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Displaying 176 - 200 of 320 items.

Rosalind Elsie Franklin (1920-1958)

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.

Format: Articles

Subject: People

Benjamin Harrison Willier (1890-1972)

Benjamin Harrison Willier is considered one of the most versatile embryologists to have ever practiced in the US. His research spanned most of the twentieth century, a time when the field of embryology evolved from being a purely descriptive pursuit to one of experimental research, to that of incorporating molecular biology into the research lab. Willier was born on 2 November 1890 near Weston, Ohio to Mary Alice Ricard. He spent his childhood doing farming chores and running the farm while his father, David Willier worked as a banker.

Format: Articles

Subject: People

Walter Jakob Gehring (1939-2014)

Walter Jakob Gehring discovered the homeobox, a DNA segment found in a specific cluster of genes that determine the body plan of animals, plants, and fungi. Gehring identified the homeobox in 1983, with the help of colleagues while isolating the Antennapedia (Antp) gene in fruit flies (Drosophila) at the University of Basel in Basel, Switzerland. Hox genes, a family of genes that have the homeobox, determine the head-to-tail (anterior-posterior) body axis of both vertebrates and invertebrates.

Format: Articles

Subject: People

Julia Barlow Platt (1857-1935)

Julia Barlow Platt studied neural crests in animal embryos and became involved in politics in the US during the nineteenth and twentieth centuries. She researched how body and head segments formed in chicks (Gallus gallus) and spiny dogfish (Squalus acanthias). Platt observed that in the mudpuppy (Necturus maculosus), the coordinated migration of neural crest cells in the embryo produced parts of the nervous system, bones, and connective tissues in the head.

Format: Articles

Subject: People

Alfred Henry Sturtevant (1891–1970)

Alfred Henry Sturtevant studied heredity in fruit flies in the US throughout the twentieth century. From 1910 to 1928, Sturtevant worked in Thomas Hunt Morgan’s research lab in New York City, New York. Sturtevant, Morgan, and other researchers established that chromosomes play a role in the inheritance of traits. In 1913, as an undergraduate, Sturtevant created one of the earliest genetic maps of a fruit fly chromosome, which showed the relative positions of genes along the chromosome.

Format: Articles

Subject: People

Katharina Dorothea Dalton (1916–2004)

Katharina Dorothea Dalton was a physician in England in the twentieth century who defined premenstrual syndrome (PMS) as a cluster of symptoms suspected to begin one to two weeks before menstruation and disappear upon the onset of a new menstrual cycle. Prior to Dalton, there was little research on pre-menstrual issues and those that existed linked the problem to excessive water retention or estrogen. Dalton hypothesized that PMS resulted from a deficiency in the hormone progesterone and advocated for hormone replacement therapy to lessen the symptoms of the syndrome.

Format: Articles

Subject: People

Jeffrey Keenan (1961- )

Jeffrey Keenan is the Director of the Southeastern Center for Fertility and Reproductive Medicine and the main developer behind the National Embryo Donation Center (NEDC) in Knoxville, Tennessee. This non-profit organization focuses on embryo donation and embryo adoption.

Format: Articles

Subject: People, Reproduction

Theodora (Theo) Emily Colborn (1927-2014)

Theodora Colborn studied how chemicals affect organisms as they develop and reproduce during the twentieth and twenty first centuries in the US. By the 1940s, researchers had reported that chemicals from agricultural and industrial processes affected how wild organisms developed, but in 1991, Colborn organized the Wingspread Conference in Racine, Wisconsin, at which a group of scientists classed these chemicals as environmentally harmful substances. Colborn and her colleagues called those chemicals endocrine disruptors, as they mimic or block the body's endocrine system.

Format: Articles

Subject: People

Roy Chapman Andrews (1884-1960)

Roy Chapman Andrews traveled the world studying fossils, from mammals to dinosaurs, during the first half of the twentieth century. Andrews worked and collected fossil specimens for the American Museum of Natural History (AMNH) in New York City, New York. Throughout his career, Andrews collected bones of many animal species, including a previously unknown species of a horned, herbivorous dinosaur, later named Proceratops andrewsi in his honor. Andrews published widely read narratives about his travels and field experiences, such as On the Trail of Ancient Man and Across Mongolian Plains.

