF-1 or insulin to culture medium in terms of mouse embryo development using time-lapse morphokinetics. Design Prospective study. Materials and methods A total of 305 commercially obtained frozen mouse embryos (B6D2F1 & B6C3F1 hybrid) were thawed and cultured in (1) One-Step medium only, (2) One-Step medium with 100ng/mL insulin, and (3) One-Step medium with 100ng/mL IGF-1, using an EmbryoScope time lapse incubator at 37°C, 5.5% CO2, and 6.0% O2. The EmbryoScope was set to record images of each embryo every 10 minutes for 6 days of culture. The following time points were annotated: 2cell (t2), 3cell (t3), 4cell (t4), 5cell (t5), 6cell (t6), 7cell (t7), 8cell (t8), start of compaction (tSC), morula (tsM), start of blastulation (tSB), blastocyst (tB), expanded blastocyst (tEB) and hatching blastocyst (tHB). The 2-cell stage was considered as time zero since the exact time of insemination was unknown. All time points were statistically compared between each of the three groups. Blastocyst development rates for each group were also compared. Results A total of 304 blastocysts developed from the 316 embryos cultured, yielding an overall blastocyst development rate of 96.2%.When comparing the blastocyst development rate between the 3 groups, there were no significant differences between the One-Step and IGF-1 media groups (99.1% vs 96.2%). However, the insulin group showed significantly lower blastocyst rates when compared to the controls (93.3% vs 99.1%; p=0.02). There were no statistically significant differences in any of the time points measured between the One-Step, insulin and IGF-1 groups. Conclusions The data indicates that there is no beneficial effect of adding insulin or IGF-1 to culture media for mouse embryo development. Neither insulin not IGF-1 had any effect on the morphokinetics of these embryos. However, culture of mouse embryos in insulin supplemented media resulted in a lower blastocyst development rate compared to One-Step media. Ongoing studies are underway using a more sensitive mouse strain to see whether any changes in morphokinetics may be detected. Disclosures Nothing to disclose Funding None

Antioxidants increase blastocyst cryosurvival and viability post vitrification

STUDY QUESTION: What is the effect of antioxidants acetyl-L-carnitine, N-acetyl-L-cysteine and α-lipoic acid (A3) in vitrification and warming solutions on mouse blastocyst development and viability? SUMMARY ANSWER: The combination of three antioxidants in vitrification solutions resulted in mouse blastocysts with higher developmental potential in vitro and increased viability as assessed by both an outgrowth model in vitro and fetal development following uterine transfer. WHAT IS KNOWN ALREADY: The antioxidant combination of acetyl-L-carnitine, N-acetyl-L-cysteine and α-lipoic acid present in IVF handling and embryo culture media has significant beneficial effects on mouse embryo and fetal development, especially under oxidative stress. STUDY DESIGN, SIZE, DURATION: The study was a laboratory-based analysis of an animal model. Rapid cooling through vitrification was conducted on F1 mouse blastocysts, with antioxidants (A3) supplemented in vitrification and/or warming solutions, followed by culture and embryo transfer. PARTICIPANTS/MATERIALS, SETTINGS, METHODS: Pronucleate oocytes were collected and cultured in groups to Day 4 blastocysts. Expanded blastocysts were vitrified and warmed in solutions with and without the A3 antioxidants and cultured for a further 24 h. Blastocyst cell number and allocation, apoptosis and histone acetylation levels were all quantified, and viability through outgrowths and transfers assessed. MAIN RESULTS AND THE ROLE OF CHANCE: Mouse blastocysts vitrified with no antioxidants had significantly lower cell numbers (P < 0.001) and higher apoptotic cells (P < 0.05) compared to non-vitrified embryos. Addition of combined A3 antioxidants to the vitrification and warming solutions resulted in a significant increase in inner cell mass cell (ICM) number (P < 0.001) and total cell number (P < 0.01), and an increase in outgrowth area (P < 0.05), which correlated with the increased fetal weight (P < 0.05), crown rump length (P < 0.05) and limb development (P < 0.05) determined following transfer compared to embryos with no antioxidants. Furthermore, while blastocyst vitrification significantly reduced acetylation levels (P < 0.05) compared to non-vitrified embryos, the inclusion of A3 antioxidants helped to ameliorate this. LIMITATIONS, REASONS FOR CAUTION: Embryo development was only examined in the mouse. WIDER IMPLICATIONS OF THE FINDINGS: Results in this study demonstrate that vitrification and warming of blastocysts have significant detrimental effects on embryo histone acetylation and subsequent viability. The presence of antioxidants in the vitrification solutions helps to alleviate the negative effects of cryopreservation. Our data indicate that antioxidants need to be present in the medium at the time of exposure to increased oxidative stress associated with vitrification and that prior exposure (i.e. during culture or IVF alone) is insufficient to protect cells against cryo-induced injury. Hence, A3 antioxidants may assist in maintaining the viability of vitrified human embryos in ART through the reduction of oxidative stress. STUDY FUNDING/COMPETING INTEREST(S): This work was funded by a research grant from Vitrolife AB (Sweden). The authors have no conflict of interest to declare.

