Embryo Kinetics and Aneuploidy
Carlos Simón, Carmen Rubio in Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
In this chapter we are going to summarize the most important studies related to the importance of morphokinetics in the in vitro fertilization laboratory. First, we are going to look at the evolution of embryo selection techniques with their advantages and disadvantages. Second, we will describe the importance of morphokinetic parameters and predictive algorithms in the improvement of reproductive outcomes. Next, we will define aneuploidy and explain the techniques available to detect aneuploidies and the importance of diagnosis. Subsequently, we will debate the most relevant morphokinetic parameters and algorithms capable of predicting the embryo's ploidy. Finally, we describe the limitations that prevent patients from accessing the technique and the future perspectives in the field of morphokinetics.
Gene Control In Embryonic Development
David S. Latchman in Gene Control, 2020
This chapter discusses the regulation of gene transcription by specific transcription factors plays a key role in this process. A number of these transcription factors are expressed at specific times and places during embryonic development and play a central role in this process. Interestingly in the zebrafish embryo, which provides a vertebrate example of this process, the TATA-binding protein component of the TFIID complex has been shown to be critical for the switching on of transcription from the embryonic genome. The combination of the increasing transcription of the embryonic genome and the progressive degradation of maternal messenger RNAs results in a progressive transition from the maternal to the embryo genome as the embryo develops through the blastula and gastrula stages. During subsequent embryonic development, the Inner cell mass cells are able to give rise to all the different cell types in the early embryo including derivatives of all three germ layers of the embryo, ectoderm, mesoderm, and endoderm.
Embryo Cell-Free DNA in the Culture Medium and Its Potential for Non-Invasive Aneuploidy Testing
Carlos Simón, Carmen Rubio in Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Aneuploidy is common in preimplantation human embryos. Because abnormal chromosome number can negatively affect reproductive outcomes, embryos are routinely tested for aneuploidy before being transferred into the uterus during in vitro fertilization, typically via a trophectoderm biopsy at the blastocyst stage. However, the recent discovery that embryos secrete cell-free DNA into the culture medium during in vitro development opens the possibility of an alternative, non-invasive assay. Embryonic cell-free DNA-based assays show high concordance with trophectoderm biopsies, with the inner cell mass and with the whole blastocyst. Informativity and concordance rates may be influenced by the day of media collection, the volume of the culture drop, the presence of DNA from cumulus cells, and previous manipulation of the embryos. In this chapter, we outline the clinical application of embryonic cell-free DNA analysis as a biomarker to prioritize blastocysts for transfer, with the aim of increasing implantation rates, decreasing miscarriage rates, and shortening the time to pregnancy. We also discuss ongoing research on the mechanisms underlying embryonic cell-free DNA secretion.
How do laboratory embryo transfer techniques affect IVF outcomes? A review of current literature
Published in Human Fertility, 2017
George Sigalos, Olga Triantafyllidou, Nikos Vlahos
Over the last few years, many studies have focused on embryo selection methods, whereas little attention has been given to the standardization of the procedure of embryo transfer. In this review, several parameters of the embryo transfer procedure are examined, such as the: (i) culture medium volume and loading technique; (ii) syringe and catheters used for embryo transfer; (iii) viscosity and composition of the embryo transfer medium; (iv) environment of embryo culture; (v) timing of embryo transfer; (vi) and standardization of the embryo transfer techniques. The aim of this manuscript is to review these factors and compare the existing embryo transfer techniques and highlight the need for better embryo transfer standardization.
Phenotypic plasticity of aposporous embryo sac development in
Published in Plant Signaling & Behavior, 2019
Martina Juranić, Susan D. Johnson, Anna M. Koltunow
ABSTRACT Apomixis in Hieracium praealtum follows a developmental pathway of apospory, where an unreduced embryo sac develops from a somatic ovule cell without meiosis. The avoidance of meiosis together with fertilization-independent seed formation leads to clonal progeny genetically identical to the maternal plant. We have previously described the initial developmental steps of aposporous embryo sac formation in H. praealtum and here, we cytologically observed more than 500 ovules with a focus on the later stages of embryo sac maturation. Aposporous embryo sac maturation is a stochastic process in H. praealtum with single or multiple embryo sacs formed, in addition to off-types and embryo sac abortion. The frequency of twin embryo sacs growing at the same rate is a rare event and, in most ovules, the additional embryo sac undergoes developmental arrest suggesting dominance or growth promotion of a single embryo sac. Observed deviations from the Polygonum-type embryo sac in H. praealtum indicate developmental plasticity during embryo sac maturation. Nevertheless, fertilization-independent seed formation successfully occurs.
Single embryo transfer improve the perinatal outcome in singleton pregnancy
Published in The Journal of Maternal-Fetal & Neonatal Medicine, 2020
Yu Wu, Wei Chen, Lina Zhou, Xiaohong Gao, Xiaowei Xi
Background and objectives: Most of previous studies are comparing the perinatal outcome on singleton babies. There has been no study evaluating the possible effect of singleton embryo transfer on the perinatal outcomes in initial singleton pregnancy resulting from fresh embryo transfer. The purpose of our study is to access the effect of embryo transfer number on obstetric and perinatal risks in order to examine the role of single embryo transfer on perinatal outcomes on initial singleton pregnancy. Materials and methods: This study is a retrospective cohort study and analyzed 6439 fresh embryo transfer women. 1647 initial singleton pregnancy patients were divided into one of the following three groups according to the embryo transfer number: group A (n = 94): single embryo transfer (SET); group B (n = 1321): double embryo transfer (DET); group C (n = 262): triple embryo transfer (TET). The miscarriage rate and the ectopic pregnancy rate was compared between group A and group B, group C. 1273 live birth patients were divided into three groups too. The obstetrics outcomes and perinatal outcomes between group A and group B, group C. Results: There were 94 singleton pregnancy patients in unselective single embryo transfer. Comparing with double embryo transfer, the early miscarriage rate was higher, but late miscarriage rate, ectopic rate, and live birth rate were comparable between two groups. The obstetrics outcomes were comparable between single embryo transfer and other two groups. Although there was no significant difference between group A and other two groups, preterm birth rate, extremely preterm birth rate, low-birth weight rate and very low-birth weight rate increased with the increase of embryo transfer number. The mean delivery weight was highest in singleton babies in single embryo transfer group. It is higher in group A comparing with group B (3440.4 versus 3320.7 g) and comparing with group C (3440.4 versus 3277.4 g). Conclusions: Single embryo transfer was associated with a better perinatal outcome such as preterm birth and low-birth weight in a singleton pregnancy. The mean birth weight was significantly higher in single embryo transfer group too. Single embryo transfer is a reasonable option to reach the goal of in vitro-fertilization – a healthy singleton neonate.
Related Knowledge Centers
- Cell Division
- Ploidy
- Developmental Biology