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Objections to the Basic Moral Status of Human Embryos
Published in Christopher Kaczor, The Ethics of Abortion, 2023
One difficulty with the bag of marbles analogy is there is evidence that the cells of the early human embryo are interacting with one another and becoming specialized so as to contribute to the development of a mature human body. S. Matthew Liao argues,there are thousands of cells by the time a blastula is formed around the nine-day stage, and certainly many more by the sixteen-day stage. Though by no means metaphysically impossible, it seems highly suspect that these thousands of cells would all be distinct and separate organisms; that they would not be sufficiently coordinated; and that at the sixteen-day stage, all of them would all of a sudden become sufficiently coordinated to compose a single organism.(2010b, p. 64)
Regulation of the Arachidonic Acid Cascade and PAF Metabolism in Reproductive Tissues
Published in Murray D. Mitchell, Eicosanoids in Reproduction, 2020
John M. Johnston, Noriei Maki, Marlane J. Angle, Dennis R. Hoffman
Further studies, using a highly specific and sensitive platelet-serotonin release assay, have shown that mouse embryos in culture produce significant quantities of PAF at a time in culture corresponding to development of the morula.149 This PAF production is modified by the number of embryos present during culture and by the protein source used to make culture media. Embryonic PAF production subsequently decreased as the embryo progressed from the morula to the blastula stage.
Adult Stem Cell Plasticity
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
Strictly defined, a stem cell is a cell capable of extensive self-renewal, enabling it to persist long term, and of differentiation into at least one mature cell type. However, this definition alone is imprecise. There are many different types of stem cells that can be defined by: (1) the stage of differentiation at which they are present; (2) where they are found in the organism; and (3) their differentiative potential. In the 2-4 cell stage of embryogenesis, each of the cells in the blastula is totipotent in that each is capable of differentiating into all embryonic and extraembryonic cell types necessary for development of the fetus. In contrast, stem cells in the adult are traditionally considered to have limited potential. For example, intrahepatic liver stem cells are only thought capable of differentiation into the primary cell types in the liver – hepatocytes and cholangiocytes. At the heart of the debate surrounding adult stem cell plasticity is whether predominantly tissue-specific adult stem cells are capable of differentiating into cell types outside of their primary lineage if in an appropriate microenvironment. To truly understand the debate surrounding BMSC plasticity, one must first understand the role stem cells play in ontogeny and adult physiology.
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.
Radiosensitizer effect of usnic acid on Biomphalaria glabrata embryos
Published in International Journal of Radiation Biology, 2018
F. T. J. Santos, W. N. Siqueira, M. L. O. Santos, H. A. M. F. Silva, J. L. F. Sá, T. S. Fernandes, N. H. Silva, E. J. França, E. B. Silva, A. M. M. A. Melo
Pigmented adult snails of B. glabrata were used, measuring 10–14 mm diameter, from São Lourenço da Mata, Pernambuco and maintained for successive generations in the Radiobiology Laboratory of the Department of Biophysics and Radiobiology of Federal University of Pernambuco. The snails were kept in plastic tanks of approximately 20 L filtered and dechlorinated water, pH 7 and a temperature of about 25 ± 3 °C. The snails were fed daily with fresh organic lettuce (Lactuca sativa). The animals deposited their spawn onto colorless polyethylene strips (5x5 cm) that were floated on the water surface and examined under a stereomicroscope (Tecnival SQZ-SD4, São Paulo, Brazil) for individualization and identification of embryonic stage. After identification, embryos in the blastula stage were collected and divided into groups of 100 ± 3 specimens.
Toxicity assessment of biological suspensions using the dielectric impedance spectroscopy technique
Published in International Journal of Radiation Biology, 2018
S. Muñoz, J. L. Sebastián, P. Antoranz, J. P. García-Cambero, A. Sanchis-Otero
In order to assess the capability of the setup measurement to detect possible variations of the electrical parameters, we have characterized suspensions of ZFe at three different development stages (V1, V2 and V3) and non-viable embryos (NV1, NV2 and NV3) obtained following lethal ethanol exposure of each viable suspension. Figure 4 shows microscope images of the viable and non-viable suspensions: (a) suspension V1, with embryos at earlier stage of the blastula period, between 2.5 and 3.5 h post-fertilization (hpf); (b) suspension V2, with embryos between 3.5 and 4 hpf; (c) suspension V3, with embryos between late blastula period and the onset of gastrula period, from 4.3 to 5.7 hpf and (d) coagulated embryos from any of the non-viable (NV) embryo suspensions.