Does supplementation of media with insulin or insulin-like growth factor 1 (IGF-1) enhance morphokinetics of mouse embryo development?

Does supplementation of media with insulin or insulin-like growth factor 1 (IGF-1) enhance morphokinetics of mouse embryo development?

Tris(1,3-dichloro-2-propyl) phosphate disturbs mouse embryonic development by inducing apoptosis and abnormal DNA methylation.

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is a kind of additive flame retardants (FRs) and was found to affect early embryonic development in zebrafish; however, there are few studies to investigate whether TDCPP will disturb the development of early mouse embryos. In our studies, we used mouse embryos as models to study the toxicology of TDCPP on the early embryos. The results showed that TDCPP disturbed the development of early mouse embryos in a dose-dependent manner. 10 μM TDCPP decreased the blastocyst formation and 100 μM TDCPP was a lethal concentration for the mouse embryos. We proved that TDCPP was detrimental to embryonic development potential by increasing the reactive oxygen species level and inducing early apoptosis. Furthermore, TDCPP changed the DNA methylation patterns of imprinted genes in treated blastocysts. The methylation of H19 and Snrpn promoter regions was increased from 37.67% to 46.00% and 31.56% to 44.38% in treated groups, respectively. In contrast, Peg3 promoter region methylation was declined from 86.55% to 73.27% in treated embryos. Taken together, our results demonstrated that TDCPP could adversely impair the early embryonic development in mouse. Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.

PKCδ promotes fertilization of mouse embryos in early development via the Cdc25B signaling pathway.

Protein kinase C type δ (PKCδ) is involved in B-cell signaling and the regulation of growth, apoptosis and differentiation of a variety of cell types. Cell division cycle 25 (Cdc25) is a key mediator of cell cycle progression that activates cyclin-dependent kinase complexes that drive the cell cycle and participates in the regulation of DNA damage checkpoints. Cdc25B is a member of the Cdc25 family of phosphatases. The present study investigated the role and mechanism of PKCδ in regulating the fertilization of mouse embryos in early development. The expression and subcellular localization of PKCδ and Cdc25B were detected using reverse transcription-quantitative polymerase chain reaction, western blotting and immunofluorescence in one-cell stage mouse embryos. Specific small interfering RNAs targeting PKCδ were used to knockdown the expression of PKCδ. Subsequently, Scansite software was used to predict the target of phosphorylated Cdc25B. Western blotting was used to measure the effects of phosphorylation and dephosphorylation in one-cell stage mouse embryos at different cell cycle phases. PKCδ was expressed during M phase and served a positive role in one-cell stage mouse embryos. Immunofluorescence data revealed that PKCδ and Cdc25B were expressed during G1, S, G2 and M phases of the cell cycle. Furthermore, phosphorylated levels of Cdc25B-Ser96 were observed during G2 and M phases. Microinjection with mimics of phosphorylated Cdc25B-Ser96 mRNA promoted the development of one-cell stage mouse embryos. When PKCδ was suppressed, microinjection with mimics of phosphorylated Cdc25B-Ser96 mRNA reversed the inhibition of PKCδ. To conclude, PKCδ serves a positive role in the first cell cycle of mouse embryos by phosphorylating Cdc25B-Ser96, and provides novel insights for the regulation of early embryonic development.

