1
|
Ezoe K, Takahashi T, Miki T, Kato K. Developmental perturbation in human embryos: Clinical and biological significance learned from time-lapse images. Reprod Med Biol 2024; 23:e12593. [PMID: 38983691 PMCID: PMC11232294 DOI: 10.1002/rmb2.12593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 05/30/2024] [Accepted: 06/07/2024] [Indexed: 07/11/2024] Open
Abstract
Background Time-lapse technology (TLT) has gained widespread adoption worldwide. In addition to facilitating the undisturbed culture of embryos, TLT offers the unique capability of continuously monitoring embryos to detect spatiotemporal changes. Although these observed phenomena play a role in optimal embryo selection/deselection, the clinical advantages of introducing TLT remain unclear. However, manual annotation of embryo perturbation could facilitate a comprehensive assessment of developmental competence. This process requires a thorough understanding of embryo observation and the biological significance associated with developmental dogma and variation. This review elucidates the typical behavior and variation of each phenomenon, exploring their clinical significance and research perspectives. Methods The MEDLINE database was searched using PubMed for peer-reviewed English-language original articles concerning human embryo development. Main findings TLT allows the observation of consecutive changes in embryo morphology, serving as potential biomarkers for embryo assessment. In assisted reproductive technology laboratories, several phenomena have not revealed their mechanism, posing difficulties such as fertilization deficiency and morula arrest. Conclusion A profound understanding of the biological mechanisms and significance of each phenomenon is crucial. Further collaborative efforts between the clinical and molecular fields following translational studies are required to advance embryonic outcomes and assessment.
Collapse
|
2
|
Inoue T, Taguchi S, Uemura M, Tsujimoto Y, Kokunai K, Ikawa K, Yamashita Y. The migration speed of nucleolar precursor bodies in pronuclei affects in vitro fertilization-derived human embryo ploidy status and live birth. Reprod Med Biol 2023; 22:e12497. [PMID: 36699958 PMCID: PMC9853468 DOI: 10.1002/rmb2.12497] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 12/04/2022] [Accepted: 12/21/2022] [Indexed: 01/22/2023] Open
Abstract
Purpose To study the relationship between clinical outcomes after assisted reproduction and the migration speed of nucleolus precursor bodies (NPBs) in male and female pronuclei (mPN; fPN). Methods NPB migration speed, embryo ploidy status, and live birth (LB) were retrospectively analyzed in IVF-derived zygotes. The central coordinates of the mPN, fPN, and NPBs were noted at multiple timepoints. The migration distance of NPBs between two sequential images was measured to calculate NPB migration speed. Results The NPB migration speeds in mPN and fPN were significantly faster in euploid zygotes than in aneuploid zygotes. In multivariate logistic analysis, NPB migration speed in mPN and the female age were associated with euploidy. The NPB migration speeds in mPN and fPN were also significantly faster in zygotes that led to LB than in zygotes that led to no pregnancy. In a receiver operating characteristic curve analysis of LB by NPB migration speed in mPN, the cut-off value was 3.74 μm/h (AUC: 0.825, 95%CI: 0.688-0.963). When the zygotes were categorized by this cut-off value, there were significantly more LBs in zygotes with migration speed ≥ the cut-off (78.9% vs. 21.1%). Conclusions Zygotes with quickly migrating NPBs demonstrated the developmental potential to become a baby.
