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Joseph Needham (1900-1995)

Joseph Needham was an embryologist and biochemist who is most noted in science for his studies on induction in developing embryos. Needham worked with Conrad Hal Waddington to attempt to identify the compound responsible for the organizer's activity. Although he was not successful in discovering the chemical, he and Waddington learned much about the organizer. Needham was a meticulous writer, writing reviews and books about contemporary research.

Format: Articles

Subject: People

The Effects of Bisphenol A on Embryonic Development

Bisphenol A (BPA) is an organic compound that was first synthesized by Aleksandr Dianin, a Russian chemist from St. Petersburg, in 1891. The chemical nomenclature of BPA is 2,2-bis (4-hydroxyphenyl) propane. The significance of this synthesized compound did not receive much attention until 1936, when two biochemists interested in endocrinology, Edward Dodds and William Lawson, discovered its ability to act as an estrogen agonist in ovariectomized, estrogen-deficient rats.

Format: Articles

Subject: Disorders, Reproduction

Oswald Theodore Avery (1877-1955)

Oswald Theodore Avery studied strains of pneumococcus of the genus Streptococcus in the US in the first half of the twentieth century. This bacterium causes pneumonia, a common cause of death at the turn of the twentieth century. In a 1944 paper, Avery demonstrated with colleagues Colin Munro MacLeod and Maclyn McCarty that deoxyribonucleic acid, or DNA, instead of protein, formed the material of heritable transformation in bacteria. Avery helped untangle some of the relationships between genes and developmental processes.

Subject: People

Study of Fossilized Massospondylus Dinosaur Embryos from South Africa (1978-2012)

In 1978, James Kitching discovered two dinosaur embryos in a road-cut talus at Roodraai (Red Bend) in Golden Gate Highlands National Park, South Africa. Kitching assigned the fossilized embryos to the species of long necked herbivores Massospondylus carinatus (longer vertebra) from the Early Jurassic period, between 200 and 183 million years ago. The embryos were partially visible but surrounded by eggshell and rock, called matrix. Kitching said that the eggs were too delicate to remove from the matrix without damage.

Format: Articles

Subject: Theories, Organisms

Green Fluorescent Protein

Green fluorescent protein (GFP) is a protein in the jellyfish Aequorea Victoria that exhibits green fluorescence when exposed to light. The protein has 238 amino acids, three of them (Numbers 65 to 67) form a structure that emits visible green fluorescent light. In the jellyfish, GFP interacts with another protein, called aequorin, which emits blue light when added with calcium. Biologists use GFP to study cells in embryos and fetuses during developmental processes.

Format: Articles

Subject: Technologies

Wilhelm Johannsen's Genotype-Phenotype Distinction

Wilhelm Johannsen in Denmark first proposed the distinction between genotype and phenotype in the study of heredity in 1909. This distinction is between the hereditary dispositions of organisms (their genotypes) and the ways in which those dispositions manifest themselves in the physical characteristics of those organisms (their phenotypes). This distinction was an outgrowth of Johannsen's experiments concerning heritable variation in plants, and it influenced his pure line theory of heredity.

Format: Articles

Subject: Theories

Wilhelm Ludvig Johannsen (1857-1927)

Wilhelm Ludvig Johannsen studied plants and helped found the field of genetics, contributing methods and concepts to the study of heredity around the turn of the twentieth century in Denmark. His experiments on heredity and variation in plants influenced the methods and techniques of geneticists, and his distinction between the genotype of an organism-its hereditary disposition-and its phenotype-its observable characteristics-remains at the core of contemporary biology. Johannsen criticized biological explanations that relied on concepts such as vitalism and teleology.

Format: Articles

Subject: People

Matthias Jacob Schleiden (1804–1881)

Matthias Jacob Schleiden helped develop the cell theory in Germany during the nineteenth century. Schleiden studied cells as the common element among all plants and animals. Schleiden contributed to the field of embryology through his introduction of the Zeiss microscope lens and via his work with cells and cell theory as an organizing principle of biology.

