Search

Displaying 1 - 25 of 309 items.

Pages

“Use of reproductive technology for sex selection for nonmedical reasons” (2015), by the Ethics Committee of the American Society for Reproductive Medicine

In June 2015, the Ethics Committee of the American Society for Reproductive Medicine, or ASRM, published “Use of reproductive technology for sex selection for nonmedical reasons” in Fertility and Sterility. In the report, the Committee presents arguments for and against the use of reproductive technology for sex selection for any reason besides avoiding sex-linked disorders, or genetic disorders that only affect a particular sex.

Format: Articles

Subject: Publications

Thomas Henry Huxley (1825-1895)

In nineteenth century Great Britain, Thomas Henry Huxley proposed connections between the development of organisms and their evolutionary histories, critiqued previously held concepts of homology, and promoted Charles Darwin's theory of evolution. Many called him Darwin's Bulldog. Huxley helped professionalize and redefine British science. He wrote about philosophy, religion, and social issues, and researched and theorized in many biological fields.

Format: Articles

Subject: People

"The Cell-Theory" (1853), by Thomas Henry Huxley

The Cell-Theory was written by Thomas Henry Huxley in Britain and published in 1853 by The British and Foreign Medico-Chirurgical Review. The twenty-two page article reviews twelve works on cell theory, including those in Germany by Caspar Friedrich Wolff in the eighteenth century and by Karl Ernst von Baer in the nineteenth century. Huxley spends much of The Cell-Theory on a cell theory proposed in the late 1830s by Matthias Schleiden and Theodor Schwann in Germany.

Format: Articles

Subject: Publications

Thomas Raphael Verny (1936– )

During the twentieth century, Thomas Raphael Verny studied the way that environment affects a developing fetus’s character and psychological development. Verny studied the concept of memory before birth and covered both the prenatal and perinatal periods, meaning the time the fetus is in the womb and the weeks immediately before or after birth, respectively. During those times, Verny claimed that patterns of maternal attitudes and experiences, such as affection and stress-related emotions, impact the development of the child.

Format: Articles

Subject: People

Alfred Henry Sturtevant (1891–1970)

Alfred Henry Sturtevant studied heredity in fruit flies in the US throughout the twentieth century. From 1910 to 1928, Sturtevant worked in Thomas Hunt Morgan’s research lab in New York City, New York. Sturtevant, Morgan, and other researchers established that chromosomes play a role in the inheritance of traits. In 1913, as an undergraduate, Sturtevant created one of the earliest genetic maps of a fruit fly chromosome, which showed the relative positions of genes along the chromosome.

Format: Articles

Subject: People

"The linear arrangement of six sex-linked factors in drosophila, as shown by their mode of association” (1913), by Alfred Henry Sturtevant

In 1913, Alfred Henry Sturtevant published the results of experiments in which he showed how genes are arranged along a chromosome. Sturtevant performed those experiments as an undergraduate at Columbia University, in New York, New York, under the guidance of Nobel laureate Thomas Hunt Morgan. Sturtevant studied heredity using Drosophila, the common fruit fly. In his experiments, Sturtevant determined the relative positions of six genetic factors on a fly’s chromosome by creating a process called gene mapping.

Format: Articles

Subject: Experiments, Publications

“Sex Limited Inheritance in Drosophila” (1910), by Thomas Hunt Morgan

In 1910, Thomas Hunt Morgan performed an experiment at Columbia University, in New York City, New York, that helped identify the role chromosomes play in heredity. That year, Morgan was breeding Drosophila, or fruit flies. After observing thousands of fruit fly offspring with red eyes, he obtained one that had white eyes. Morgan began breeding the white-eyed mutant fly and found that in one generation of flies, the trait was only present in males.

Format: Articles

Subject: Experiments, Publications

Henry Havelock Ellis (1859-1939)

Henry Havelock Ellis was born on 2 February 1859 at Croydon in Surrey, England, to Susannah Wheatley Ellis and Edward Peppen Ellis, a sea captain. A psychologist, essayist, and physician, he is best known for his contributions to the study of human sexuality and his support of sex education and women's rights. Ellis 's work catalyzed the revolution against repressive Victorian views of sexuality.

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

Mesoderm

Mesoderm is one of the three germ layers, groups of cells that interact early during the embryonic life of animals and from which organs and tissues form. As organs form, a process called organogenesis, mesoderm interacts with endoderm and ectoderm to give rise to the digestive tract, the heart and skeletal muscles, red blood cells, and the tubules of the kidneys, as well as a type of connective tissue called mesenchyme. All animals that have only one plane of symmetry through the body, called bilateral symmetry, form three germ layers.

Format: Articles

Subject: Processes

Germ Layers

A germ layer is a group of cells in an embryo that interact with each other as the embryo develops and contribute to the formation of all organs and tissues. All animals, except perhaps sponges, form two or three germ layers. The germ layers develop early in embryonic life, through the process of gastrulation. During gastrulation, a hollow cluster of cells called a blastula reorganizes into two primary germ layers: an inner layer, called endoderm, and an outer layer, called ectoderm.