Collapse
Affiliation(s)
- Taketo Inoue
- Umeda Fertility ClinicOsakaJapan
- Department of Emergency, Disaster and Critical Care MedicineHyogo Medical UniversityNishinomiyaJapan
| | | | - Mikiko Uemura
- Department of Rehabilitation, Faculty of Health ScienceKansai University of Welfare SciencesOsakaJapan
| | | | | | | | | |
Collapse
|
3
|
Bari MW, Morishita Y, Kishigami S. Heterogeneity of nucleolar morphology in four-cell mouse embryos after IVF: association with developmental potential. Anim Sci J 2023; 94:e13907. [PMID: 38102887 DOI: 10.1111/asj.13907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 11/22/2023] [Accepted: 11/27/2023] [Indexed: 12/17/2023]
Abstract
In mammals, around fertilization, the nucleolus of embryos transforms into the nucleolus precursor bodies (NPBs), which continue to mature until the blastocyst stage, leading to distinct morphological changes. In our study, we observed two types of nucleolar morphology in mouse in vitro fertilized embryos at the four-cell stage, which we refer to single nucleolus (SN) and multiple nucleoli (MN). To visualize nucleolar morphology, four-cell embryos were immunostained with anti-NOPP140 antibody. These embryos were categorized into five types based on the number of blastomeres carrying SN: SN4/MN0, SN3/MN1, SN2/MN2, SN1/MN3, and SN0/MN4, with percentages of 13, 27, 21, 23 and 9, respectively. Next, using a light microscope, we divided the four-cell in vitro fertilized embryos without fixation into two groups: those with at least two blastomeres displaying SN (SN embryos) and those without (MN embryos). Notably, significantly more SN embryos developed into blastocysts and offspring at 18.5 dpc compared with MN embryos. Furthermore, SN embryos displayed a higher NANOG-positive cell number at the blastocyst stage, significantly lower body and placental weights, resulting in a higher fetal/placental ratio. These findings suggest a close association between nucleolar state at the four-cell stage and subsequent developmental potential.
Collapse
Affiliation(s)
- Md Wasim Bari
- Department of Integrated Applied Life Science, Integrated Graduate School of Medicine, Engineering, and Agricultural Sciences, University of Yamanashi, Kofu, Japan
| | - Yoshiya Morishita
- Graduate School of Life and Environmental Sciences, Integrated Graduate School of Medicine, Engineering, and Agricultural Sciences, University of Yamanashi Kofu, Japan
| | - Satoshi Kishigami
- Department of Integrated Applied Life Science, Integrated Graduate School of Medicine, Engineering, and Agricultural Sciences, University of Yamanashi, Kofu, Japan
- Graduate School of Life and Environmental Sciences, Integrated Graduate School of Medicine, Engineering, and Agricultural Sciences, University of Yamanashi Kofu, Japan
- Center for advanced Assisted Reproductive Technologies, University of Yamanashi, Kofu, Japan
| |
Collapse
|
4
|
Park JK, Ahn SY, Seok SH, Park SY, Bang S, Eum JH, Kwak IP, Kim JW, Lee WS. Clinical Usability of Embryo Development Using a Combined Qualitative and Quantitative Approach in a Single Vitrified-Warmed Blastocyst Transfer: Assessment of Pre-Vitrified Blastocyst Diameter and Post-Warmed Blastocyst Re-Expansion Speed. J Clin Med 2022; 11:jcm11237085. [PMID: 36498659 PMCID: PMC9736480 DOI: 10.3390/jcm11237085] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/08/2022] [Accepted: 11/25/2022] [Indexed: 12/04/2022] Open
Abstract
Improving the safety and efficacy of assisted reproductive technology programs has been a continuous challenge. Traditionally, morphological grading has been used for embryo selection. However, only a few studies have assessed the morphokinetic variables and morphological dynamics of blastocysts. In the present study, we aimed to perform a quantitative analysis of blastocyst diameter and re-expansion speed. This in-depth morphokinetic evaluation can correlate with currently observed pregnancy outcomes. In total, 658 single vitrified-warmed blastocyst transfer cycles were performed between October 2017 and December 2021, which were divided into four groups according to the pre-vitrified blastocyst diameter. After warming, the groups were subdivided according to the blastocyst re-expansion speed. These quantitative measurements were performed using a time-lapse system. Both diameter and speed are essential in determining the blastocyst quality, while age, day of freezing, and blastocyst quality are crucial from a clinical perspective. The application of both quantitative (diameter and speed) and qualitative (blastocyst quality scores) parameters can help evaluate the clinical usability of blastocysts. This method can prove useful for embryologists in counseling their patients and determining pregnancy patient-oriented strategies.
