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Displaying 151 - 175 of 817 items.

"A Series of Normal Stages in the Development of the Chick Embryo" (1951), by Viktor Hamburger and Howard L. Hamilton

The developmental stages of the chick embryo were examined by Viktor Hamburger and Howard L. Hamilton in "A Series of Normal Stages in the Development of the Chick Embryo," published in the Journal of Morphology in 1951. These stages were published to standardize the development of the chick based on varying laboratory conditions and genetic differences. The stages Hamburger and Hamilton assigned were determined by the visible features of the chick embryo.

Format: Articles

Subject: Experiments

The Discovery of Fetal Alcohol Syndrome

The term Fetal Alcohol Syndrome (FAS) was first published in 1973 in an article published in the British medical journal The Lancet. In that article, a group of pediatricians and psychiatrists at the University of Washington Medical School helped to define the morphological defects and developmental delays that can affect children born to alcoholic mothers. Those observations include pre- and post-natal growth deficiencies, minor facial abnormalities, and damage to the developing brain that can result in behavioral, learning, and cognitive abnormalities.

Format: Articles

Subject: Disorders, Reproduction

The Game of Life, by John Horton Conway

The Game of Life, or just Life, is a one-person game that was created by the English mathematician John Horton Conway in the late 1960s. It is a simple representation of birth, death, development, and evolution in a population of living organisms, such as bacteria. Martin Gardner popularized the Game of Life by writing two articles for his column "Mathematical Games" in the journal Scientific American in 1970 and 1971. There exist several websites that provide the Game of Life as a download or as an online game.

Format: Articles

Subject: Technologies

Paul Kammerer's Experiments on the Midwife Toad (1905-1910)

In the first decade of the twentieth century, Paul Kammerer, a zoologist working at the Vivarium in Vienna, Austria, conducted research on developmental mechanisms, including a series of breeding experiments on toads (Alytes obstetricans). Kammerer claimed that his results demonstrated that organisms could transmit acquired characteristics to their offspring.

Format: Articles

Subject: Experiments

Evangelium Vitae (1995), by Pope John Paul II

The encyclical entitled "Evangelium Vitae," meaning "The Gospel of Life," was promulgated on 25 March 1995 by Pope John Paul II in Rome, Italy. The document was written to reiterate the view of the Roman Catholic Church on the value of life and to warn against violating the sanctity of life. The document focuses on right to life issues including abortion, birth control, and euthanasia, but also touches on other concepts relevant to embryology, such as contraception, in vitro fertilization, sterilization, embryonic stem cell research, and fetal experimentation.

Format: Articles

Subject: Religion, Reproduction

Eugen Steinach (1861–1944)

Eugen Steinach researched sex hormones and their effects on mammals in the late nineteenth and early twentieth centuries in Europe. He experimented on rats by removing their testicles and implanting them elsewhere in their bodies, and he found that the testes interstitial cells produce male sex hormones. He developed the Steinach Rejuvenation Procedure, which he claimed could rejuvenate men by increasing their production of sex hormones. Steinach’s work on female sex hormones and on ovarian extracts led to the development of the first standardized injectable estrogen.

Format: Articles

Subject: People

Charles Otis Whitman (1842-1910)

Charles Otis Whitman was an extremely curious and driven researcher who was not content to limit himself to one field of expertise. Among the fields of study to which he made significant contributions were: embryology; morphology, or the form of living organisms and the relationships between their structures; natural history; and behavior.

Format: Articles

Subject: People

Curt Jacob Stern (1902-1981)

Curt Jacob Stern studied radiation and chromosomes in humans and fruit flies in the United States during the twentieth century. He researched the mechanisms of inheritance and of mitosis, or the process in which the chromosomes in the nucleus of a single cell, called the parent cell, split into identical sets and yield two cells, called daughter cells. Stern worked on the Drosophila melanogaster fruit fly, and he provided early evidence that chromosomes exchange genetic material during cellular reproduction.

