Embryo Project Encyclopedia Articles

Sir John Bertrand Gurdon further developed nuclear transplantation, the technique used to clone organisms and to create stem cells, while working in Britain in the second half of the twentieth century. Gurdon's research built on the work of Thomas King and Robert Briggs in the United States, who in 1952 published findings that indicated that scientists could take a nucleus from an early embryonic cell and successfully transfer it into an unfertilized and enucleated egg cell. Briggs and King also concluded that a nucleus taken from an adult cell and similarly inserted into an unfertilized enucleated egg cell could not produce normal development. In 1962, however, Gurdon published results that indicated otherwise. While Briggs and King worked with Rana pipiens frogs, Gurdon used the faster-growing species Xenopus laevis to show that nuclei from specialized cells still held the potential to be any cell despite its specialization. In 2012, the Nobel Prize Committee awarded Gurdon and Shinya Yamanaka its prize in physiology and medicine for for their work on cloning and pluripotent stem cells.

Carol Widney Greider studied telomeres and telomerase in the US at the turn of the twenty-first century. She worked primarily at the University of California, Berkeley in Berkeley, California.
She received the Nobel Prize in Physiology or Medicine in 2009, along with Elizabeth Blackburn and Jack Szostak, for their research on telomeres and telomerase. Telomeres are repetitive sequences of
DNA at the ends of chromosomes that protect chromosomes from tangling, and they provide some protection from mutations. Greider also studied telomerase, an enzyme that repairs telomeres. Without telomeres, chromosomes are subject to mutations that can lead to
cell death, and without telomerase, cells might not reproduce fast enough during embryonic development. Greider's research on telomeres helped scientists explain how chromosomes function within cells.

Telomerase is an enzyme that regulates the lengths of telomeres in the cells of many organisms, and in humans it begins to function int the early stages of embryonic development. Telomeres are repetitive sequences of DNA on the ends of chromosomes that protect chromosomes from sticking to each other or tangling. In 1989, Gregg Morin found that telomerase was present in human cells. In 1996, Woodring Wright and his team examined human embryonic cells and found that telomerase was active in them. Scientists manipulate telomerase in cells to give cells the capacity to replicate infinitely. Telomerase is also necessary for stem cells to replicate themselves and to develop into more specialized cells in embryos and fetuses.

"Casti Connubii," a papal encyclical given by Pope Pius XI on 31 December 1930, served primarily as a reaffirmation and expansion of the issues discussed in Arcanum, an encyclical written by Pope Leo XIII. It was released to address new threats to marriage and conjugal unity, and indeed is translated "On Christian Marriage" or "On Chastity in Marriage." The document explores the meaning of Christian marriage and emphasizes its threefold purpose as borrowed from St. Augustine: to produce offspring, to grow in conjugal faith, and to show benefit from the sacrament. It begins by exploring the nature of marriage, followed by a discussion of its advantages for individuals and societies, erroneous but common beliefs about marriage, threats to pure marriage, and finally how to address them. Included in the threats to pure marriage is that of the growing popularity of contraception and abortive procedures, at which point Pope Pius XI elaborates on the Church' s statement that life begins at conception.

To educate its citizens about research into chimeras made from human and non-human animal cells, the United Kingdom's Human Fertilisation Embryology Authority published the consultation piece Hybrids and Chimeras: A Consultation on the Ethical and Social Implications of Creating Human/Animal Embryos in Research, in 2007. The document provided scientific and legal background, described ethical and social issues associated with research using part-human part-animal embryos, supplied a questionnaire for citizens to return to the HFEA with their opinions, and offered a list of resources for further reading to stimulate public debate. The strategy of surveying the public provided a template for developing further policy in the United Kingdom and other countries, as well as for educating citizens on embryological research.

The General Embryological Information Service (GEIS) was an annual report published by the Hubrecht Laboratory in Utrecht, The Netherlands from 1949 to 1981 that disseminated contemporary research information to developmental biologists. The purpose of the annual report was to catalog the names, addresses, and associated research of every developmental biologist in the world. Pieter Nieuwkoop edited each issue from 1949 until 1964, when Job Faber began assisting Nieuwkoop. Bert Z. Salome joined the editing team in 1968 before Nieuwkoop ceased editing duties in 1971. Faber and Salome remained the editors from 1971 until the periodical's final year of circulation in 1981. The Hubrecht Laboratory, a national laboratory created to house a large collection of comparative embryological materials and loan them to interested researchers, sponsored the publication after World War II to facilitate international collaboration and prevent unnecessary duplication of work. The catalog of researchers and the scientific topics grew in number and variety as the field of developmental biology changed during the publication's thirty-two year history.

First manufactured in 1988 by Serono laboratories, recombinant gonadotropins are synthetic hormones that can stimulate egg production in women for use in fertility treatments. Recombinant gonadotropins are artificially created using recombinant DNA technology, a technology that joins together DNA from different organisms. In vertebrates, naturally-occurring gonadotropins regulate the growth and function of the gonads, known as testes in males and ovaries in females. Medical professionals can derive female gonadotropins from the urine of pregnant and post-menopausal women, often using it to facilitate in vitro fertilization, or IVF. With the rapid development of assisted reproductive technologies like IVF, demand for human-derived gonadotropins rose to a global yearly demand of 120 million liters of urine by the beginning of the twenty-first century, which resulted in a demand that could not be met by traditional technologies at that time. Therefore, researchers created recombinant gonadotropins to establish a safer and more consistent method of human gonadotropin collection that met the high demand for its use in fertility treatments.

Rosalind Elsie Franklin worked with X-ray crystallography at King's College London, UK, and she helped determine the helical structure of DNA in the early 1950s. Franklin's research helped establish molecular genetics, a field that investigates how heredity works on the molecular level. The discovery of the structure of DNA also made future research possible into the molecular basis of embryonic development, genetic disorders, and gene manipulation.

Research in chemical induction seeks to identify the compound or compounds responsible for differentiation in a developing embryo. Soren Lovtrup compared the search for these compounds to the search for the philosopher's stone. It was based on the assumption that the differentiating agents have to be chemical substances either within cells or in the extracellular matrix. However, despite numerous efforts to understand them, the nature of these substances remained largely a mystery from the 1930s until the 1980s, when the new era of molecular induction based on molecular genetics provided a new perspective. During the period of emphasis on chemical induction, a variety of different experiments were conducted aimed at discovering the chemical nature of the inducer. In some experiments, the organizer region was killed by heat to assess the inducing ability of a dead organizer. Other experiments used natural and synthetic compounds to attempt. Although none of these experiments identified a chemical inducer with any certainty, they did discover many related properties of the developing embryo.

Ovarian hyperstimulation syndrome, abbreviated OHSS, is an atypical reaction that women may experience in response to excessive hormones, and often occurs during fertility treatments. OHSS is typically triggered by hormonal medications designed to mature eggs in the ovaries, which can cause blood vessels within the ovaries to leak fluid. Sometimes that can lead to painful tenderness or swelling. In severe cases of OHSS, that fluid can leak into the abdominal cavity in large amounts, causing vomiting, blood clots, and severe pain. As many as one out of three women undergoing fertility treatment will experience some form of OHSS, although more severe presentations are rare. While the exact cause of OHSS is not fully understood as of 2020, researchers continue to discover various risk factors, prevention techniques, and treatments that may lead to decreased risks associated with OHSS and better fertility outcomes.