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Clinical Tests of Estrogen Injections on Women with Abnormal Menstrual Cycles During the Early 1920s by Jean Paul Pratt and Edgar Allen

In the early twentieth century US, Jean Paul Pratt and Edgar Allen conducted clinical experiments on women who had abnormal menstrual cycles. During the clinical tests, researchers injected the hormone estrogen into their patients to alleviate their menstrual ailments, which ranged from irregular cycles to natural menopause. The hormone estrogen plays a prominent role in the menstrual cycle by signaling the tissue lining the uterus (endometrium) to thicken in preparation for possible pregnancy.

Format: Articles

Subject: Experiments

Emil Kraepelin (1856–1926)

Emil Kraepelin was a physician who studied people with mental illness in the late nineteenth and early twentieth centuries in modern-day Germany. Kraepelin's examination and description of the symptoms and outcomes of mental illness formed the basis for his classification of psychiatric disorders into two main groups, dementia praecox, now called schizophrenia, and manic-depressive psychosis, now called bipolar disorder. He was one of the first physicians to suggest that those researching mental illness should gain scientific knowledge only through close observation and description.

Format: Articles

Subject: People, Disorders

Endoderm

Endoderm is one of the germ layers-- aggregates of cells that organize early during embryonic life and from which all organs and tissues develop. All animals, with the exception of sponges, form either two or three germ layers through a process known as gastrulation. During gastrulation, a ball of cells transforms into a two-layered embryo made of an inner layer of endoderm and an outer layer of ectoderm. In more complex organisms, like vertebrates, these two primary germ layers interact to give rise to a third germ layer, called mesoderm.

Format: Articles

Subject: Processes

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

Ectoderm

Ectoderm is one of three germ layers--groups of cells that coalesce early during the embryonic life of all animals except maybe sponges, and from which organs and tissues form. As an embryo develops, a single fertilized cell progresses through multiple rounds of cell division. Eventually, the clump of cells goes through a stage called gastrulation, during which the embryo reorganizes itself into the three germ layers: endoderm, ectoderm, and mesoderm. After gastrulation, the embryo goes through a process called neurulation, which starts the development of nervous system.

Format: Articles

Subject: Processes

Etienne Geoffroy Saint-Hilaire (1772-1844)

Etienne Geoffroy Saint-Hilaire, commonly known as Geoffroy, studied animals, their anatomy and their embryos, and teratogens at the National Museum of Natural History in Paris, France in the eighteenth and nineteenth centuries. Geoffroy also helped develop several specialized fields in the life sciences, including experimental embryology. In his efforts to experimentally demonstrate the theory of recapitulation, Geoffroy developed techniques to intervene in the growth of embryos to see whether they would develop into different kinds of organisms.

Format: Articles

Subject: People

Barbara McClintock (1902-1992)

Barbara McClintock worked on genetics in corn (maize) plants and spent most of her life conducting research at the Cold Spring Harbor Laboratory in Laurel Hollow, New York. McClintock's research focused on reproduction and mutations in maize, and described the phenomenon of genetic crossover in chromosomes. Through her maize mutation experiments, McClintock observed transposons, or mobile elements of genes within the chromosome, which jump around the genome. McClintock received the Nobel Prize for Physiology or Medicine in 1983 for her research on chromosome transposition.

Format: Articles

Subject: People

Ilya Ilyich Mechnikov (Élie Metchnikoff) (1845-1916)

Ilya Ilyich Mechnikov studied phagocytes, immune function, and starfish embryos in Europe during the late nineteenth and early twentieth centuries. Mechnikov adopted the French form of his name, Élie Metchnikoff, in the last twenty-five years of his life. In 1908, he won the Nobel Prize in Physiology or Medicine with Paul Ehrlich for their contributions to immunology. Mechnikov discovered phagocytes, immune cells that protect organisms by ingesting foreign particles or microorganisms, by conducting experiments on starfish larvae.

