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Objections to the Basic Moral Status of Human Embryos
Published in Christopher Kaczor, The Ethics of Abortion, 2023
Some people have noted that the embryo does indeed have directedness toward human maturity, but the object that the embryo lacks inner directedness characteristic of an organism. The embryo's developmental trajectory is governed by maternal RNA, not by the embryo's own genetic endowment. In the words of Stretton,Organisms during their early stages exhibit self-directed development, or in other words development “from within”; but the zygote's development until the four to eight cell stage is externally directed by the mother's RNA (inherited from the ovum), and so the zygote during this phase is not an organism.(2008, p. 797)
Preimplantation Genetic Testing of Aneuploidies (PGT-A)
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Daniela N. Bakalova, Darren K. Griffin, Maria E. Póo, Alan R. Thornhill
The blastomere biopsy approach allows identification of aneuploidies of both maternal and paternal origin: an advantage over PB methodologies. Additionally, blastomere biopsy is the preferred approach for fresh embryo transfer (FET) cycles. Day 3 blastomeres enter an arrest phase at the eight-cell stage, during which cell growth, DNA duplication, and protein synthesis take place [32]. This state is maintained for a period long enough to allow preimplantation analysis before progression to the blastocyst stage (day 5) and subsequent embryo transfer.
Connecting lines from a medical point of view
Published in Elisabeth Hildt, Dietmar Mieth, In Vitro Fertilisation in the 1990s, 2018
Although preconception genetic diagnosis has a number of clear advantages, embryo biopsy is needed in the following situations: (1) If the paternal allele cannot be analysed. (2) If there is a possibility that the test will not be effective for telomeric loci because of the likelihood of a high cross-over frequency resulting in a heterozygous state of the polar body. (3) If gender determination is needed. Further indications for this procedure are mentioned in the section on indications for PID. Embryo biopsy performed at the four- to eight-cell stage then becomes an indispensable complement to preconception genetic analysis. Using standard IVF techniques to obtain multiple embryos for analysis, embryo biopsy is usually performed 3 days after retrieval (Black 1994) and ET on the same day or one day later depending on the complexity of the genetic tests needed. Embryo cryopreservation is available if more time is needed to arrive at a reliable test result. Thereafter, the unaffected embryos can be transferred in a future cycle. Human blastocyte biopsy was first undertaken by Dokras et al. (1990). The trophoectoderm cells can be biopsied without affecting the inner cell mass from which the embryo is derived. Despite these advantages, this method has hardly ever been used in humans. Pregnancy rates following transfer of blastocytes remain very low (Verlinsky et al. 1993).
Exploration of novel heterofused 1,2,4-triazine derivative in colorectal cancer
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2021
Justyna Magdalena Hermanowicz, Anna Szymanowska, Beata Sieklucka, Robert Czarnomysy, Krystyna Pawlak, Anna Bielawska, Krzysztof Bielawski, Joanna Kalafut, Alicja Przybyszewska, Arkadiusz Surazynski, Adolfo Rivero-Muller, Mariusz Mojzych, Dariusz Pawlak
The antiproliferative activity of MM-129 and the reference drugs (RSC, 5-FU) were also examined in a zebrafish embryo model (Figure 3). At a constant temperature of 28.5 °C (ST), the ZF egg cleaves first at 45 min post fertilisation forming the two-cell stage egg. Zebrafish embryos reach 4-cell, 8-cell, and 64-cell stages within 1, 1.25, and 2 h post fertilisation (hpf), respectively. Subsequently, they enter into the blastula stage (2.25–5.25 hpf), the gastrula stage (5.25–10 hpf), and the segmentation stage (10–24 hpf) to finally hatch out between 48 and 72 hpf30,31. In untreated eggs, we observed normal embryo development revealed in consecutive synchronous cleavages. This process was disturbed in embryos exposed to MM-129, RSC, and 5-FU. At 1 hpt (hours post treatment), MM-129-treated eggs showed a deterioration of cell division, cell disorientation, and initial signs of cell fusion. Within the next 30 min, fusion dramatically progressed in MM-129-treated eggs, while the control eggs continued cell division without any apparent delay. When zebrafish eggs were treated with RSC and 5-FU, they developed normally for 1 h up to the four-cell stage, and then at the eight-cell stage they showed proliferation arrest. After two hours of incubation, we noticed complete cell fusion and lysis in groups exposed to MM-129 and RSC. 5-FU did not show such strong changes during the study period. No alteration in cell division and development in untreated control eggs were observed.
The effect of human papilloma virus vaccination on embryo yield and clinical in vitro fertilisation outcomes: a matched retrospective cohort study
Published in Journal of Obstetrics and Gynaecology, 2021
Mustafa Demir, Onur Ince, Bulent Yilmaz, Wim Decleer, Kaan Osmanagaoglu
For culturing the embryos, either G1 Plus (Vitrolife) or ISM1 (Origio) was used. ET was performed on day 3 after fertilisation. The exception to this rule was patients with repeated failure of implantation or patients who lacked a sufficient number of good quality embryos. For these patients, blastocyst culture was chosen with ET on day 5 after pick-up. If only one or two embryos were available, they were transferred on the second day after fertilisation (<5%). The number of transferred embryos varied from one to three, in accordance with Belgian laws. Supernumerary embryos of quality type A or B, with less than 10% fragmentation, and seven- to eight-cell stage on day 3 or blastocyst stage on day 5 were frozen (slow freezing with cryogenesis).
Molecular cloning, characterization of dax1 gene and its response to progesterone in Misgurnus anguillicaudatus
Published in Drug and Chemical Toxicology, 2019
Weiran Huo, Ruyan Wan, Peijin Wang, Linxia Zhang, Xiaohua Xia
Whole-mount in situ hybridization was carried out under high stringency conditions to examine the distribution of Ma-dax1 during embryogenesis (Figure 4). Transcripts for Ma-dax1 mRNA first accumulated in the eight cell stage (Figure 4(A)), and then accumulated in the hemisphere after the entry into blastula stage (Figure 4(C)). After tail-bud formed stage, Ma-dax1 was expressed broadly in the central nervous system (Figure 4(E–I)). Ma-dax1 expression was localized in the rostral and basal region of forebrain, midbrain and the hindbrain.