Format: Articles

Subject: People

Mammography

Mammography or mastography is an imaging technology used in the twentieth century for the detection of breast cancer and other breast abnormalities. Breast cancer is an abnormal growth in breast tissue that can spread to other parts of the body and cause death. Breast cancer affects about twelve percent of women worldwide. In the twenty-first century, mammography is one of the most accurate tools for screening and diagnosing breast cancer.

Format: Articles

Subject: Technology

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

Lysogenic Bacteria as an Experimental Model at the Pasteur Institute (1915-1965)

Lysogenic bacteria, or virus-infected bacteria, were the primary experimental models used by scientists working in the laboratories of the Pasteur Institute in Paris, France, during the 1950s and 1960s. Historians of science have noted that the use of lysogenic bacteria as a model in microbiological research influenced the scientific achievements of the Pasteur Institute's scientists.

Format: Articles

Subject: Organisms, Experiments

Endoscopic Fetoscopy

Endoscopic fetoscopy is a minimally invasive surgical procedure performed during pregnancy that allows physicians to view the fetus in-utero. Physicians use endoscopic fetoscopy to evaluate, diagnose, and treat fetal abnormalities. Physicians use an endoscope, or a thin, flexible surgical device with a light attached to its end, to perform endoscopic fetoscopy procedures. In 1954, Björn Westin performed the first endoscopic fetoscopy in Sweden.

Format: Articles

Subject: Technology

"The Environment and Disease: Association or Causation?" (1965), by Austin Bradford Hill

In 1965, Austin Bradford Hill published the article “The Environment and Disease: Association or Causation?” in the Proceedings of the Royal Society of Medicine. In the article, Hill describes nine criteria to determine if an environmental factor, especially a condition or hazard in a work environment, causes an illness. The article arose from an inaugural presidential address Hill gave at the 1965 meeting of the Section of Occupational Medicine of the Royal Society of Medicine in London, England.

Format: Articles

Subject: Publications

William Withey Gull (1816-1890)

William Withey Gull studied paraplegia, anorexia, and hormones as a physician in England during the nineteenth century. In addition to caring for patients, he described the role of the posterior column of the spinal cord in paraplegia, and he was among the first to describe the conditions of anorexia and of hypochondria. He also researched the effects of thyroid hormone deficiencies in women who had malfunctioning thyroid glands.

Format: Articles

Subject: People

Friedrich Tiedemann (1781-1861)

Friedrich Tiedemann studied the anatomy of humans and animals in the nineteenth century in Germany. He published on zoological subjects, on the heart of fish, the anatomy of amphibians and echinoderms, and the lymphatic and respiratory system in birds. In addition to his zoological anatomy, Tiedemann, working with the chemist Leopold Gmelin, published about how the digestive system functioned.

Format: Articles

Subject: People

The Ponseti Method to Treat Club Foot

Ignacio Vives Ponseti developed a noninvasive method for treating congenital club foot in the US during the late 1940s. Congenital club foot is a birth deformity in which one or both of an infant's feet are rotated inward beneath the ankle, making normal movement rigid and painful. Ponseti developed a treatment method, later called the Ponseti method, that consisted of a series of manipulations and castings of the club foot performed in the first few months of life.

Format: Articles

Subject: Technologies

Nettie Maria Stevens (1861-1912)

Multiple theories about what determines sex were tested at the turn of the twentieth century. By experimenting on germ cells, cytologist Nettie Maria Stevens collected evidence to support the connection between heredity and the sex of offspring. Stevens was able to interpret her data to conclude that chromosomes have a role in sex determination during development. For her time, she was an emerging breed: a woman of science making the leap from the world of data collection to that of male-dominated interpretive work.