Format: Articles

Subject: People

Francis Maitland Balfour (1851-1882)

During the 1870s and early 1880s, the British morphologist Francis Maitland Balfour contributed in important ways to the budding field of evolutionary embryology, especially through his comparative embryological approach to uncovering ancestral relationships between groups. As developmental biologist and historian Brian Hall has observed, the field of evolutionary embryology in the nineteenth century was the historical ancestor of modern-day evolutionary developmental biology.

Format: Articles

Subject: People

Calvin Bridges’ Experiments on Nondisjunction as Evidence for the Chromosome Theory of Heredity (1913-1916)

From 1913 to 1916, Calvin Bridges performed experiments that indicated genes are found on chromosomes. His experiments were a part of his doctoral thesis advised by Thomas Hunt Morgan in New York, New York. In his experiments, Bridges studied Drosophila, the common fruit fly, and by doing so showed that a process called nondisjunction caused chromosomes, under some circumstances, to fail to separate when forming sperm and egg cells. Nondisjunction, as described by Bridges, caused sperm or egg cells to contain abnormal amounts of chromosomes.

Format: Articles

Subject: Experiments, Publications

"The Developmental Capacity of Nuclei Taken from Intestinal Epithelium Cells of Feeding Tadpoles" (1962), by John B. Gurdon

In 1962 researcher John Bertrand Gurdon at the University of Oxford in Oxford, England, conducted a series of experiments on the developmental capacity of nuclei taken from intestinal epithelium cells of feeding tadpoles. In the experiments, Gurdon conducted nuclear transplantation, or cloning, of differentiated cells, or cells that have already specialized to become one cell type or another, in tadpoles. Gurdon's experiment showed that differentiated adult cells could be induced to an undifferentiated state, where they could once again become multiple cell types.

Format: Articles

Subject: Experiments

Beatrice Mintz (1921- )

Beatrice Mintz is a brilliant researcher who has developed techniques essential for many aspects of research on mouse development. She produced the first successful mouse chimeras and meticulously characterized their traits. She has worked with various cancers and produced viable mice from the cells of a teratoma. Mintz participated in the development of transgenic mice by the incorporation of foreign DNA into a mouse genome.

Format: Articles

Subject: People

Samuel Randall Detwiler (1890-1957)

Samuel Randall Detwiler was an embryologist who studied neural development in embryos and vertebrate retinas. He discovered evidence for the relationship between somites and spinal ganglia, that transplanted limbs can be controlled by foreign ganglia, and the plasticity of ganglia in response to limb transplantations. He also extensively studied vertebrate retinas during and after embryonic development.

Format: Articles

Subject: People

Thesis: Visualizing the Embryo: Establishing Procedures for Digital Image Production with the Embryo Project

Until 2013, the Embryo Project Encyclopedia had not presented images in articles due to the fact that there was no formal protocol for developing images at that time. I have created an image style guide that outlines the basic steps of creating and submitting an image that can complement an Embryo Project article and can enhance a reader’s understanding of the discussed concept. In creating this style guide, I investigate similar protocols used by other scientific journals and medical professionals.

Format: Essays and Theses

Subject: Outreach

"Adenocarcinoma of the Vagina: Association of Maternal Stilbestrol Therapy with Tumor Appearance in Young Women" (1971), by Arthur L. Herbst, et al.

Published in 1971, Adenocarcinoma of the Vagina: Association of Maternal Stilbestrol Therapy with Tumor Appearance in Young Women, by Arthurs L. Herbst and colleagues, was the first piece of literature connecting maternal use of the drug diethylstilbestrol (DES), also called stilbestrol, with the development of a rare and severe form of vaginal cancer in young women. Diethylstilbestrol was later classified as an endocrine disruptor, a substance that disrupts the hormonal function of the body in those exposed to it during development or later in life.

Format: Articles

Subject: Publications

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

The Marine Biological Laboratory

The Marine Biological Laboratory (MBL) was founded in 1888 in Woods Hole, Massachusetts. Woods Hole was already the site for the government 's US Fish Commission Laboratory directed by Spencer Fullerton Baird, and it seemed like the obvious place to add an independent research laboratory that would draw individual scientific investigators along with students and instructors for courses.