Interleukin-1 beta induces autophagy of mouse preimplantation embryos and improves blastocyst quality.

Autophagy is one of the basic cellular mechanism during preimplantation development of mammalian embryos, and it plays crucial role in several physiological processes. It is induced by interleukin (IL)-1β in mammalian cells. Our present study shows that IL-1β is important for autophagy activation in embryo development. Our in vitro culture system analysis shows effect of IL-1β in medium on the development of mouse embryos and it was found to be concentration dependent. A preimplantation embryo culture using medium containing IL-1β did not improve cleavage and blastocyst development rates of mouse embryos; however, blastocyst quality was significantly improved by increasing total cell number, especially in supplementary 20 ng/mL IL-1β. Furthermore, autophagy activation mainly occurs in 2 to 4 cell embryo and blastocyst, 20 ng/mL IL-1β into culture medium can effectively enhance levels of messenger RNA and protein of autophagy-related-factors in 2 to 4 cell embryos and blastocyst, while these factors reduce in VGX-1027 (IL-1β inhibitor) groups that also reduce the quality of blastocyst. Effects of IL-1β on the development of embryo reduced in 20 ng/mL IL-1β supplemented group when 5 mM 3-methyladenine (3-MA) was also added, which used to inhibit autophagy activation in endogenous PtdIns3Ks signal pathway. Our current results show that exogenous IL-1β can effectively induce autophagy in mouse embryos at stages of 2 to 8 cell and blastocyst, that also help to improve the quality of blastocyst.

A role for Regulator of G protein Signaling-12 (RGS12) in the balance between myoblast proliferation and differentiation.

Regulators of G Protein Signaling (RGS proteins) inhibit G protein-coupled receptor (GPCR) signaling by accelerating the GTP hydrolysis rate of activated Gα subunits. Some RGS proteins exert additional signal modulatory functions, and RGS12 is one such protein, with five additional, functional domains: a PDZ domain, a phosphotyrosine-binding domain, two Ras-binding domains, and a Gα·GDP-binding GoLoco motif. RGS12 expression is temporospatially regulated in developing mouse embryos, with notable expression in somites and developing skeletal muscle. We therefore examined whether RGS12 is involved in the skeletal muscle myogenic program. In the adult mouse, RGS12 is expressed in the tibialis anterior (TA) muscle, and its expression is increased early after cardiotoxin-induced injury, suggesting a role in muscle regeneration. Consistent with a potential role in coordinating myogenic signals, RGS12 is also expressed in primary myoblasts; as these cells undergo differentiation and fusion into myotubes, RGS12 protein abundance is reduced. Myoblasts isolated from mice lacking Rgs12 expression have an impaired ability to differentiate into myotubes ex vivo, suggesting that RGS12 may play a role as a modulator/switch for differentiation. We also assessed the muscle regenerative capacity of mice conditionally deficient in skeletal muscle Rgs12 expression (via Pax7-driven Cre recombinase expression), following cardiotoxin-induced damage to the TA muscle. Eight days post-damage, mice lacking RGS12 in skeletal muscle had attenuated repair of muscle fibers. However, when mice lacking skeletal muscle expression of Rgs12 were cross-bred with mdx mice (a model of human Duchenne muscular dystrophy), no increase in muscle degeneration was observed over time. These data support the hypothesis that RGS12 plays a role in coordinating signals during the myogenic program in select circumstances, but loss of the protein may be compensated for within model syndromes of prolonged bouts of muscle damage and repair.

