Extraembryonic tissues have pivotal roles in morphogenesis and patterning of the early mammalian embryo. Developmental programmes mediated through signalling pathways and gene regulatory networks determine the sequence in which fate determination and lineage commitment of extraembryonic tissues take place, and epigenetic processes allow the memory of cell identity and state to be sustained throughout and beyond embryo development, even extending across generations. In this Review, we discuss the molecular and cellular mechanisms necessary for the different extraembryonic tissues to develop and function, from their initial specification up until the end of gastrulation, when the body plan of the embryo and the anatomical organization of its supporting extraembryonic structures are established. We examine the interaction between extraembryonic and embryonic tissues during early patterning and morphogenesis, and outline how epigenetic memory supports extraembryonic tissue development.
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http://dx.doi.org/10.1038/s41580-024-00809-w | DOI Listing |
Hum Mol Genet
January 2025
Biomedical Research Centre, School of Biological Sciences, University of East Anglia, Norwich Research Park, Earlham Road, Norwich NR4 6PN, United Kingdom.
Genomic imprinting is the parent-of-origin dependent monoallelic expression of genes often associated with regions of germline-derived DNA methylation that are maintained as differentially methylated regions (gDMRs) in somatic tissues. This form of epigenetic regulation is highly conserved in mammals and is thought to have co-evolved with placentation. Tissue-specific gDMRs have been identified in human placenta, suggesting that species-specific imprinting dependent on unorthodox epigenetic establishment or maintenance may be more widespread than previously anticipated.
View Article and Find Full Text PDFDevelopment
January 2025
Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
In chick embryos before primitive streak formation, the outermost extra-embryonic region, known as the area opaca (AO), was generally thought to act only by providing nutrients and mechanical support to the embryo. Immediately internal to the AO is a ring of epiblast called the marginal zone (MZ), separating the former from the inner area pellucida (AP) epiblast. The MZ does not contribute cells to any part of the embryo but is involved in determining the position of primitive streak formation from the adjacent AP epiblast.
View Article and Find Full Text PDFLife Sci Alliance
March 2025
https://ror.org/05f950310 Department of Development and Regeneration, Stem Cell Institute, KU Leuven, Leuven, Belgium
Mammalian pre-implantation development is entirely devoted to the specification of extra-embryonic lineages, which are fundamental for embryo morphogenesis and support. The second fate decision is taken just before implantation, as defined by the epiblast (EPI) and the primitive endoderm (PE) specification. Later, EPI forms the embryo proper and PE contributes to the formation of the yolk sac.
View Article and Find Full Text PDFAfr J Reprod Health
December 2024
Department of Obstetrics and Gynecology, Changshu Hospital Affiliated to Nanjing University of Chinese Medicine,Changshu 215500, Jiang Su,China.
The study was designed to appraise the effects of early antibiotic administration on reproductive tract infections and fetal membrane cell scorching in instances of premature rupture of membranes (PROM). A total of 107 pregnant women diagnosed with PROM between July 2020 and June 2022 were randomly assigned to two groups: the Intervention (n=54), where ampicillin were administered within 24 hours of PROM onset, and the control group (n=53), where ampicillin were given 24-48 hours after PROM. Maternal and neonatal outcomes, incidence of reproductive tract infections, and fetal membrane cell scorching indicators (Caspase-1, Caspase -3, Caspase-9 and IL-β) were compared.
View Article and Find Full Text PDFAnn Anat
December 2024
Department of Anatomy, School of Life Dentistry at Tokyo, The Nippon Dental University, Tokyo, Japan. Electronic address:
Background: Erythroid cells contribute to embryonic organ development and adult tissue repair supplying oxygen to tissues. During mouse development, the primitive erythroid cells produced in the extraembryonic blood islands of the yolk sac begin to circulate as immature and nucleated erythroblasts with the onset of cardiac contractions around embryonic day 9.5 (E9.
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