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Nuclear Transplantation
Nuclear transplantation is a method in which the nucleus of a donor cell is relocated to a target cell that has had its nucleus removed (enucleated). Nuclear transplantation has allowed experimental embryologists to manipulate the development of an organism and to study the potential of the nucleus to direct development. Nuclear transplantation, as it was first called, was later referred to as somatic nuclear transfer or cloning.
Format: Articles
Subject: Processes
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
Biological Clocks and the Formation of Human Tooth Enamel
Tooth enamel contains relics of its formation process, in the form of microstructures, which indicate the incremental way in which it forms. These microstructures, called cross-striations and striae of Retzius, develop as enamel-forming cells called ameloblasts, whcih cyclically deposit enamel on developing teeth in accordance with two different biological clocks. Cross-striations result from a twenty-four hour cycle, called a Circadian rhythm, in the enamel deposition process, while striae of Retzius have a longer periodicity.
Format: Articles
Subject: 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
Embryos in Wax (2002), by Nick Hopwood
Embryos in Wax: Models from the Ziegler Studio is a history of embryo wax modeling written by science historian Nick Hopwood. Published by the Whipple Museum of the History of Science University of Cambridge and the Institute of the History of Medicine University of Bern, 2002, the book, like the wax models, helps exemplify the visual and material culture of science.
Format: Articles
Subject: Publications
Conjoined Twins
Conjoined twins are twins whose bodies are anatomically joined in utero. The degree to which the twins are attached can range from simple, involving skin and cartilage, to complex, including fusion of the skull(s), brain(s), or other vital organs. There are more than a dozen classifications of conjoined twins but what they all tend to have in common is the sharing of the chorion, placenta, and amniotic sac.
Format: Articles
Subject: Disorders, Reproduction
Twin-to-Twin Transfusion Syndrome
Twin-to-Twin Transfusion Syndrome (TTTS) is a rare placental disease that can occur at any time during pregnancy involving identical twins. TTTS occurs when there is an unequal distribution of placental blood vessels between fetuses, which leads to a disproportionate supply of blood delivered. This unequal allocation of blood leads to developmental problems in both fetuses that can range in severity depending on the type, direction, and number of interconnected blood vessels.
Format: Articles
Subject: Disorders, Reproduction
Multi-Fetal Pregnancy
In humans, multi-fetal pregnancy occurs when a mother carries more than one fetus during the pregnancy. The most common multi-fetal pregnancy is twins, but mothers have given birth to up to eight children (octuplets) from a single pregnancy. Multiple fetusus can result from the release of multiple eggs or multiple ovulations, the splitting of a single fertilized egg, and fertility treatments such as in vitro fertilization (IVF) which involves the insertion of many fertilized eggs into the mother's uterus.
Format: Articles
Subject: Processes, Reproduction
Patrick Christopher Steptoe (1913-1988)
Patrick Christopher Steptoe was a British gynecologist responsible for major advances in gynecology and reproductive technology. Throughout his career Steptoe promoted laparoscopy, a minimally invasive surgical technique that allows a view inside the abdominal cavity, successfully advancing its usefulness in gynecology. After partnering with embryologist Robert Edwards in 1966, the pair performed the first in vitro fertilization in humans.
Format: Articles
Subject: People, Reproduction
Effects of Prenatal Alcohol Exposure on Cardiac Development
A variety of developmental defects occur as a result of prenatal exposure to alcohol (ethanol) in utero. In humans, those defects are collectively classified as Fetal Alcohol Spectrum Disorders, with Fetal Alcohol Syndrome (FAS) representing the more severe defects. FAS is defined by pre- and post-natal growth retardation, minor facial abnormalities, and deficiencies in the central nervous system (CNS). In addition to those defects, prenatal exposure to alcohol impacts cardiogenesis, the developmental stage of heart formation.
Format: Articles
Subject: Disorders, Reproduction
Elizabeth Maplesden Ramsey (1906-1993)
Physician and pathologist Elizabeth Maplesden Ramsey was a member of the Carnegie Institution of Washington (CIW) for thirty-nine years. The affiliation began in 1934, when Ramsey discovered what was assumed to be the youngest-known embryo at the time, and donated it to CIW's massive embryo collection. After studying embryos, Ramsey focused her research on placental circulation in primates.
Format: Articles
Subject: People
Morphogenesis
The term morphogenesis generally refers to the processes by which order is created in the developing organism. This order is achieved as differentiated cells carefully organize into tissues, organs, organ systems, and ultimately the organism as a whole. Questions centered on morphogenesis have aimed to uncover the mechanisms responsible for this organization, and developmental biology textbooks have identified morphogenesis as one of the main challenges in the field. The concept of morphogenesis is intertwined with those of differentiation, growth, and reproduction.
Format: Articles
Subject: Processes
Hensen's Node
A node, or primitive knot, is an enlarged group of cells located in the anterior portion of the primitive streak in a developing gastrula. The node is the site where gastrulation, the formation of the three germ layers, first begins. The node determines and patterns the anterior-posterior axis of the embryo by directing the development of the chordamesoderm. The chordamesoderm is a specific type of mesoderm that will differentiate into the notochord, somites, and neural tube. Those structures will later form the vertebral column.
