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Is the Human Embryo an Organism?
Published in Nicholas Colgrove, Bruce P. Blackshaw, Daniel Rodger, Agency, Pregnancy and Persons, 2023
The fact that early cells of mammalian embryos remain “plastic”, or are able to adopt a range of new identities if challenged with new developmental signals, has been used to argue that prior to the blastocyst stage when developmental fates become fixed, all cells in the embryo are “equivalent”. This, in turn, has called into question the conclusion that human embryonic development (and therefore, human life) begins at sperm-egg fusion. For example, in an influential article on the nature of human embryos, the philosopher Berit Brogaard rejects the possibility that early embryos are whole, developing organisms stating, “The problem with this proposal is that the cells in the early embryo form a mere mass, being kept together spatially by an outer membrane. There is no causal interaction between the cells” (Brogaard 2002). Similarly, the report of the Warnock Commission that established the national policy for embryo research in the United Kingdom concluded, “A human embryo cannot be thought of as a person, or even as a potential person. It is simply a collection of cells” (Warnock 1984, p. 62). Based on this reasoning, some have concluded that prior to committed cell identities arising, there is no embryo but only a “pre-embryo”—i.e., a collection of “identical” cells that (it is asserted) are not actively undergoing a developmental sequence.8
De Fabrica Humani Corporis—Fascia as the Fabric of the Body
Published in David Lesondak, Angeli Maun Akey, Fascia, Function, and Medical Applications, 2020
The interstitium is the third dimension of fascia and mesenchyme. It comprises a vast inner space that can be found everywhere between organs and tissue elements. It could be regarded as one continuous inter-anatomical body cavity along which chemical transport, communication, and organization are possible by means of various cellular substances.22,24 From embryology we know that signaling proteins are organized and distributed via the mesenchyme. During human embryonic development the meso provides the metabolic conditions for the development of the ectodermal structures and plays a role in their differentiation.21 Perhaps even epigenetic control molecules could be established via diffusion through the interstitial space.
Preimplantation Genetic Testing for Aneuploidies: Where We Are and Where We're Going
Published in Darren K. Griffin, Gary L. Harton, Preimplantation Genetic Testing, 2020
Andrea Victor, Cagri Ogur, Alan Thornhill, Darren K. Griffin
As these technologies allow us to gain invaluable insights into early human embryonic development, we may also gain insight into the populations we treat. Combining our findings with those from companies like Previvo Genetics, Inc. that have developed techniques to recover embryos conceived in vivo in order to perform PGT may help further the discussions of the dissonance between in vitro and in vivo conceptuses, and fertile vs. infertile populations, potentially leading to improvements in the ways we perform IVF and treat different subsets of patients.
The effects and molecular mechanism of heat stress on spermatogenesis and the mitigation measures
Published in Systems Biology in Reproductive Medicine, 2022
Yuanyuan Gao, Chen Wang, Kaixian Wang, Chaofan He, Ke Hu, Meng Liang
Abdominal wall defects (AWDs) are relatively rare congenital malformations. The two most dangerous conditions are gastric fissure and umbilical distention, as these two symptoms can be life-threatening at any time. Boys with congenital AWDs have a significantly higher risk of cryptorchidism (Yardley et al. 2012). As the increased intraperitoneal pressure is a supportive factor for testicular migration, and when the abdominal cavity is damaged, it will lead to decreased pressure in the abdominal cavity and induce symptoms of cryptorchidism (Kaplan et al. 1986; Raitio et al. 2021). The process of descending the testicles is a complex multifactorial event. In human embryonic development, the testicle needs the guidance of abdominal pressure to descend from the abdomen to the scrotum (Logsdon et al. 2021). Studies have shown that patients with abdominal wall defects experience cryptorchidism in more than 30% of cases (Logsdon et al. 2021).
The gene mutations and subtelomeric DNA methylation in immunodeficiency, centromeric instability and facial anomalies syndrome
Published in Autoimmunity, 2019
Haochang Hu, Chujia Chen, Shanping Shi, Bin Li, Shiwei Duan
In the vicinity of the telomeres is the so-called subtelomeric region, which is defined as 500 kb region of each autosomal arm terminal [39]. Both telomere and subtelomeric sequences have high-density DNA repeats, but telomeres do not contain genes or CpG dinucleotides, while subtelomeres contain small amounts of genes and CpG-enriched sequences [40] where DNA methylation often occurs [41,42]. The telomeric DNA and their related proteins play an important role in genome stability and chromosome replication. Similarly, subtelomeric DNA fragments can partially regulate key biological activities, including cell cycle regulation, cell senescence and immortalization, movement and localization of chromosomes within the nucleus, and transcription of subtelomeric genes [43]. In the early stages of human embryonic development, methylation of the subtelomeric region is primarily established and maintained by the DNA methyltransferase (DNMT) family, including DNMT1, DNMT3A, and DNMT3B [44]. Subtelomeric DNA methylation is critical for maintaining normal cell growth and metabolism, and the subtelomeric DNA methylation in some regions is related to the elongation or shortening of telomeres [18]. Besides, mutations in these enzymes are associated with many human diseases such as cancer, immunodeficiency, and neurological diseases [45,46]
The role of the gut microbiota in schizophrenia: Current and future perspectives
Published in The World Journal of Biological Psychiatry, 2018
Daniela Rodrigues-Amorim, Tania Rivera-Baltanás, Benito Regueiro, Carlos Spuch, María Elena de las Heras, Raul Vázquez-Noguerol Méndez, Maria Nieto-Araujo, Carolina Barreiro-Villar, Jose Manuel Olivares, Roberto Carlos Agís-Balboa
Epigenetics is a concept that attempts to extrapolate the dynamic interaction between genetic factors, environmental factors (exposure to toxics agents, diseases, drugs, etc.) and lifestyle (diet, stress, exercise, etc.). It is currently well known that the phenotype is a consequence of complex interactions between the epigenome, genotype and environment (Shenderov 2012). Schizophrenia is linked to external factors such as the time of birth, geographic variation (place of birth and lives), immigration and the use of certain substances (alcohol, drugs, etc.) (Weder et al. 2014; Bahari-Javan et al. 2017). Factors such as infections (influenza virus), malnutrition, obstetric complications and stress are all experiences involved in schizophrenia (Bahari-Javan et al. 2017). Divergent trajectories in psychopathologies may be related to transgenerational inheritance (Boyce and Kobor 2015). Intergenerational transmission of phenotypes linked to psychiatric diseases is common, implying a direct exposure to stressors of the parental generation (Klengel et al. 2016). Human embryonic development depends on the epigenetic programming that controls gene expression, mediated by recognition of the group of molecular mechanisms underlying gene–environment interactions (Boyce and Kobor 2015).