Format: Articles

Subject: Theories, Processes

Thomas Hunt Morgan (1866-1945)

Although best known for his work with the fruit fly, for which he earned a Nobel Prize and the title "The Father of Genetics," Thomas Hunt Morgan's contributions to biology reach far beyond genetics. His research explored questions in embryology, regeneration, evolution, and heredity, using a variety of approaches.

Format: Articles

Subject: People

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

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

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

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

Henry Morgentaler (1923-2013)

Henry Morgentaler was a physician who performed abortions, acted as a reproductive rights activist, and advocated for legal access to abortions in Canada during the twentieth century. In 1969, he opened his first abortion clinic in Canada and participated in the legal/court case of R v. Morgentaler (1988), which led Canada to decriminalize abortion. Morgentaler helped establish legal access to abortions for women in Canada and advocated for the protection of women's reproductive choices under the law.

Format: Articles

Subject: People

“A Linkage Between DNA Markers on the X Chromosome and Male Sexual Orientation” (1993), by Dean H. Hamer and Charles A. Thomas.

In 1993, Dean H. Hamer and colleagues in the US published results from their research that indicated that men with speicifc genes were more likely to be homosexual than were men without those genes. The study hypothesized that some X chromosomes contain a gene, Xq28, that increases the likelihood of an individual to be homosexual. Prior to those results, researchers had argued that the cause of homosexuality was environmental and that homosexuality could be altered or reversed. Hamer’s research suggested a possible genetic cause of homosexuality.

Format: Articles

Subject: Experiments

Keith Henry Stockman Campbell (1954-2012)

Keith Henry Stockman Campbell studied embryo growth and cell differentiation during the twentieth and twenty-first centuries in the UK. In 1995, Campbell and his scientific team used cells grown and differentiated in a laboratory to clone sheep for the first time. They named these two sheep Megan and Morag. Campbell and his team also cloned a sheep from adult cells in 1996, which they named Dolly. Dolly was the first mammal cloned from specialized adult (somatic) cells with the technique of somatic cell nuclear transfer (SCNT).

Format: Articles

Subject: People

St. George Jackson Mivart (1827-1900)

St. George Jackson Mivart studied animals and worked in England during the nineteenth century. He also proposed a theory of organismal development that he called individuation, and he critiqued Charles Darwin's argument for evolution by natural selection. His work on prosimians, a group of primates excluding apes and monkeys, helped scientists better investigate the Primate group.

Format: Articles

Subject: People

Marshall Henry Klaus (1927–2017)

Marshall Henry Klaus was a scientist and pediatrician who studied maternal-infant bonding in the twentieth century in the United States. Maternal-infant bonding is the psychological and chemical attachment between mother and infant. Klaus cofounded DONA International, an organization that trains birthing aides, called doulas, to provide physical and emotional support to laboring mothers. He also studied the differences between the layouts and quality of care provided in nurseries and birthing centers in different countries and compared them to those found in the United States.

Format: Articles

Subject: People

Edward Donnall Thomas (1920-2012)

Edward Donnall Thomas, an American physician and scientist, gained recognition in the scientific community for conducting the first bone marrow transplant, a pioneering form of hematopoietic stem cell transplantation (HSCT). Bone marrow transplants are considered to be the first successful example of tissue engineering, a field within regenerative medicine that uses hematopoietic stem cells (HSCs) as a vehicle for treatment. Prior to Thomas's groundbreaking work, most blood-borne diseases, including certain inherited and autoimmune diseases, were considered lethal.

Format: Articles

Subject: People

St. Thomas Aquinas (c. 1225-1274)

Widely known as a key contributor to the Roman Catholic Church's body of doctrine, St. Thomas Aquinas also published an opinion on the moral status of embryos and fetuses that seems contradictory to the Catholic Church's current standpoint on the matter. Born in Naples, Italy, around 1225 (scholars debate the exact year of many of his life events) to wealthy nobility, Thomas Aquinas quickly proved himself a pious and astute scholar with an insatiable desire for logic and understanding.

Format: Articles

Subject: People, Religion

Stazione Zoologica Anton Dohrn, Naples, Italy

The Stazione Zoologica Anton Dohrn (Anton Dohrn Zoological Station) is a public research institute focusing on biology and biodiversity. Hereafter called the Station, it was founded in Naples, Italy, in 1872 by Anton Dohrn. The type of research conducted at the Station has varied since it was created, though initial research focused on embryology. At the turn of the twentieth century, researchers at the Station established the sea urchin (Echinoidea) as a model organism for embryological research.

Format: Articles

Subject: Organizations, People, Places

Karl Ernst von Baer's Laws of Embryology

In 1828, while working at the University of Konigsberg in Konigsberg, Germany Karl Ernst von Baer proposed four laws of animal development, which came to be called von Baer's laws of embryology. With these laws, von Baer described the development (ontogeny) of animal embryos while also critiquing popular theories of animal development at the time.

Format: Articles

Subject: Theories

Pages