Search

Displaying 476 - 500 of 542 items.

Petr Alekseevich Kropotkin (1842-1921)

Petr Kropotkin proposed the theory of Pleistocene ice age, alternative theories of evolution based on embryology, and he advocated anarchist and communist social doctrines in Europe during the nineteenth and twentieth centuries. He traveled in eastern Siberia and Manchuria from 1863 until 1867, and his subsequent publications about that area's geography became authoritative until the middle of the twentieth century.

Format: Articles

Subject: People

Teratogens

Teratogens are substances that may produce physical or functional defects in the human embryo or fetus after the pregnant woman is exposed to the substance. Alcohol and cocaine are examples of such substances. Exposure to the teratogen affects the fetus or embryo in a variety of ways, such as the duration of exposure, the amount of teratogenic substance, and the stage of development the embryo or fetus is in during the exposure.

Format: Articles

Subject: Disorders

A History of Embryology (1959), by Joseph Needham

In 1931 embryologist and historian Joseph Needham published a well-received three-volume treatise titled Chemical Embryology. The first four chapters from this work were delivered as lectures on Speculation, Observation, and Experiment, as Illustrated by the History of Embryology at the University of London. The same lectures were later released as a book published in 1934 titled A History of Embryology.

Format: Articles

Subject: Publications

Fetal Surgery

Fetal surgeries are a range of medical interventions performed in utero on the developing fetus of a pregnant woman to treat a number of congenital abnormalities. The first documented fetal surgical procedure occurred in 1963 in Auckland, New Zealand when A. William Liley treated fetal hemolytic anemia, or Rh disease, with a blood transfusion.

Format: Articles

Subject: Disorders, Ethics, Reproduction

Carl Richard Moore (1892-1955)

Carl Richard Moore was a professor and researcher at the University of Chicago in Chicago, Illinois who studied sex hormones in animals from 1916 until his death in 1955. Moore focused on the role of hormones on sex differentiation in offspring, the optimal conditions for sperm production, and the effects of vasectomy or testicular implants on male sex hormone production. Moore's experiments to create hermaphrodites in the laboratory contributed to the theory of a feedback loop between the pituitary and fetal gonadal hormones to control sex differentiation.

Format: Articles

Subject: People

Frank Rattray Lillie's Study of Freemartins (1914-1920)

Frank Rattray Lillie's research on freemartins from 1914 to 1920 in the US led to the theory that hormones partly caused for sex differentiation in mammals. Although sometimes applied to sheep, goats, and pigs, the term freemartin most often refers to a sterile cow that has external female genitalia and internal male gonads and was born with a normal male twin.

Format: Articles

Subject: 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

Mary-Claire King (1946– )

Mary-Claire King studied genetics in the US in the twenty-first century. King identified two genes associated with the occurrence of breast cancer, breast cancer 1 (BRCA1) and breast cancer 2 (BRCA2). King showed that mutated BRCA1 and BRCA2 genes cause two types of reproductive cancer, breast and ovarian cancer. Because of King’s discovery, doctors can screen women for the inheritance of mutated BRCA1 and BRCA2 genes to evaluate their risks for breast and ovarian cancer.

Format: Articles

Subject: People

"On the Replication of Desoxyribonucleic Acid (DNA)" (1954), by Max Delbruck

In 1954 Max Delbruck published On the Replication of Desoxyribonucleic Acid (DNA) to question the semi-conservative DNA replication mechanism proposed that James Watson and Francis Crick had proposed in 1953. In his article published in the Proceedings of the National Academy of Sciences, Delbrück offers an alternative DNA replication mechanism, later called dispersive replication. Unlike other articles before it, On the Replication presents ways to experimentally test different DNA replication theories.

Format: Articles

Subject: Publications

What Every Girl Should Know (1916), by Margaret Sanger

What Every Girl Should Know was published in 1916 in New York City, New York, as a compilation of articles written by Margaret Sanger from 1912 to 1913. The original articles appeared in the newspaper New York Call, under the tile “What Every Girl Should Know.” The articles, which are organized into chapters and individual parts in the book, describe sex education, human reproduction, and sexually transmitted infections.