Ghrelin deficiency modifies the uterine inflammatory response affecting mice embryo implantation and development.

Ghrelin is a multifunctional gastrointestinal acylated peptide, primarily synthesized in the stomach and regulates the secretion of growth hormone and energy homeostasis. It plays a central role in modulating the diverse biological, physiological and pathological functions in vertebrates. The synthesis of ghrelin receptor ligands after the finding of growth hormone secretagogue developed from Met-enkephalin led to reveal the endogenous ligand ghrelin and the receptors. Subsequently, many peptides, small molecules and peptidomimetics focusing on the ghrelin receptor, GHS-R1a, were derived. In this review, the key features of ghrelin's structure, forms, its bio-physiological functions, pathological roles and therapeutic potential have been highlighted. A few peptidomimetics and pseudo peptide synthetic perspectives have also been discussed to make ghrelin receptor ligands, clinical trials and their success.

2005 - GATA3 PROMOTES THE ENDOTHELIAL-TO-HEMATOPOIETIC TRANSITION VIA REGULATION OF THE CELL CYCLE

Hematopoietic stem cells (HSCs) are known to emerge in the dorsal aorta at E10.5 of mouse embryo development. They derive from hemogenic endothelial cells via a process known as endothelial-to-hematopoietic transition (EHT), which comprises a number of intermediate steps and the molecular details of which have not been fully characterized. Our lab has previously demonstrated that embryos deficient for the transcription factor Gata3 have a defect in HSC generation in the dorsal aorta. This was linked to a lack of catecholamine synthesis in these embryos, which demonstrated that neurotransmitters released from the co-developing sympathetic nervous system promote embryonic HSC production. We now have evidence that Gata3 plays an additional role in EHT. Gata3 expression was found to enrich for hemogenic endothelial cell activity, and an endothelial-specific knockout of Gata3 severely impairs HSC generation in the dorsal aorta. Furthermore, with the use of co-aggregation assays developed in the Medvinsky lab, we were able to determine that Gata3 is expressed in the pro-HSC and pre-HSC type I stage, but is downregulated thereafter. RNA-Seq analysis of Gata3-positive and negative cell populations highlighted a cell cycle signature, with cell cycle inhibitors, such as p57Kip2, specifically enriched in Gata3-expressing cells. This suggests that a cell cycle arrest may be required for endothelial cells to complete the transition to a hematopoietic fate, which is supported by our preliminary results with embryos deficient for p57Kip2. Our results thus provide further insights into the molecular mechanisms of HSC generation from endothelial cells.

Implication of mu opioid receptor in the in vitro maturation of oocytes and its effects on subsequent fertilization and embryo development in mice.

Oocyte maturation is the process by which immature oocytes acquire all the necessary characteristics for successful fertilization. The endogenous opioid peptides have been suggested to have a role modulating this process. However, little is known about its implication and the effect of exposing oocyte maturation to opioids on the subsequent fertilization and embryo development. Hence, in the present work, we focused on elucidating the function of the mu opioid receptor (OPRM1) in the modulation of the oocyte maturation. We analyzed the expression and localization of OPRM1 in mice oocytes and granulosa cells by reverse-transcription polymerase chain reaction (RT-PCR) and immunocytochemistry. To observe the activity of the OPRM1, immature oocytes were incubated with morphine agonist and/or naloxone antagonist and we evaluated the PI3K/Akt and MAPK pathways, as well as the effect on the subsequent fertilization and embryo development. OPRM1 was present in mice oocytes and granulosa cells, changing its expression pattern depending on the maturation stage. Moreover, morphine, modulating PI3K/Akt and MAPK pathways, helped oocytes to reach blastocyst stage, which was reverted by naloxone. These results propose the OPRM1 as a possible therapeutic target for in vitro maturation culture medium, as it could improve the blastocyst rates obtained in the actual reproduction assisted techniques.

