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Edwin Stephen Goodrich (1868-1946)
Edwin Stephen Goodrich studied the structures of animals in England during the nineteenth and twentieth centuries. Goodrich studied how animals develop to identify their parts and to establish the evolutionary relationships between different species. Goodrich established that body structures can shift their positions relative to an organism's body during evolution, and he hypothesized that body structures can share ancestry (homology) between organisms of different species, even without identical body placement.
A Series of YouTube Videos Detailing the “CRISPR Babies” Experiment (2018), by He Jiankui
In 2018, He Jiankui uploaded a series of videos to a YouTube channel titled “The He Lab” that detailed one of the first instances of a successful human birth after genome editing had been performed on an embryo using CRISPR-cas9. CRISPR-cas9 is a genome editing tool derived from bacteria that can be used to cut out and replace specific sequences of DNA. He genetically modified embryos at his lab in Shenzhen, China, to make them immune to contracting HIV through indirect perinatal transmission from their father, who was infected with the virus.
Subject: Publications, Experiments, Ethics
The Spemann-Mangold organizer, also known as the Spemann organizer, is a cluster of cells in the developing embryo of an amphibian that induces development of the central nervous system. Hilde Mangold was a PhD candidate who conducted the organizer experiment in 1921 under the direction of her graduate advisor, Hans Spemann, at the University of Freiburg in Freiburg, German. The discovery of the Spemann-Mangold organizer introduced the concept of induction in embryonic development.
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.
Teratomas are embryonal tumors that normally arise from germ cells and are typically benign. They are defined as being composed either of tissues that are foreign to the area in which they form, or of tissues that derive from all three of the germ layers. Malignant teratomas are known as teratocarcinomas; these cancerous growths have played a pivotal role in the discovery of stem cells. "Teratoma" is Greek for "monstrous tumor"; these tumors were so named because they sometimes contain hair, teeth, bone, neurons, and even eyes.
Dr. John Rock, a doctor of obstetrics and gynecology in Boston, and Miriam Menkin, Rock s hired lab technician, were the first researchers to fertilize a human egg outside of a human body in February of 1944. Their work was published on 4 August 1944 in an issue of Science in an article entitled "In Vitro Fertilization and Cleavage of Human Ovarian Eggs." This experiment marked the first time in history that a human embryo was produced outside of the human body, proving that in vitro fertilization was possible in humans.
Subject: Experiments, Reproduction
Spermism was one of two models of preformationism, a theory of embryo generation prevalent in the late seventeenth through the end of the eighteenth century. Spermist preformationism was the belief that offspring develop from a tiny fully-formed fetus contained within the head of a sperm cell. This model developed slightly later than the opposing ovist model because sperm cells were not seen under the microscope until about 1677.
Camillo Golgi (1843–1926)
Camillo Golgi studied the central nervous system during the late nineteenth and early twentieth centuries in Italy, and he developed a staining technique to visualize brain cells. Called the black reaction, Golgi’s staining technique enabled him to see the cellular structure of brain cells, called neurons, with much greater precision. Golgi also used the black reaction to identify structures within animal cells like the internal reticular apparatus that stores, packs, and modifies proteins, later named the Golgi apparatus in his honor.
Carol Widney Greider (1961-)
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
Hermann Joseph Muller (1890-1967)
Hermann Joseph Muller studied the effects of x-ray radiation on genetic material in the US during the twentieth century. At that time, scientists had yet to determine the dangers that x-rays presented. In 1927, Muller demonstrated that x-rays, a form of high-energy radiation, can mutate the structure of genetic material. Muller warned others of the dangers of radiation, advising radiologists to protect themselves and their patients from radiation. He also opposed the indiscriminate use of radiation in medical and industrial fields.
Fetus in Fetu
Fetus in fetu is a rare variety of parasitic twins , where the developmentally abnormal parasitic twin is completely encapsulated within the torso of the otherwise normally developed host twin. In the late eighteenth century, German anatomist Johann Friedrich Meckel was the first to described fetus in fetu, which translates to “fetus within fetus.” Fetus in fetu is thought to result from the unequal division of the totipotent inner cell mass , the mass of cells that is the ancestral precursor to all cells in the body.
Subject: Theories, Disorders, Reproduction
Franklin William Stahl (1929– )
Franklin William Stahl studied DNA replication, bacteriophages, and genetic recombination in the US during the mid-twentieth and early twenty-first centuries. With his colleague Matthew Meselson, Stahl performed an experiment called the Meselson-Stahl experiment, which provided evidence for a process called semi-conservative DNA replication. Semi-conservative replication is a process in which each strand of a parental DNA double helix serves as a template for newly replicated daughter strands, so that one parental strand is conserved in every daughter double helix.
Interspecies SCNT-derived Humanesque Blastocysts
Since the 1950s, scientists have developed interspecies blastocysts in laboratory settings, but not until the 1990s did proposals emerge to engineer interspecies blastocysts that contained human genetic or cellular material. Even if these embryos were not permitted to mature to fetal stages, their ethical and political status became debated within nations attempting to use them for research.