Format: Articles

Subject: People

Mitochondrial Diseases in Humans

Mitochondrial diseases in humans result when the small organelles called mitochondria, which exist in all human cells, fail to function normally. The mitochondria contain their own mitochondrial DNA (mtDNA) separate from the cell's nuclear DNA (nDNA). The main function of mitochondria is to produce energy for the cell. They also function in a diverse set of mechanisms such as calcium hemostasis, cell signaling, regulation of programmed cell death (apoptosis), and biosynthesis of heme proteins that carry oxygen.

Format: Articles

Subject: Disorders, Reproduction

Ernst Haeckel's Biogenetic Law (1866)

The biogenetic law is a theory of development and evolution proposed by Ernst Haeckel in Germany in the 1860s. It is one of several recapitulation theories, which posit that the stages of development for an animal embryo are the same as other animals' adult stages or forms. Commonly stated as ontogeny recapitulates phylogeny, the biogenetic law theorizes that the stages an animal embryo undergoes during development are a chronological replay of that species' past evolutionary forms.

Format: Articles

Subject: Theories

The Origin of Species: "Chapter Thirteen: Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Organs" (1859), by Charles R. Darwin

Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Organs is the thirteenth chapter of Charles Darwin's book The Origin of Species, first published in England in 1859. The book details part of Darwin's argument for the common ancestry of life and natural selection as the cause of speciation. In this chapter, Darwin summarizes the evidence for evolution by connecting observations of development in organisms to the processes of natural selection.

Format: Articles

Subject: Publications

The Role of the Notch Signaling Pathway in Myogenesis

Among other functions, the Notch signaling pathway forestalls the process of myogenesis in animals. The Notch signaling pathway is a pathway in animals by which two adjacent cells within an organism use a protein named Notch to mechanically interact with each other. Myogenesis is the formation of muscle that occurs throughout an animal's development, from embryo to the end of life. The cellular precursors of skeletal muscle originate in somites that form along the dorsal side of the organism.

Format: Articles

Subject: Theories, Processes

Paul Kammerer (1880-1926)

Paul Kammerer conducted experiments on amphibians and marine animals at the Vivarium, a research institute in Vienna, Austria, in the early twentieth century. Kammerer bred organisms in captivity, and he induced them to develop particular adaptations, which Kammerer claimed the organismss offspring would inherit. Kammerer argued that his results demonstrated the inheritance of acquired characteristics, or Lamarckian inheritance. The Lamarckian theory of inheritance posits that individuals transmit acquired traits to their offspring.

Format: Articles

Subject: Experiments, People

Joseph Bolivar DeLee (1869–1942)

Joseph Bolivar DeLee was an obstetrician in the US between the nineteenth and twentieth centuries who advocated for the specialized teaching of medical students in the field of obstetrics to address problems occurring during pregnancy. He claimed obstetricians maintained a wider skillset than midwives, and founded the Chicago Lying-In Hospital to provide affordable obstetric care to women in Chicago, Illinois.

Format: Articles

Subject: People

Emma Goldman (1869–1940)

Emma Goldman was a traveling public speaker and writer known for her anarchist political views as well as her opinions on contraception and birth limiting in the late nineteenth century in the United States. Goldman identified as an anarchist, which she explained as being part of an ideology in which people use violence to provoke or demand social and political change. Goldman was involved in many anarchist social groups and published the anarchist magazine Mother Earth.

Format: Articles

Subject: People

Ontogeny and Phylogeny (1977), by Stephen Jay Gould

Ontogeny and Phylogeny is a book published in 1977, in which the author Stephen J. Gould, who worked in the US, tells a history of the theory of recapitulation. A theory of recapitulation aims to explain the relationship between the embryonic development of an organism (ontogeny) and the evolution of that organism's species (phylogeny). Although there are several variations of recapitulationist theories, most claim that during embryonic development an organism repeats the adult stages of organisms from those species in it's evolutionary history.