Collapse
|
5
|
Ezoe K, Takahashi T, Shimazaki K, Miki T, Tanimura Y, Amagai A, Sawado A, Akaike H, Mogi M, Kaneko S, Kato M, Kato K, Tarozzi N, Borini A, Coticchio G. Human 1PN and 3PN zygotes recapitulate all morphokinetic events of normal fertilization but reveal novel developmental errors. Hum Reprod 2022; 37:2307-2319. [PMID: 35950593 DOI: 10.1093/humrep/deac177] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 07/20/2022] [Indexed: 11/13/2022] Open
Abstract
STUDY QUESTION Does mono- (1PN) and tri-pronuclear (3PN) fertilization recapitulate the morphokinetic changes of normal bi-pronuclear (2PN) fertilization? SUMMARY ANSWER Abnormal fertilization retraces the overall choreography of normal fertilization but reveals novel morphokinetic phenomena and raises scientifically and clinically relevant questions. WHAT IS KNOWN ALREADY ART has allowed the extracorporeal observation of early human development. Time-lapse technology (TLT) has revealed the complexity of the morphokinetic changes underpinning fertilization and the importance of this process for the genetic and cellular integrity of the embryo. Abnormal fertilization has remained neglected, despite its relevance to the physiology and pathology of early human development. STUDY DESIGN, SIZE, DURATION This retrospective study involved TLT observation of normally (2PN, N = 2517) and abnormally (1PN, N = 41; 3PN, N = 27) fertilized oocytes generated in ICSI cycles performed between October 2019 and December 2020. Oocyte retrieval was carried out after clomiphene citrate-based minimal ovarian stimulation. Oocytes of patients with different diagnoses of infertility were included in the analysis, while cases involving cryopreserved gametes or surgically retrieved sperm were excluded. PARTICIPANTS/MATERIALS, SETTING, METHODS The study included 1231 couples treated for diverse infertility causes. The fraction of male factor cases was substantial (36.1%). Microinjected oocytes were assessed by a combined TLT-culture system. Oocytes not suitable for TLT assessment, owing to an excess of residual corona cells or inadequate orientation for correct observation, were not analysed. Phenomena relevant to meiotic resumption, pronuclear dynamics, cytoplasmic/cortical modifications, cleavage patterns and embryo quality were annotated and compared between groups. MAIN RESULTS AND THE ROLE OF CHANCE Extrusion of the second polar body (PBII) was observed in almost all 2PN/1PN (99.9% and 100.0%, respectively) and in a vast majority of 3PN zygotes (92.1%). Rates of PBII fusion with the ooplasm were much higher in 1PN and 3PN zygotes (P < 0.0001 versus 2PN). The cytoplasmic wave was observed not only in 2PN and 3PN but also in 1PN zygotes (positivity rates of 99.8% and 100% and 82.9%, respectively; P < 0.0001). More rarely, 2PN and 1PN zygotes emitted a third polar body (PBIII). The average times of this event were comparable. The presence and position of the cytoplasmic halo were comparable among the three classes of zygotes. In the 1PN group, the single PN was maternally or paternally derived in 17 and 24 zygotes, respectively, while in the vast majority of 3PN zygotes (121/127) the supernumerary PN was of maternal origin. Average times of maternal PN appearance were comparable, while average times of paternal PN appearance were delayed in 3PN zygotes (P = 0.0127). Compared with the control group, the area of the maternal PN was larger in 1PN zygotes, but smaller in 3PN zygotes (P < 0.0001). The paternal PNs displayed the same trend (P < 0.0001), although such values were consistently smaller than maternal PNs. The area of the third PN in the 3PN group was on average more than 50% smaller than those of maternal and paternal PNs. In maternal PNs of 3PN zygotes, nucleolus precursor bodies (NPBs) aligned along the area of PN juxtaposition at a lower rate compared with the 2PN group. The rate of NPB alignment was ∼50% smaller in 1PN zygotes (P = 0.0001). In paternal PNs, the rates of NPB alignment were not statistically different among the three groups. Asynchronous PN breakdown was increased in 3PN compared with 2PN zygotes (P = 0.0026). In 1PN zygotes, a developmental delay was observed starting from the disappearance of the cytoplasmic halo, reaching 9 h at the time of the first cleavage (P < 0.0001). Higher rates of abnormal cleavage patterns and blastomere fragmentation (P < 0.0001) were observed in 1PN compared to 2N and 3PN zygotes. Cleavage progression was