Format: Articles

Subject: People

Adolf Ziegler

The scientific field of embryology experienced great growth in scope and direction in Germany from approximately 1850 to 1920. During this time, Adolf Ziegler and his son Friedrich crafted hundreds of wax embryo models, representing a shift in how embryos were viewed and used. Their final products, whether human or trout embryos, showcased the now lost collaboration between wax modeling artists and embryologists.

Format: Articles

Subject: People

Johann Friedrich Meckel, the Younger (1781-1833)

Johann Friedrich Meckel studied abnormal animal and human anatomy in nineteenth century Germany in an attempt to explain embryological development. During Meckel's lifetime he catalogued embryonic malformations in multiple treatises. Meckel's focus on malformations led him to develop concepts like primary and secondary malformations, atavism, and recapitulation- all of which influenced the fields of medicine and embryology during the nineteenth and twentieth centuries.

Format: Articles

Subject: People

Michael D. West (1953- )

Michael D. West is a biomedical entrepreneur and investigator whose aim has been to extend human longevity with biomedical interventions. His focus has ranged from the development of telomerase-based therapeutics to the application of human embryonic stem cells in regenerative medicine. Throughout his eventful career, West has pursued novel and sometimes provocative ideas in a fervent, self-publicizing manner. As of 2009, West advocated using human somatic cell nuclear transfer techniques to derive human embryonic stem cells for therapeutic practice.

Format: Articles

Subject: People

Caspar Friedrich Wolff (1734-1794)

Caspar Friedrich Wolff is most famous for his 1759 doctoral dissertation, Theoria Generationis, in which he described embryonic development in both plants and animals as a process involving layers of cells, thereby refuting the accepted theory of preformation: the idea that organisms develop as a result of the unfolding of form that is somehow present from the outset, as in a homunculus. This work generated a great deal of controversy and discussion at the time of its publication but was an integral move in the reemergence and acceptance of the theory of epigenesis.

Format: Articles

Subject: People

Thomas Joseph King Jr. (1921-2000)

Thomas Joseph King Jr. was a developmental biologist who, with fellow scientist Robert Briggs, pioneered a method of transplanting nuclei from blastula cells into fresh egg cells lacking nuclei. This method, dubbed nuclear transplantation, facilitated King's studies on cancer cell development. King's work was instrumental for the development of cloning of fish, insects, and mammals.

Format: Articles

Subject: People

Rudolf Carl Virchow (1821-1902)

Rudolf Carl Virchow lived in nineteenth century Prussia, now Germany, and proposed that omnis cellula e cellula, which translates to each cell comes from another cell, and which became and fundamental concept for cell theory. He helped found two fields, cellular pathology and comparative pathology, and he contributed to many others. Ultimately Virchow argued that disease is caused by changes in normal cells, also known as cellular pathology.

Format: Articles

Subject: People

Ernest John Christopher Polge (1926-2006)

Twentieth-century researcher Ernest John Christopher Polge studied the reproductive processes of livestock and determined a method to successfully freeze, thaw, and utilize viable sperm cells to produce offspring in animals. In 1949, Polge identified glycerol as a cryoprotectant, or a medium that enables cells to freeze without damaging their cellular components or functions. Several years later, Polge used glycerol in a freezing process called vitrification, which enabled him to freeze poultry sperm, thaw that sperm, and use it to fertilize vertebrate embryos.

