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This case study was written for an introductory course for biology majors who are first learning about embryonic development. The case is composed of several parts and involves a storyline about a team of researchers who find frogs and eggs in bamboo plants during a field study. Students consider what these observations mean, learn basics about the stages of animal embryonic development, and make connections to phylogeny and natural selection. Students then apply their understanding of animal embryonic stage development to the chemical atrazine in the environment by examining data from several experiments. As a concluding activity students write a letter to an agency or newspaper of their choosing stating their opinion surrounding the use of atrazine in the environment. The case proceeds in a progressive disclosure format and involves a combination of class discussion, small group work, and homework. Because the case focuses on very basic animal embryonic development, it would also be a great start to a developmental biology course or an embryology course.

This page shows some key events of human development during the embryonic period of the first eight weeks (weeks 1 - 8) following fertilization. This period is also considered the organogenic period, when most organs within the embryo have begun to form. There are links to more detailed descriptions which can be viewed in a week by week format, by the Carnegie stages or integrated into a Timeline of human development. Online resources available include: individual images of all Carnegie stages, scanning electron micrographs of the earlier stages, cross-sections showing internal structures at mid- and late-embryonic, 3D reconstructions of internal structures, animations of processes, ultrasound scans and information about abnormalites of development.

2:18 Human embryonic development depends on stem cells. During the course of development, cells divide, migrate, and specialize. Early in development, a group of cells called the inner cell mass (ICM) forms. These cells are able to produce all the tissues of the body. Later in development, during gastrulation, the three germ layers form, and most cells become more restricted in the types of cells that they can produce.

The early stages of embryonic development shape our cells and tissues for life. It is during this time that our newly formed cells are transformed into heart, skin, nerve or other cell types. Scientists are finding that this process is largely controlled not by the genome, but by the epigenome, chemical markers on DNA that tell cells when to turn genes on and off. Now, studying zebrafish embryos, researchers at Washington University School of Medicine in St. Louis have shown that the epigenome plays a significant part in guiding development in the first 24 hours after fertilization.

This 5 lesson unit, which was designed by teachers in conjunction with scientists, ethicists, and curriculum developers, explores the scientific and ethical issues involved in stem cell research. The unit begins with an exploration of planaria as a model organism for stem cell research. Next, students identify stages in the development of human embryos and compare the types and potency of stem cells. Students learn about a variety of techniques used for obtaining stem cells and the scientific and ethical implications of those techniques. While exploring the ethics of stem cell research, students will develop an awareness of the many shades of gray that exist among positions of stakeholders in the debate. Students will be provided an opportunity to become familiar with policies and regulations for stem cell research that are currently in place in the United States, the issues regarding private and public funding, and the implications for treatment of disease and advancement of scientific knowledge. The unit culminates with students developing a position on embryonic stem cell research through the use of a Decision-Making Framework. Two culminating assessments are offered: In the individual assessment, students write a letter to the President or the President's Bioethics Committee describing their position and recommendations; In the group assessment, students develop a proposal for NIH funding to research treatment for a chosen disease using either embryonic or 'adult' stem cells.

The most recent human retroviral infections leading to germ line integration took place with a subgroup of human endogenous retroviruses called HERVK(HML-2). The human genome contains ~90 copies of these viral genomes, which might have infected human ancestors as recently as 200,000 years ago. HERVs do not produce infectious virus: not only is the viral genome silenced - no mRNAs are produced - but they are littered with lethal mutations that have accumulated over time. A recent study revealed that HERVK mRNAs are produced during normal human embryogenesis. Viral RNAs were detected beginning at the 8-cell stage, through epiblast cells in preimplantation embryos, until formation of embryonic stem cells (illustrated). At this point the production of HERVK mRNA ceases. Viral capsid protein was detected in blastocysts, and electron microscopy revealed the presence of virus-like particles similar to those found in reconstructed HERVK particles. These results indicate that retroviral proteins and particles are present during human development, up until implantation.

  Stem cells are the cells that have an ability to become various types of cells. They are present both during embryonic development (embryonic stem cells) and in the adult body (adult stem cells).

Phys.org) -Scientists at the University of Virginia School of Medicine have overcome one of the greatest challenges in biology and taken a major step toward being able to grow whole organs and tissues from stem cells. By manipulating the appropriate signaling, the U.Va. researchers have turned embryonic stem cells into a fish embryo, essentially controlling embryonic development.

LifeMap Discovery® is a compendium of embryonic development for stem cell research and regenerative medicine, constructed by integrating extensive molecular, cellular, anatomical and medical data curated from scientific literature and high-throughput data sources.

In a retrospective cohort study investigating the role of epigenetic control in the onset of allergic diseases, it was shown that mothers who suffered from allergic symptoms very early in pregnancy were more likely to have offspring with allergies. This was compared to mothers who did not suffer from allergies in early pregnancy, taking into account family history of allergies and total allergic response during pregnancy (10). These results indicate that gene-environment interactions during embryonic development may modify the epigenetic code in ways that may potentially lead to allergic disease.

The team, led by senior authors Qi Zhou and Xiao-Yang Zhao, both from the Institute of Zoology at the Chinese Academy of Sciences, took embryonic stem cells from mice and treated them to a series of carefully worked out steps that included first exposing the stem cells to testicular cells in newly born male mice. The scientists then recreated the chemical environment that sperm cells need to grow, including early development factors and sex hormones including testosterone, follicle stimulating hormone and a growth factor from the pituitary gland.

Over recent decades, scientists have made various discoveries about DNA methylation and how vital it is to a number of cellular processes such as embryonic development, X-chromosome inactivation, genomic imprinting, gene suppression, carcinogenesis and chromosome stability. Researchers have linked abnormal DNA methylation to several adverse outcomes, including human diseases.

The Australian Stem Cell Centre (ASCC), developed the following fact sheets in respect of stem cell science and related topics. Please note that whilst the Fact Sheets were updated shortly before the ASCC closed in 2011, users should note that they are no longer being updated and be aware that the content in them may be out of date. Although the content of the fact sheets is unlikely to have been superseded please do not rely on them for any decision-making purposes and they should be used as part of a wider reading program on the subjects.