Format: Articles

Subject: Publications

Equilibrium Density Gradient Centrifugation in Cesium Chloride Solutions Developed by Matthew Meselson and Franklin Stahl

Matthew Meselson, Franklin Stahl, and Jerome Vinograd, developed cesium chloride, or CsCl, density gradient centrifugation in the 1950s at the California Institute of Technology, or Caltech, in Pasadena, California. Density gradient centrifugation enables scientists to separate substances based on size, shape, and density. Meselson and Stahl invented a specific type of density gradient centrifugation, called isopycnic centrifugation that used a solution of cesium chloride to separate DNA molecules based on density alone.

Format: Articles

Alan Mathison Turing (1912-1954)

Alan Mathison Turing was a British mathematician and computer scientist who lived in the early twentieth century. Among important contributions in the field of mathematics, computer science, and philosophy, he developed a mathematical model of morphogenesis. This model describing biological growth became fundamental for research on the process of embryo development.

Format: Articles

Subject: People

"On the Nature of the Process of Fertilization and the Artificial Production of Normal Larvae (Plutei) From the Unfertilized Eggs of the Sea Urchin" (1899), by Jacques Loeb

Jacques Loeb developed procedures to make embryos from unfertilized sea urchin eggs in 1899. Loeb called the procedures "artificial parthenogenesis," and he introduced them and his results in "On the Nature of the Process of Fertilization and the Artificial Production of Norma Larvae (Plutei) from the Unfertilized Eggs of the Sea Urchin" in an 1899 issue of The American Journal of Physiology. In 1900 Loeb elaborated on his experiments.

Format: Articles

Subject: Experiments

Circulatory Changes at Birth

When placental mammals are born their circulatory systems undergo radical changes as the newborns are prepared for independent life. The lungs are engaged, becoming the primary source of fresh oxygen, replacing the placental barrier as a means for blood-gas exchange.

Format: Articles

Subject: Processes

Ethics of Designer Babies

A designer baby is a baby genetically engineered in vitro for specially selected traits, which can vary from lowered disease-risk to gender selection. Before the advent of genetic engineering and in vitro fertilization (IVF), designer babies were primarily a science fiction concept. However, the rapid advancement of technology before and after the turn of the twenty-first century makes designer babies an increasingly real possibility.

Format: Articles

Subject: Ethics, Reproduction

Effects of Prenatal Alcohol Exposure on Basal Ganglia Development

Prenatal exposure to alcohol (ethanol) in human and animal models results in a range of alcohol-induced developmental defects. In humans, those collective birth defects are called Fetal Alcohol Spectrum Disorders, with the most severe manifestation being Fetal Alcohol Syndrome (FAS). FAS is defined by pre- and post-natal growth retardation, minor facial abnormalities, and deficiencies in the central nervous system (CNS). The basal ganglia, one of the central nervous system components, are affected by exposure to ethanol during development.

Format: Articles

Subject: Disorders, Reproduction

Artificial Parthenogenesis and Fertilization (1913), by Jacques Loeb

Jacques Loeb is best known for his embryological work investigating parthenogenesis in invertebrates. Artificial Parthenogenesis and Fertilization is a revised and English-translated work from his earlier book, Die chemische Entwicklungserregung des tierischen Eies (1900). Artificial Parthenogenesis describes Loeb's many and varied methodical experiments to initiate egg development without fertilization by sperm. As is true with much of science, some of Loeb's experiments were successful and many were not.

Format: Articles

Subject: Publications

The Organism as a Whole: From a Physicochemical Viewpoint (1916), by Jacques Loeb

Jacques Loeb published The Organism as a Whole: From a Physicochemical Viewpoint in 1916. Loeb's goal for the book was to refute the claim that physics and chemistry were powerless to completely explain whole organisms and their seemingly goal-oriented component processes. Loeb used his new account of science and scientific explanation, marshaling evidence from his embryological researches, to show that physicochemical biology completely and correctly explained whole organisms and their component processes.