increasingly affected after abnormal fertilization, especially 1PN, finally resulting in blastocyst formation rates of 70.2%, 12.2% and 53.5% in 2PN, 1PN and 3PN embryos, respectively (P < 0.0001). Both maternal and paternal ages were higher in cases involving 3PN fertilization. LIMITATIONS, REASONS FOR CAUTION The study data were obtained from ICSI, but not standard IVF, treatments carried out in a single centre. The study findings therefore require independent verification. WIDER IMPLICATIONS OF THE FINDINGS This study reports the first detailed morphokinetic map of human abnormal fertilization. Collectively, this evidence prompts new scientific hypotheses and raises clinical questions relevant to the aetiology and the treatment of abnormal fertilization. STUDY FUNDING/COMPETING INTEREST(S) This study was supported by the participating institutions. The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER N/A.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - Mai Mogi
- Kato Ladies Clinic, Tokyo, Japan
| | | | | | | | | | | | | |
Collapse
|
6
|
Coticchio G, Borini A, Zacà C, Makrakis E, Sfontouris I. Fertilization signatures as biomarkers of embryo quality. Hum Reprod 2022; 37:1704-1711. [PMID: 35640036 DOI: 10.1093/humrep/deac123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 05/11/2022] [Indexed: 12/29/2022] Open
Abstract
Fertilization underpins the vital transition from gametic meiosis to embryonic mitosis. For decades, in human IVF, microscopic observation at a single time point has limited our appreciation of the morphokinetic complexity of this process. More recently, the introduction of time lapse technology-also enhanced by combination with artificial intelligence-has revealed the finest morphokinetic details of the beginning of human development. Overall, a picture has finally emerged in which the precise timing, morphology and geometry of several fertilization events offer clues to predict the fate of the embryo-a key aspect of assisted reproduction. In this scenario, correct unfolding of intra- and interpronuclear rearrangements emerge as a crucial factor to create a platform able to preserve genetic and cellular integrity at the first mitotic cleavage.
Collapse
|
7
|
OUP accepted manuscript. Hum Reprod 2022; 37:1148-1160. [DOI: 10.1093/humrep/deac066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/22/2022] [Indexed: 11/14/2022] Open
|
8
|
Orevich LS, Watson K, Ong K, Korman I, Turner R, Shaker D, Liu Y. Morphometric and morphokinetic differences in the sperm- and oocyte-originated pronuclei of male and female human zygotes: a time-lapse study. J Assist Reprod Genet 2022; 39:97-106. [PMID: 34993708 PMCID: PMC8866592 DOI: 10.1007/s10815-021-02366-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 11/23/2021] [Indexed: 01/03/2023] Open
Abstract
PURPOSE To study the morphometric and morphokinetic profiles of pronuclei (PN) between male and female human zygotes. METHOD(S) This retrospective cohort study included 94 consecutive autologous single day 5 transfer cycles leading to a singleton live birth. All oocytes were placed in the EmbryoScope + incubator post-sperm injection with all annotations performed retrospectively by one embryologist (L-SO). Timing parameters included 2nd polar body extrusion (tPB2), sperm-originated PN (tSPNa) or oocyte-originated PN (tOPNa) appearance, and PN fading (tPNF). Morphometrics were evaluated at 8 (stage 1), 4 (stage 2), and 0 h before PNF (stage 3), measuring PN area (um2), PN juxtaposition, and nucleolar precursor bodies (NPB) arrangement. RESULTS Male zygotes had longer time intervals of tPB2_tSPNa than female zygotes (4.8 ± 0.2 vs 4.2 ± 0.1 h, OR = 1.442, 95% CI 1.009-2.061, p = 0.044). SPN increased in size from stage 1 through 2 to 3 (435.3 ± 7.2, 506.7 ± 8.0, and 556.3 ± 8.9 um2, p = 0.000) and OPN did similarly (399.0 ± 6.1, 464.3 ± 6.7, and 513.8 ± 6.5 um2, p = 0.000), with SPN being significantly larger than OPN at each stage (p < 0.05 respectively). More male than female zygotes reached central PN juxtaposition at stage 1 (76.7% vs 51.0%, p = 0.010), stage 2 (97.7% vs 86.3%, p = 0.048), and stage 3 (97.7% vs 86.3%, p = 0.048). More OPN showed aligned NPBs than in SPN at stage 1 only (44.7% vs 28.7%, p = 0.023). CONCLUSION(S) Embryos with different sexes display different morphokinetic and morphometric features at the zygotic stage. Embryo selection using such parameters may lead to unbalanced sex ratio in resulting offspring.