Gene Transfer Strategy Used to Treat Tay - Sachs Disease (2005), by Sabata Martino’s Research Group
In the early 2000s, Sabata Martino and a team of researchers in Italy and Germany showed that they could reduce the symptoms of Tay-Sachs in afflicted mice by injecting them with a virus that infected their cells with a gene they lacked. Tay-Sachs disease is a fatal degenerative disorder that occurs in infants and causes rapid motor and mental impairment, leading to death at the ages of three to five. In gene therapy, researchers insert normal genes into cells that have missing or defective genes in order to correct genetic disorders.
Experimental Studies on Germinal Localization (1904), by Edmund B. Wilson
At the turn of the twentieth century, Edmund B. Wilson
performed experiments to show where germinal
matter was located in molluscs. At Columbia University in New York City,
New York, Wilson studied what causes cells to differentiate during
development. In 1904 he conducted his experiments on molluscs, and he modified the
theory about the location of germinal matter in the succeeding years. Wilson and others modified the
theory of germinal localization to accommodate results that showed
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.
Leo Loeb (1869-1959)
Leo Loeb developed an experimental approach to studying cancer and pioneered techniques for tissue culture and in vitro tissue transplantation which impacted early-to-mid twentieth century experimental embryology. Loeb received his medical degree from the University of Zurich in 1897. As part of his doctorate, he completed a thesis on the outcomes of tissue transplantation in guinea pigs. Loeb's thesis inspired a life-long interest in tissue transplantation.
Dizhou Tong (1902-1979)
Dizhou Tong, also called Ti Chou Tung, studied marine animals and helped introduce and organize experimental embryology in China during the twentieth century. He introduced cellular nuclear transfer technology to the Chinese biological community, developed methods to clone organisms from many marine species, and investigated the role of cytoplasm in early development. Tong's administrative and scientific leadership in the fields of marine, cellular, and developmental biology contributed to China's experimental embryology research programs.
ABO Blood Type Identification and Forensic Science (1900-1960)
The use of blood in forensic analysis is a method for identifying individuals suspected of committing some kinds of crimes. Paul Uhlenhuth and Karl Landsteiner, two scientists working separately in Germany in the early twentieth century, showed that there are differences in blood between individuals. Uhlenhuth developed a technique to identify the existence of antibodies, and Landsteiner and his students showed that humans had distinctly different blood types called A, B, AB, and O.
Subject: Theories, Legal, Technologies
"Interspecific Chimeras in Mammals: Successful Production of Live Chimeras Between Mus musculus and Mus caroli" (1980), by Janet Rossant and William I. Frels
In 1980 Janet Rossant and William I. Frels published their paper, "Interspecific Chimeras in Mammals: Successful Production of Live Chimeras Between Mus musculus and Mus caroli," in Science. Their experiment involved the first successful creation of interspecific mammalian chimeras. Mammalian chimeras are valuable for studying early embryonic development. However, in earlier studies, clonal analysis was restricted by the lack of a cell marker, present at all times, that makes a distinction between the two parental cell types in situ.
Theophilus Shickel Painter (1889-1969)
Theophilus Shickel Painter studied the structure and
function of chromosomes in the US during in the early to mid-twentieth century. Painter worked at
the University of Texas at Austin in Austin, Texas. In the 1920s
and 1930s, Painter studied the chromosomes of the salivary gland
giant chromosomes of the fruit fly (Drosophila
melanogaster), with Hermann J. Muller. Muller and Painter
studied the ability of X-rays to cause changes in the chromosomes
of fruit flies. Painter also studied chromosomes in mammals.
Harry Hamilton Laughlin (1880-1943)
Harry Hamilton Laughlin helped lead the eugenics
movement in the United States during the early twentieth century.
The US eugenics movement of the early twentieth century sought to
reform the genetic composition of the United States population through
sterilization and other restrictive reproductive measures. Laughlin
worked as superintendent and assistant director of the Eugenics
Research Office (ERO) at Cold Spring Harbor Laboratory in Cold
Spring Harbor, New York, alongside director Charles Davenport.
Subject: People, Reproduction
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.
Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Gene
The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene was identified in 1989 by geneticist Lap-Chee Tsui and his research team as the gene associated with cystic fibrosis (CF). Tsui's research pinpointed the gene, some mutations to which cause CF, and it revealed the underlying disease mechanism. The CFTR gene encodes a protein in the cell membrane in epithelial tissues and affects multiple organ systems in the human body. Mutations in the CFTR gene cause dysfunctional regulation of cell electrolytes and water content.
Subject: Disorders, Reproduction
Alexis Carrel's Tissue Culture Techniques
Alexis Carrel, the prominent French surgeon, biologist, and 1912 Nobel Prize laureate for Physiology or Medicine, was one of the pioneers in developing and modifying tissue culture techniques. The publicized work of Carrel and his associates at the Rockefeller Institute established the practice of long-term tissue culture for a wide variety of cells. At the same time, some aspects of their work complicated the operational procedures of tissue culture.