Format: Articles

Subject: Publications

Radioimmunoassay

Radioimmunoassay (RIA) is a technique in which researchers use radioactive isotopes as traceable tags to quantify specific biochemical substances from blood samples. Rosalyn Yalow and Solomon Berson developed the method in the 1950s while working at the Bronx Veterans Administration (VA) Hospital in New York City, New York. RIA requires small samples of blood, yet it is extremely sensitive to minute quantities of biological molecules within the sample. The use of RIA improved the accuracy of many kinds of medical diagnoses, and it influenced hormone and immune research around the world.

Format: Articles

Subject: Technologies

Hamburger-Hamilton Staging Series (1951)

In 1951 Viktor Hamburger and Howard Hamilton created an embryonic staging series from a combination of photographs and drawings from other researchers. The Hamburger-Hamilton stages are a sequence of images depicting 46 chronological stages in chick development. The images begin with a fertilized egg and end with a fully developed chick. The Hamburger-Hamilton staging series was produced in order to replace a previous chick staging series created in 1900. The earlier attempt lacked specific details and staged the chick embryo by using only morphological characteristics.

Format: Articles

Subject: Processes

Pre- and Post-natal Growth Deficiencies and Fetal Alcohol Syndrome

Maternal consumption of alcohol (ethanol) during pregnancy can inhibit prenatal growth, resulting in fetuses that are small for gestational age. Those prenatal growth deficiencies can have lasting consequences for early childhood development and are often reflected by low weight and stature. Those alcohol-induced pre- and post-natal growth deficiencies ("failure to thrive") are among the abnormal developmental criteria used to identify Fetal Alcohol Syndrome (FAS). FAS is characterized by minor facial abnormalities and deficiencies of the central nervous system as well.

Format: Articles

Subject: Disorders

William Harvey (1578-1657)

Renowned physician and scientist William Harvey is best known for his accurate description of how blood circulates through the body. While his published work on the circulation of blood is considered the most important of his academic life, Harvey also made significant contributions to embryology with the publication of his book Exercitationes de Generatione Animalium in 1651. In this book he established several theories that would set the stage for modern embryology and addressed many embryological issues including conception, embryogenesis, and spontaneous generation.

Format: Articles

Subject: People

De Formatione Ovi et Pulli (1621), by Girolamo Fabrici

The embryological treatise De formatione ovi et pulli (On the Formation of the Egg and of the Chick) was written by anatomist and embryologist Girolamo Fabrici and published in Padua posthumously in 1621. The book was edited by Joahannes Prevotius and is separated into two parts that describe Fabrici's observations and assumptions on embryology and combine the traditional knowledge of his predecessors with his own first-hand anatomical observations.

Format: Articles

Subject: Publications

Howard Wilber Jones Jr.

Howard Wilber Jones Jr. and his wife, Georgeanna Seegar Jones, developed a method of in vitro fertilization and helped create the first baby in the US using that method. Though the first in vitro baby was born in England in 1978, Jones and his wife's contribution allowed for the birth of Elizabeth Carr on 28 December 1981. Jones, a gynecologist and an obstetrician, researched human reproduction for most of his life.

Format: Articles

Subject: People, Reproduction

Anencephaly

Anencephaly is an open neural tube defect, meaning that part of the neural tube does not properly close or that it has reopened during early embryogenesis. An embryo with anencephaly develops without the top of the skull, but retains a partial skull, including the face. Anencephaly is one of the most common birth defects of the neural tube, occurring at a rate of approximately one in one thousand human pregnancies. The condition can be caused by environmental exposure to chemicals, dietary deficiencies, or genetic mutations.

Format: Articles

Subject: Disorders, Reproduction