Format: Articles

Subject: People

Roger Wolcott Sperry (1913–1994)

Roger Wolcott Sperry
studied the function of the nervous system in the US during the
twentieth century. He studied split-brain patterns in cats and
humans that result from separating the two hemispheres of the
brain by cutting the corpus callosum, the bridge between the two
hemispheres of the brain. He found that separating the corpus
callosum the two hemispheres of the brain could not communicate
and they performed functions as if the other hemisphere did not

Format: Articles

Subject: People

Karl Landsteiner (1868-1943)

Karl Landsteiner studied blood types in Europe and in the United States in the late nineteenth and early twentieth centuries. Landsteiner won the Nobel Prize in Physiology or Medicine in 1930 for detailing immunological reactions in the ABO blood group system. The ABO blood group system divides human blood into one of four types based on the antibodies that are present on each cell. Landsteiner's work with blood types led physicians to safely perform blood transfusions and organ transplants.

Format: Articles

Subject: People

John Chassar Moir (1900–1977)

John Chassar Moir lived in Scotland during the twentieth century and helped develop techniques to improve the health of pregnant women. Moir helped to discover compounds that doctors could administer to women after childbirth to prevent life-threatening blood loss. Those compounds included the ergot alkaloid called ergometrine, also called ergonovine, and d-lysergic acid beta-propanolamide. Moir tested ergometrine in postpartum patients and documented that it helped prevent or manage postpartum hemorrhage in women.

Format: Articles

Subject: People, Reproduction, Disorders

Josef Warkany (1902–1992)

Josef Warkany studied the environmental causes of birth defects in the United States in the twentieth century. Warkany was one of the first researchers to show that factors in the environment could cause birth defects, and he helped to develop guidelines for the field of teratology, the study of birth defects. Prior to Warkany’s work, scientists struggled to explain if or how environmental agents could cause birth defects. Warkany demonstrated that a deficiency or excess of vitamin A in maternal nutrition could cause birth defects.

Format: Articles

Subject: People

Catherine DeAngelis (1940– )

In the late-twentieth century in the United States, Catherine DeAngelis was a pediatric physician, researcher, and editor of multiple medical journals. During her time with the Journal of the American Medical Association, DeAngelis became the journal’s first female editor. At Johns Hopkins University in Baltimore, Maryland, she studied how physician-nurse interactions affected patient care, how immunizations and adolescent pregnancy affected children, and how medications affected men and women differently.

Format: Articles

Subject: People

Eric Wieschaus (1947- )

Eric Wieschaus studied how genes cause fruit fly larvae to develop in the US and Europe during the twentieth and twenty-first centuries. Using the fruit fly Drosophila melanogaster, Wieschaus and colleague Christiane Nusslein-Volhard described genes and gene products that help form the fruit fly body plan and establish the larval segments during embryogenesis. This work earned Wieschaus and Nüsslein-Volhard the 1995 Nobel Prize in Physiology or Medicine.

Format: Articles

Subject: People

Johann Friedrich Blumenbach (1752-1840)

In eighteenth century Germany, Johann Friedrich Blumenbach studied how individuals within a species vary, and to explain such variations, he proposed that a force operates on organisms as they develop. Blumenbach used metrical methods to study the history of humans, but he was also a natural historian and theorist. Blumenbach argued for theories of the transformation of species, or the claim that new species can develop from existing forms.

Format: Articles

Subject: People

James William Kitching (1922-2003)

James William Kitching collected and studied fossils of dinosaurs and early humans in the twentieth century. He worked at the Bernard Price Institute for Paleontological Research in South Africa. During the fifty-three years he worked at the institute, Kitching spent eighteen of those in the field uncovering fossils. Kitching recovered fossils of early human ancestors, later called Australopithecines, as well as fossils of dinosaurs and ancient mammals. When he died in 2003, the Bernard Price Institute housed one of the largest fossil collections in the southern hemisphere.

Format: Articles

Subject: People

Alfred Day Hershey (1908–1997)

During the twentieth century in the United States, Alfred Day Hershey studied phages, or viruses that infect bacteria, and experimentally verified that genes were made of deoxyribonucleic acid, or DNA. Genes are molecular, heritable instructions for how an organism develops. When Hershey started to study phages, scientists did not know if phages contained genes, or whether genes were made of DNA or protein. In 1952, Hershey and his research assistant, Martha Chase, conducted phage experiments that convinced scientists that genes were made of DNA.

Format: Articles

Subject: People