Influence of N-acetyl-L-cysteine against bisphenol a on the maturation of mouse oocytes and embryo development: in vitro study

BackgroundBisphenol A (BPA), an endocrine disruptor, is a widely used chemical that has adverse effects on animal development and reproduction. The current research aimed to evaluate the effect of BPA on the in vitro maturation (IVM) and subsequent embryo development of mouse oocytes following in vitro fertilization (IVF).MethodsIVM was performed in the presence of different concentrations (0, 20, 50, or 100 μg/mL) of BPA. Nuclear maturation, IVF efficiency and embryonic development were determined. The levels of reactive oxygen species (ROS) and glutathione (GSH) in the BPA (50 μg/mL) group were evaluated. We explored the ability of N-acetyl-L-cysteine (NAC) in the IVM medium to rescue the BPA-induced damage by examining changes in nuclear maturation, IVF rate, blastocyst formation, ROS levels and GSH content.ResultsCompared with the control, BPA (50 μg/mL) supplementation during oocyte IVM significantly inhibited nuclear maturation and decreased fertilization and blastocyst formation rates. In addition, BPA exposure increased ROS levels and decreased GSH content in oocytes. The addition of NAC weakened the BPA-induced suppression of nuclear maturation, relieved the BPA-induced downregulation of the fertilization and blastocyst formation rates, and mitigated the increased ROS levels and decreased GSH content.ConclusionBPA affects mouse oocyte maturation and subsequent early embryonic developmental competence following IVF by increasing intracytoplasmic oxidative stress in mature oocytes. NAC can reduce these harmful effects to a certain extent.

Development of Textbooks on Animal Embryology and Reproduction Based on Research Results in the Development of Mice Embryos by Adding DEET (Diethyltoluamide)

The purpose of this study was to develop a textbook on Embryology and Animal Reproduction based on the research on the development of mouse embryos by adding DEET (Diethyltoluamide) that was appropriate and validated by material, media and language experts. This research is a development study of textbooks on animal embryology and reproduction based on the results of research on the development of mouse embryos by adding DEET. The development of this textbook refers to the 4D model developed by Thiagarajan, et al. (1974) which consisted of 4 stages, namely Define, Design, Development, and Disseminate, which were modified to be adapted to this study. This development research produced a textbook on Embryology and Animal Reproduction based on research on the development of mouse embryos by adding proper DEET and validating it by material, media and language experts.

Esrrb function is required for proper primordial germ cell development in presomite stage mouse embryos

Estrogen related receptor beta (Esrrb) is an orphan nuclear receptor that is required for self-renewal and pluripotency in mouse embryonic stem (ES) cells. However, in the early post-implantation mouse embryo, Esrrb is specifically expressed in the extraembryonic ectoderm (ExE) and plays a crucial role in trophoblast development. Previous studies showed that Esrrb is also required to maintain trophoblast stem (TS) cells, the in vitro stem cell model of the early trophoblast lineage. In order to identify regulatory targets of Esrrb in vivo, we performed microarray analysis of Esrrb-null versus wild-type post-implantation ExE, and identified 30 genes down-regulated in Esrrb-mutants. Among them is Bmp4, which is produced by the ExE and known to be critical for primordial germ cell (PGC) specification in vivo. We further identified an enhancer region bound by Esrrb at the Bmp4 locus by performing Esrrb ChIP-seq and luciferase reporter assay using TS cells. Finally, we established a knockout mouse line in which the enhancer region was deleted using CRISPR/Cas9 technology. Both Esrrb-null embryos and enhancer knockout embryos expressed lower levels of Bmp4 in the ExE, and had reduced numbers of PGCs. These results suggested that Esrrb functions as an upstream factor of Bmp4 in the ExE, regulating proper PGC development in mice.