Format: Articles

Subject: Organizations

Sir D'Arcy Wentworth Thompson (1860-1948)

Known by many for his wide-reaching interests and keen thinking, D'Arcy Wentworth Thompson was one of Britain's leading scientific academics in the first few decades of the twentieth century. A prodigious author, Thompson published some 300 papers, books, and articles in the biological sciences, classics, oceanography, and mathematics. He was a famous lecturer and conversationalist-a true "scholar-naturalist," as his daughter wrote in her biography of her father.

Format: Articles

Subject: People

"Behavioral Thermoregulation by Turtle Embryos" (2011), by Wei-Guo Du, Bo Zhao, Ye Chen, and Richard Shine

In "Behavioral Thermoregulation by Turtle Embryos," published in Proceedings of the National Academy of Sciences in April, 2011, Wei-Guo Du, Bo Zhao, Ye Chen, and Richard Shine report that turtle embryos can move towards warmer temperatures within the egg when presented with a small, 0.8 degrees Celsius gradient. This behavioral thermoregulation may benefit the embryo's fitness by accelerating the rate of development enough to decrease the incubation period by up to four and a half days. Embryos are generally thought to have little control over their surroundings.

Format: Articles

Subject: Publications

Paul Kammerer's Experiments on Salamanders (1903-1912)

In the early twentieth century, Paul Kammerer conducted a series of experiments to demonstrate that organisms could transmit characteristics acquired in their lifetimes to their offspring. In his 1809 publication, zoologist Jean-Baptiste Lamarck had hypothesized that living beings can inherit features their parents or ancestors acquired throughout life. By breeding salamanders, as well as frogs and other organisms, Kammerer tested Lamarck's hypothesis in an attempt to provide evidence for Lamarck's theory of the inheritance of acquired characteristics.

Format: Articles

Subject: Experiments

Neurocristopathies

Neurocristopathies are a class of pathologies in vertebrates,
including humans, that result from abnormal expression, migration,
differentiation, or death of neural crest cells (NCCs) during embryonic development. NCCs are cells
derived from the embryonic cellular structure called the neural crest.
Abnormal NCCs can cause a neurocristopathy by chemically affecting the
development of the non-NCC tissues around them. They can also affect the
development of NCC tissues, causing defective migration or

Format: Articles

Subject: Theories

Charles Darwin's Theory of Pangenesis

In 1868 in England, Charles Darwin proposed his pangenesis theory to describe the units of inheritance between parents and offspring and the processes by which those units control development in offspring. Darwin coined the concept of gemmules, which he said referred to hypothesized minute particles of inheritance thrown off by all cells of the body. The theory suggested that an organism's environment could modify the gemmules in any parts of the body, and that these modified gemmules would congregate in the reproductive organs of parents to be passed on to their offspring.

Format: Articles

Subject: Theories

Beadle and Ephrussi’s Technique to Transplant Optic Discs between Fruit Fly Larvae

In 1935, George Beadle and Boris Ephrussi developed a technique to transplant optic discs between fruit fly larvae. They developed it while at the California Institute of Technology in Pasedena, California. Optic discs are tissues from which the adult eyes develop. Beadle and Ephrussi used their technique to study the development of the eye and eye pigment. (1) The experimenter dissects a donor larva, which is in the third instar stage of development, and removes the optic disc (colored red) with a micropipette.

Format: Graphics

Subject: Technologies, Experiments, Organisms

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.

Format: Articles

Subject: People

Stem Cells

According to the US National Institutes of Health (NIH), the standard American source on stem cell research, three characteristics of stem cells differentiate them from other cell types: (1) they are unspecialized cells that (2) divide for long periods, renewing themselves and (3) can give rise to specialized cells, such as muscle and skin cells, under particular physiological and experimental conditions. When allowed to grow in particular environments, stem cells divide many times. This ability to proliferate can yield millions of stem cells over several months.

Format: Articles

Subject: Processes