Delays in the final stages of fertilization are strongly associated with trichotomous cytokinesis and cleavage arrest.

Purpose: Recent evidence showed that the phase between pronuclear fading and the first cleavage is a perilous bridge connecting the zygote and the embryo. Indeed, delay in the short interval between pronuclear breakdown (PNBD) and the first cytokinesis may result in chromosome segregation errors. We tested the hypothesis that delays in this final phase of fertilization are associated with a detrimental impact on embryo development.

Towards a more sustainable balance between optimal live birth rate and supernumerary embryos in ART treatments.

Purpose: To assess the relation between number of inseminated oocytes and cumulative live birth rate (CLBR) in order to provide guidance for limiting the number of surplus blastocysts.

Methods: The study was a retrospective, single-center cohort analysis of 1223 ART complete cycles. Cycles were stratified according to female age (≤ 34, 35-38, and 39-42 years) and number of inseminated oocytes (1-5, 6-10, and > 10).

The destinies of human embryos reaching blastocyst stage between Day 4 and Day 7 diverge as early as fertilization.

Study Question: What clinical and laboratory differences emerge from parallel direct comparison of embryos reaching the blastocyst stage between Days 4, 5, 6, and 7 (Days 4-7)?

Summary Answer: Increasing times to blastocyst formation are associated with a worse clinical outcome and perturbations in developmental patterns appear as early as the fertilization stage.

What Is Known Already: Previous evidence indicates that later times to blastocyst development are associated with a worse clinical outcome. However, the vast majority of these data concern Day 5 and Day 6 blastocysts, while Day 4 and Day 7 blastocysts remain less thoroughly investigated.

Fine-tuning IVF laboratory key performance indicators of the Vienna consensus according to female age.

Purpose: To test the validity of the Vienna consensus laboratory key performance indicators (KPIs) to monitor the outcome of treatments involving women of different age ranges.

Methods: The retrospective cohort study included 862 complete IVF/ICSI cycles carried out between January 2014 and May 2021. All embryos of each cycle cohort were subject to extended culture.

The Association of Kinetic Variables with Blastocyst Development and Ploidy Status.

Background: Despite a plethora of studies conducted so far, a debate is still unresolved as to whether TLM can identify predictive kinetic biomarkers or algorithms universally applicable. Therefore, this study aimed to elucidate if there is a relationship between kinetic variables and ploidy status of human embryos or blastocyst developmental potential.

Methods: For conducting this retrospective cohort study, the normal distribution of data was verified using Kolmogorov-Smirnov test with the Lilliefors' amendment and the Shapiro-Wilk test.

The paternal toolbox for embryo development and health.

The sperm is essential for reconstitution of embryonic diploidy and highly specialized developmental functions. Immediately after gamete fusion, the sperm-borne PLC-zeta triggers activation, generating intracellular free Ca2+ oscillations. Mutations in the PLC-zeta encoding gene are associated with the absence of this factor in mature sperm and inability to achieve fertilization.

Plasticity of the human preimplantation embryo: developmental dogmas, variations on themes and self-correction.

Background: IVF for the treatment of infertility offers unique opportunities to observe human preimplantation development. Progress in time-lapse technology (TLT) and preimplantation genetic testing (PGT) has greatly expanded our knowledge of developmental patterns leading to a healthy pregnancy or developmental failure. These technologies have also revealed unsuspected plastic properties of the preimplantation embryo, at macromolecular, cellular and multicellular levels.

Perturbations of morphogenesis at the compaction stage affect blastocyst implantation and live birth rates.

Study Question: Do perturbations of embryo morphogenesis at compaction affect blastocyst development and clinical outcomes in assisted reproduction cycles?

Summary Answer: Cell exclusion and extrusion, i.e. cell disposal occurring respectively before or during morula compaction, affect blastocyst yield and quality, as well as rates of pregnancy and live birth.

Sperm count affects cumulative birth rate of assisted reproduction cycles in relation to ovarian response.

Purpose: To explore the possible influence of sperm quality, as assessed by prewash total sperm count (TSC), on cumulative success rates in assisted reproduction cycles.

Methods: Retrospective study carried out in private IVF centre. Seven hundred sixty-five couples undergoing complete ICSI cycles, i.

Male factor infertility impacts the rate of mosaic blastocysts in cycles of preimplantation genetic testing for aneuploidy.

Purpose: In this study, we tested the hypothesis that, in PGT-A cycles, decreased semen quality is associated with increased rates of mosaic blastocysts.

Methods: In a retrospective analysis, three hundred and forty PGT-A cycles are divided into study groups according to semen quality. Cycles were initially divided into two groups, discerning couples with absence of male factor of infertility (non-male factor: NMF; N = 146 cycles) from couples with a male factor of infertility (MF; N = 173 cycles).

The enigmatic morula: mechanisms of development, cell fate determination, self-correction and implications for ART.

Background: Assisted reproduction technology offers the opportunity to observe the very early stages of human development. However, due to practical constraints, for decades morphological examination of embryo development has been undertaken at a few isolated time points at the stages of fertilisation (Day 1), cleavage (Day 2-3) and blastocyst (Day 5-6). Rather surprisingly, the morula stage (Day 3-4) has been so far neglected, despite its involvement in crucial cellular processes and developmental decisions.

Embryo morphokinetic characteristics and euploidy.

Purpose Of Review: The purpose of the current review is to provide an update on time-lapse morphokinetic assessment related to embryo ploidy status.

Recent Findings: The main limitation of the available studies regarding correlation between morphokinetic variables and ploidy is that each embryo is considered as an independent unit whereas recent findings show that embryo kinetics may be affected by patient and ovarian stimulation-related factors, so that clustered data analysis is more appropriate. Moreover, some experimental evidences show how embryos with irregular developmental patterns, often used as deselection criteria, can evolve into usable embryos and give pregnancy.

A quantitative approach to blastocyst quality evaluation: morphometric analysis and related IVF outcomes.

Purpose: To quantify blastocyst morphologic parameters with a feasible and standardized tool, investigating their predictive value on implantation outcome.

Method: The study retrospectively analyzes 124 blastocysts from 75 patients. Quantitative measurements of blastocyst expansion, inner cell mass and trophoectoderm were taken using digital image analysis software.

Cumulative pregnancy rates resulting from the use of fresh and frozen oocytes: 7 years' experience.

Storing supernumerary embryos and transferring them later fully utilizes the reproductive potential of retrieved oocytes, allowing a significant increase in the overall number of pregnancies achieved from a single cycle of ovarian stimulation treatment. As an alternative to embryo cryopreservation, preservation of unfertilized oocytes has been proposed to maximize clinical outcome. This paper presents data concerning the cumulative pregnancy rate after use of fresh and cryopreserved oocytes.

Predictive factors for embryo implantation potential.

In spite of recent improvements in IVF, pregnancy rates have not increased significantly and one of the major problems remains the high multiple pregnancy rate. Better criteria are therefore necessary to establish the viability of a transferable embryo. Early prognosis of the developmental fate of the oocyte would help in selecting the best embryos to transfer, but non-invasive selection at the oocyte stage (extracytoplasmic and intracytoplasmic morphology) has proved to be of little prognostic value.

Artificial reproductive technology achievements for optimizing embryo quality.

Evaluation of morphological characteristics, to date, has been the most widely accepted method for the selection of embryos with higher developmental ability and optimization of the outcome of in vitro fertilization (IVF). Improvement in clinical results has also been pursued through attempts to generate embryos of high quality or to identify more reliable selection criteria. This work evaluates the possibility of improving embryo quality and subsequent IVF outcome in situations in which creation of supernumerary embryos is not allowed.