Expression of miR-Let-7a, miR-15a, miR-16-1, and their target genes in fresh and vitrified embryos and its surrounding culture media for noninvasive embryo assessment.

microRNAs (miRNAs) play a critical role in implantation and development of mouse embryos. In this study, we aim to evaluate the possibility of miRNAs as potential biomarkers in the blastocyst culture to assess embryo quality. We also intend to investigate whether improved clinical outcomes of vitrified embryos agree with altered miRNA expressions. Mouse embryos from in vitro fertilization were vitrified at the two-cell stage. After thawing, the embryos were individually cultured and developed to the blastocyst stage. We used quantitative real-time polymerase chain reaction to evaluate miRNA expression levels in both vitrified and fresh groups, and culture medium (CM). The fibronectin binding assay was performed to examine for blastocyst attachment. The findings showed reduced expressions of miR-16-1 (0.2 ± 0.06) and miR-Let-7a (0.65 ± 0.1) after vitrification compared to fresh embryos. We observed significant upregulation of the target genes Vav3 (4.33 ± 0.25), integrin β-3 (Itg β3; 4.73 ± 0.2), and Bcl2 (2.29 ± 0.16) in the vitrified embryos compared to the fresh groups. Evaluation of blastocyst CM showed upregulation of miR-Let-7a (15.68 ± 0.89), miR-16-1 (16.18 ± 0.75), and miR-15a (13.36 ± 0.73) in the vitrified group in comparison to the fresh blastocysts (P < .05). The expression levels of miR-16-1 (3.28 ± 0.63), miR-15a (5.91 ± 0.38), and miR-Let-7a (9.07 ± 0.6) in CM of the vitrified blastocysts conducted on fibronectin were significantly higher than the fresh group (P < .05).This study showed that vitrification of embryos changes implantation and proliferation biomarkers. In addition, upregulated miRNAs in CM could be potentially used for noninvasive early assessment of embryo quality.

Compression Generated by a 3D Supracellular Actomyosin Cortex Promotes Embryonic Stem Cell Colony Growth and Expression of Nanog and Oct4.

Mechanical factors play critical roles in mammalian development. Here, we report that colony-growing mouse embryonic stem cells (mESCs) generate significant tension on the colony surface through the contraction of a three-dimensional supracellular actomyosin cortex (3D-SAC). Disruption of the 3D-SAC, whose organization is dependent on the Rho/Rho-associated kinase (ROCK) signals and E-cadherin, results in mESC colony destruction. Reciprocally, compression force, which is generated by the 3D-SAC, promotes colony growth and expression of Nanog and Oct4 in mESCs and blastocyst development of mouse embryos. These findings suggest that autonomous cell forces regulate embryonic stem cells fate determination and provide insight regarding the biomechanical regulation of embryonic development.

The role of Kifc1, Kchn5 and miRNA-302 on in vitro development in 8-cell, morula and blastocyst stage of mouse embryos

Introduction: Embryo development is characterized by lack of cell cycle check-points and overexpression of core circadian oscillators. On previous report we have identified several genes over-and under-detected at human embryo blastomeres. In this study, we investigated the expression profile of Kcnh5, KIFC1 and miRNA-302 genes at three pre-implantation stages of mouse embryo development. Material and methods: Total RNA was extracted from mouse embyos at 8-cell, morula and blastocyst stage. The expression profile of Kcnh5, KIFC1 and miRNA-302 was assessed by RT-PCR and the results were normalized with G6pdh expression levels. Results: Kcnh5 showed absence of expression at all stages, indicating novel mechanisms of cell cycle control during blastomeres divisions. KIFC1 showed positive expression at all stages, with decreasing levels as the embryogenesis progresses. This finding indicates that KIFC1 may have more important role at early events. miRNA-302 showed increased levels of expression at all stages, with morula having the highest levels. Therefore, miRNA-302 might play an important role at the events that happen during morula stage such as compaction. Conclusions: Cell cycle control of blastomeres at early embryogenesis might be based on different mechanisms compared to somatic cells and more research is needed in order to reveal crucial cycling elements.