Format: Articles
Subject: Processes
Warren Harmon Lewis (1870-1964)
As one of the first to work at the Carnegie Institution of Washington Department of Embryology, Warren Harmon Lewis made a number of contributions to the field of embryology. In addition to his experimental discoveries on muscle development and the eye, Lewis also published and revised numerous works of scientific literature, including papers in the Carnegie Contributions to Embryology and five editions of Gray's Anatomy.
Format: Articles
Subject: People
Wilhelm His, Sr. (1831-1904)
Wilhelm His, Sr. was born on 9 July 1831 in Basel, Switzerland, to Katharina La Roche and Eduard His. He began his medical studies at Basel in 1849 and later transferred to the University of Bern during the winter semester of 1849-1850. A year later, His arrived at the University of Berlin, where he studied under Johannes Müller and Robert Remak. For his clinical training, His attended the University of Würzburg from 1852-1853.
Format: Articles
Subject: People
Wilhelm Roux (1850-1924)
Wilhelm Roux was a nineteenth-century experimental embryologist who was best known for pioneering Entwicklungsmechanik, or developmental mechanics. Roux was born in Jena, Germany, on 9 June 1850, the only son of Clotilde Baumbach and a university fencing master, F. A. Wilhelm Ludwig Roux. Roux described himself as an aloof child, but when he was fourteen he cultivated a passion for science that was encouraged by the director at Oberrealschule in Meiningen.
Format: Articles
Subject: People
"Experiments on Embryonic Induction III. A Note on Inductions by Chick Primitive Streak Transplanted to the Rabbit Embryo" (1934), by Conrad Hal Waddington
Conrad Hal Waddington's "Experiments on Embryonic Induction III," published in 1934 in the Journal of Experimental Biology, describes the discovery that the primitive streak induces the mammalian embryo. Waddington's hypothesis was that a transplanted primitive streak could induce neural tissue in the ectoderm of the rabbit embryo. The primitive streak defines the axis of an embryo and is capable of inducing the differentiation of various tissues in a developing embryo during gastrulation.
Format: Articles
Subject: Experiments
Organisers and Genes (1940), by Conrad Hal Waddington
Conrad Hal Waddington's Organisers and Genes, published in 1940, is a summary of available research and theoretical framework for many concepts related to tissue differentiation in the developing embryo. The book is composed of two main conceptual sections. The first section explores the action and nature of the organizer, while the second section delves into genes and their influence on development.
Format: Articles
Subject: Publications
Karl Freiherr von Rokitansky (1804–1878)
During the nineteenth century, Karl Freiherr von Rokitansky conducted research on the causes of disease by performing approximately 30,000 autopsies, a practice that many people opposed at the time. Rokitansky performed his research in pathology, or the study of disease, and morbid anatomy, or the study of dead bodies, in Vienna, then part of the Austrian Empire and later part of Austria.
Format: Articles
Subject: People
"Generation of Germline-Competent Induced Pluripotent Stem Cells" (2007), by Keisuke Okita, Tomoko Ichisaka, and Shinya Yamanaka
In the July 2007 issue of Nature, Keisuke Okita, Tomoko Ichisaka, and Shinya Yamanaka added to the new work on induced pluripotent stem cells (iPSCs) with their "Generation of Germline-Competent Induced Pluripotent Stem Cells" (henceforth abbreviated "Generation"). The authors begin the paper by noting their desire to find a method for inducing somatic cells of patients to return to a pluripotent state, a state from which the cell can differentiate into any type of tissue but cannot form an entire organism.
Format: Articles
Subject: Publications
"Alternative Sources of Human Pluripotent Stem Cells" (2005), by Leon Kass and the President’s Council on Bioethics
Human pluripotent stem cells are valued for their potential to form numerous specialized cells and for their longevity. In the US, where a portion of the population is opposed to destruction of human embryos to obtain stem cells, what avenues are open to scientists for obtaining pluripotent cells that do not offend the moral sensibilities of a significant number of citizens?
Format: Articles
Subject: Publications, Ethics
Priscilla White (1900–1989)
Priscilla White studied
the treatment of diabetes in mothers, pregnant women, and
children during the twentieth century in the US. White began
working with children with Type 1 diabetes in 1924 at Elliott
Proctor Joslin’s practice in Boston, Massachusetts. Type 1
diabetes is an incurable disease where the pancreas produces
little to no insulin. Insulin is a hormone that allows the body
to use sugar from food for energy and store sugars for future
use. Joslin and White co-authored many publications on children
Format: Articles
Subject: People
Harald zur Hausen (1936–)
Harald zur Hausen studied viruses and discovered that certain strains of the human papilloma virus (HPV), a sexually transmitted disease, can cause cervical cancer, in Europe during the twentieth and twenty-first centuries. Zur Hausen spent his research career identifying the viruses that cause diseases, particularly cancer-causing viruses (oncoviruses). He primarily focused on HPV and cervical cancer. Zur Hausen hypothesized that HPV was cancerous and discovered that two strains, HPV 16 and 18, caused cervical cancer.
Format: Articles
Subject: People
Estrogen and the Menstrual Cycle in Humans
Estrogen is the primary sex hormone in women and it functions during the reproductive menstrual cycle. Women have three major types of estrogen: estrone, estradiol, and estriol, which bind to and activate receptors within the body. Researchers discovered the three types of estrogen over a period of seven years, contributing to more detailed descriptions of the menstrual cycle. Each type of estrogen molecule contains a slightly different arrangement or number of atoms that in turn causes some of the estrogens to be more active than others.
Format: Articles
Subject: Theories, Reproduction
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