Format: Articles

Subject: Publications

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: Technologies

“Adherence to Combination Prophylaxis for Prevention of Mother-to-Child-Transmission of HIV in Tanzania” (2011), by Inga Kristen, Julius Sewangi, Andrea Kunz, Festo Dugange, Judith Ziske, Brigitte Jordan-Harder, Gundel Harms, and Stefanie Theuring

In 2011, Inga Kristen, Julius Sewangi, Andrea Kunz, Festo Dugange, Judith Ziske, Brigitte Jordan-Harder, Gundel Harms, and Stefanie Theuring published the article, “Adherence to Combination Prophylaxis for Prevention of Mother-to-Child-Transmission of HIV in Tanzania,” in PLoS ONE. Hereafter, “Adherence to Combination Prophylaxis,” the article details the authors’ investigation into the efficacy of a medication regimen called combination prophylaxis to prevent mother-to-child, or MTC, transmission of Human Immunodeficiency Virus, or HIV, before, during, and after delivery.

Format: Articles

Subject: Publications

John D. Gearhart

John D. Gearhart is a renowned American developmental geneticist best known for leading the Johns Hopkins University research team that first identified and isolated human pluripotent stem cells from human primordial germ cells, the precursors of fully differentiated germ cells. Born in Western Pennsylvania, Gearhart lived on the family farm located in the Allegheny Mountains for the first six years of his life.

Format: Articles

Subject: People

Center for Reproductive Health (1986-1995)

The Center for Reproductive Health was a fertility clinic run by a partnership of world-renowned fertility specialists from 1986 to 1995. The Center operated at three clinic locations under affiliation with the University of California Irvine 's Medical Center (UCIMC). The Center's renowned specialists and medical success stories attracted clients worldwide until evidence of highly unethical practices conducted by doctors there resulted in over one hundred lawsuits against the University. At issue was the doctors' misappropriation and unauthorized use of eggs and embryos.

Format: Articles

Subject: Organizations, Reproduction

James Alexander Thomson (1958- )

James Alexander Thomson, affectionately known as Jamie Thomson, is an American developmental biologist whose pioneering work in isolating and culturing non-human primate and human embryonic stem cells has made him one of the most prominent scientists in stem cell research. While growing up in Oak Park, Illinois, Thomson's rocket-scientist uncle inspired him to pursue science as a career. Born on 20 December 1958, Thomson entered the nearby University of Illinois Urbana-Champaign nineteen years later as a National Merit Scholar majoring in biophysics.

Format: Articles

Subject: People

Slime Mold Video

This video is composed of a sequence of films created by John Tyler Bonner in the 1940s to show the life cycle of the cellular slime mold Dictyostelium discoideum. As only the second person to study slime molds, Bonner frequently encountered audiences who had never heard of, let alone seen, the unusual organism.

Format: Articles

Subject: Processes

Embryo Blotting Paper Models

Anatomical models have always been a mainstay of descriptive embryology. As the training of embryologists grew in the late 1800s, so too did the need for large-scale teaching models. Embryo wax models, such as those made by Adolf Ziegler and Gustav Born, were popular in the latter part of the nineteenth century and the early twentieth century as a way to visualize, in three dimensions, the fine detail of embryos without the aid of a microscope.

Format: Articles

Subject: Technologies

Calvin Blackman Bridges (1889-1938)

Calvin Blackman Bridges studied chromosomes and heredity in the US throughout the early twentieth century. Bridges performed research with Thomas Hunt Morgan at Columbia University in New York City, New York, and at the California Institute of Technology in Pasadena, California. Bridges and Morgan studied heredity in Drosophila, the common fruit fly. Throughout the early twentieth century, researchers were gathering evidence that genes, or what Gregor Mendel had called the factors that control heredity, are located on chromosomes.

Format: Articles

Subject: People

Alec John Jeffreys (1950–)

Alec John Jeffreys created a process called DNA fingerprinting in the UK during the twentieth century. For DNA fingerprinting, technicians identify a person as the source of a biological sample by comparing the genetic information contained in the person's DNA to the DNA contained in the sample. Jeffreys developed the technique in the 1980s while at the University of Leicester in Leicester, UK. Jeffreys's technique had immediate applications. In forensic science, DNA fingerprinting enabled police to identify suspects of crimes based on their genetic identities.

Format: Articles

Subject: People