Collapse
Affiliation(s)
| | - Kate Watson
- Monash IVF Gold Coast, 2 Short Street, Southport, QLD L34215 Australia
| | - Kee Ong
- Monash IVF Gold Coast, 2 Short Street, Southport, QLD L34215 Australia
| | - Irving Korman
- Monash IVF Gold Coast, 2 Short Street, Southport, QLD L34215 Australia
| | - Ross Turner
- Monash IVF Auchenflower, Auchenflower, QLD Australia
| | - David Shaker
- Monash IVF Rockhampton, Rockhampton, QLD Australia ,Rural Clinical School, University of Queensland, Brisbane, QLD Australia
| | - Yanhe Liu
- Monash IVF Gold Coast, 2 Short Street, Southport, QLD L34215 Australia ,Monash IVF Auchenflower, Auchenflower, QLD Australia ,Monash IVF Rockhampton, Rockhampton, QLD Australia ,School of Human Sciences, University of Western Australia, Crawley, WA Australia ,School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA Australia ,School of Health Sciences and Medicine, Bond University, Robina, QLD Australia
| |
Collapse
|
9
|
FULKA H, LOI P, PALAZZESE L, BENC M, FULKA, Jr. J. Nucleus reprogramming/remodeling through selective enucleation (SE) of immature oocytes and zygotes: a nucleolus point of view. J Reprod Dev 2022; 68:165-172. [PMID: 35431279 PMCID: PMC9184824 DOI: 10.1262/jrd.2022-004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It is now approximately 25 years since the sheep Dolly, the first cloned mammal where the somatic cell nucleus from an adult donor was used for transfer, was born. So far, somatic cell
nucleus transfer, where G1-phase nuclei are transferred into cytoplasts obtained by enucleation of mature metaphase II (MII) oocytes followed by the activation of the reconstructed cells, is
the most efficient approach to reprogram/remodel the differentiated nucleus. In general, in an enucleated oocyte (cytoplast), the nuclear envelope (NE, membrane) of an injected somatic cell
nucleus breaks down and chromosomes condense. This condensation phase is followed, after subsequent activation, by chromatin decondensation and formation of a pseudo-pronucleus (i) whose
morphology should resemble the natural postfertilization pronuclei (PNs). Thus, the volume of the transferred nuclei increases considerably by incorporating the content released from the
germinal vesicles (GVs). In parallel, the transferred nucleus genes must be reset and function similarly as the relevant genes in normal embryo reprogramming. This, among others, covers the
relevant epigenetic modifications and the appropriate organization of chromatin in pseudo-pronuclei. While reprogramming in SCNT is often discussed, the remodeling of transferred nuclei is
much less studied, particularly in the context of the developmental potential of SCNT embryos. It is now evident that correct reprogramming mirrors appropriate remodeling. At the same time,
it is widely accepted that the process of rebuilding the nucleus following SCNT is instrumental to the overall success of this procedure. Thus, in our contribution, we will mostly focus on
the remodeling of transferred nuclei. In particular, we discuss the oocyte organelles that are essential for the development of SCNT embryos.
Collapse
Affiliation(s)
- Helena FULKA
- Institute of Experimental Medicine, Prague, Czech Republic
| | - Pasqualino LOI
- Faculty of Veterinary Medicine, University of Teramo, Teramo, Italy
| | - Luca PALAZZESE
- Institute of Genetics and Animal Biotechnology of the Polish Academy of Sciences, 05-552 Jastrzebiec, Poland
| | - Michal BENC
- Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, Slovak Republic
| | | |
Collapse
|
10
|
The slippery slope antedating syngamy: pronuclear activity in preparation for the first cleavage. J Assist Reprod Genet 2021; 38:1721-1723. [PMID: 34052999 DOI: 10.1007/s10815-021-02238-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 05/17/2021] [Indexed: 10/20/2022] Open
Abstract
Nucleolus precursor bodies (NPB) are aggregations of intrapronuclear material observed in the pronuclei of fertilized human eggs. They derive from and evolve into nucleoli of the growing oocyte and the early embryo, respectively. Decades-old observations suggest that the patterns of their distribution represent a morphological marker of embryo developmental competence. Recent time-lapse microscopy (TLM) data now indicate that the vectorial characteristics of NPB movement can predict blastocyst formation, euploidy, and implantation. Since distributions of NPB and chromatin coincide, chromatin rearrangement in preparation for the first mitotic cleavage is emerging as a crucial process of early development.
Collapse
|