Format: Articles

Subject: People, Reproduction

Congenital Vertebral Defects

The spinal column is the central structure in the vertebrate body from which stability, movement, and posture all derive. The vertebrae of the spine are organized into four regions (listed in order from cranial to caudal): cervical, thoracic, lumbar, and pelvic. These regions are classified by their differences in curvature. The human spine usually consists of thirty-three vertebrae, seven of which are cervical (C1-C7), twelve are thoracic (T1-T12), five are lumbar (L1-L5), and nine are pelvic (five fused as the sacrum and four fused as the coccyx).

Format: Articles

Subject: Disorders, Reproduction

"Autistic Disturbances of Affective Contact" (1943), by Leo Kanner

Leo Kanner published Autistic Disturbances of Affective Contact in 1943 in the journal Nervous Child. This article described the cases of eleven children with autism. Kanner described the behavior and upbringing of each child, aged two to eight, as well as the educational backgrounds of the children's.

Format: Articles

Subject: Publications

Maurice Ralph Hilleman (1919–2005)

Maurice Ralph Hilleman developed vaccines at the Merck Institute of Therapeutic Research in West Point, Pennsylvania, during the twentieth century. Over the course of his career at Merck, Hilleman created over forty vaccines, making him one of the most prolific developers of vaccine in the twentieth century. Of the fourteen vaccines commonly given to children in the US by 2015, Hilleman was responsible for eight of them. Hilleman's most widely used vaccine was his measles, mumps, and rubella (MMR) vaccine.

Format: Articles

Subject: People

Trial of Madame Restell (Ann Lohman) for Abortion (1841)

In the spring of 1841, abortionist Ann Lohman, called Madame Restell, was convicted for crimes against one of her abortion clients, Maria Purdy. In a deathbed confession, Purdy admitted that she had received an abortion provided by Madame Restell, and she further claimed that the tuberculosis that she was dying from was a result of her abortion. Restell was charged with administering an illegal abortion in New York and her legal battles were heavily documented in the news.

Format: Articles

Subject: Theories

“Of Pregnancy and Progeny” (1980), by Norbert Freinkel

Norbert Freinkel’s lecture Of Pregnancy and Progeny was published by the American Diabetes Association’s journal Diabetes in December of 1980. In the lecture, Freinkel argued that pregnancy changes the way that the female body breaks down and uses food. Through experiments that involved pregnant women as well as infants, Freinkel established the body’s maternal metabolism and how it affects both the mother and the infant. Freinkel’s main focus of research in the latter part of his life was diabetes, specifically in pregnant women.

Format: Articles

Subject: Publications

David Starr Jordan (1851-1931)

David Starr Jordan studied fish and promoted eugenics in the US during the late nineteenth and early twentieth centuries. In his work, he embraced Charles Darwin s theory of evolution and described the importance of embryology in tracing phylogenic relationships. In 1891, he became the president of Stanford University in Stanford, California. Jordan condemned war and promoted conservationist causes for the California wilderness, and he advocated for the eugenic sterilization of thousands of Americans.

Format: Articles

Subject: People, Reproduction

Sex-determining Region Y in Mammals

The Sex-determining Region Y (Sry in mammals but SRY in humans) is a gene found on Y chromosomes that leads to the development of male phenotypes, such as testes. The Sry gene, located on the short branch of the Y chromosome, initiates male embryonic development in the XY sex determination system. The Sry gene follows the central dogma of molecular biology; the DNA encoding the gene is transcribed into messenger RNA, which then produces a single Sry protein.

Format: Articles

Subject: Processes

Francis Harry Compton Crick (1916-2004)

Francis Harry Compton Crick, who co-discovered the structure of deoxyribonucleic acid (DNA) in 1953 in Cambridge, England, also developed The Central Dogma of Molecular Biology, and further clarified the relationship between nucleotides and protein synthesis. Crick received the Nobel Prize in Physiology or Medicine that he shared with James Watson and Maurice Wilkins in 1962 for their discovery of the molecular structure of DNA.

Format: Articles

Subject: People