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Epigenetic Landscape

The epigenetic landscape is a concept representing embryonic development. It was proposed by Conrad Hal Waddington to illustrate the various developmental pathways a cell might take toward differentiation. The epigenetic landscape integrates the connected concepts of competence, induction, and regulative abilities of the genes into a single model designed to explain cellular differentiation, a long standing problem in embryology.

Format: Articles

Subject: Theories

Temperature-Dependent Sex Determination in Reptiles

The sex of a reptile embryo partly results from the production of sex hormones during development, and one process to produce those hormones depends on the temperature of the embryo's environment. The production of sex hormones can result solely from genetics or from genetics in combination with the influence of environmental factors. In genotypic sex determination, also called genetic or chromosomal sex determination, an organism's genes determine which hormones are produced.

Format: Articles

Subject: Experiments

The Cell in Development and Inheritance (1900), by Edmund Beecher Wilson

The Cell in Development and Inheritance, by Edmund Beecher Wilson, provided a textbook introduction to cell biology for generations of biologists in the twentieth century. In his book, Wilson integrated information about development, inheritance, chromosomes, organelles, and the structure and functions of cells. First published in 1896, the book started with 371 pages, grew to 483 pages in the second edition that appeared in 1900, and expanded to 1,231 pages by the third and final edition in 1925.

Format: Articles

Subject: Publications

The Inheritance of Acquired Characteristics (1924), by Paul Kammerer

The Inheritance of Acquired Characteristics is a book published in 1924, written by Paul Kammerer, who studied developmental biology in Vienna, Austria, in the early twentieth century. The Inheritance of Acquired Characteristics summarizes Kammerer's experiments, and explains their significance. In his book, Kammerer aims to explain how offspring inherit traits from their parents. Some scholars criticized Kammerer's reports and interpretations, arguing that they were inaccurate and misleading, while others supported Kammerer's work.

Format: Articles

Subject: Publications, Theories

Human Evolution Inferred from Tooth Growth and Development

To study human evolution, researchers sometimes use microstructures found in human teeth and their knowledge of the processes by which those structures grow. Human fetusus begin to develop teeth in utero. As teeth grow, they form a hard outer substance, called enamel, through a process called amelogenesis. During amelogenesis, incremental layers of enamel form in a Circadian rhythm. This rhythmic deposition leaves the enamel with microstructures, called cross-striations and striae of Retzius, which have a regular periodicity.

Format: Articles

Subject: Theories

Edward Drinker Cope's Law of Acceleration of Growth

The Law of Acceleration of Growth is a theory proposed by Edward Drinker Cope in the US during the nineteenth century. Cope developed it in an attempt to explain the evolution of genera by appealing to changes in the developmental timelines of organisms. Cope proposed this law as an additional theory to natural selection.

Format: Articles

Subject: Theories

Neural Crest

Early in the process of development, vertebrate embryos develop a fold on the neural plate where the neural and epidermal ectoderms meet, called the neural crest. The neural crest produces neural crest cells (NCCs), which become multiple different cell types and contribute to tissues and organs as an embryo develops. A few of the organs and tissues include peripheral and enteric (gastrointestinal) neurons and glia, pigment cells, cartilage and bone of the cranium and face, and smooth muscle.

Format: Articles

Subject: Theories

Francois Jacob (1920-2013)

Francois Jacob studied in
bacteria and bacteriophages at the Institut Pasteur in Paris, France,
in the second half of the twentieth century. In 1965, Jacob won the
Nobel Prize in Physiology or Medicine with Andre M. Lwoff and
Jacques L. Monod for their work on the genetic control of enzyme
synthesis. Jacob studied how genes control and regulate metabolic
enzymes in the bacterium Escherichia
coli (E. coli) and in lysogenic
bacterial systems. He contributed to theories of transcriptional gene

Format: Articles

Subject: People

"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

Spemann-Mangold Organizer

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.

Format: Articles

Subject: Processes

General Embryological Information Service, published annually by the Hubrecht Laboratory, 1949-1981

The General Embryological Information Service (GEIS) was an annual report published by the Hubrecht Laboratory in Utrecht, The Netherlands from 1949 to 1981 that disseminated contemporary research information to developmental biologists. The purpose of the annual report was to catalog the names, addresses, and associated research of every developmental biologist in the world. Pieter Nieuwkoop edited each issue from 1949 until 1964, when Job Faber began assisting Nieuwkoop. Bert Z. Salome joined the editing team in 1968 before Nieuwkoop ceased editing duties in 1971.

Format: Articles

Subject: Organizations

Trisomy 21 (Down Syndrome)

As of 2022, Trisomy 21 is the most common type of trisomy, or a condition where the person has three instead of the normal two copies of one of the chromosomes. Trisomy occurs when abnormal cell division takes place leading to an extra copy of a chromosome. That extra copy of chromosome 21 results in a congenital disorder called Down syndrome, which is characterized by a cluster of specific traits including intellectual disabilities, atypical facial appearance, and a high risk of heart disease.

Format: Articles

Subject: Reproduction, Disorders, Ethics

The Biological Bulletin

From 1886 to 1889 Charles Otis Whitman was director of the Allis Lake Laboratory in Milwaukee, Wisconsin. The lab was established by Edward Phelps Allis, Jr. to provide a place for biological research separate from a university setting and a place where an independent scholar like Allis himself could work. Allis had hired Whitman as an instructor to establish the lab, direct it, and lead a research program there. The lab lasted for eight years, attracted several researchers, and the papers that came out of the lab included a focus on embryology.

Format: Articles

Subject: Publications

The Notch Signaling Pathway in Embryogenesis

The Notch signaling pathway is a mechanism in animals by which adjacent cells communicate with each other, conveying spatial information and genetic instructions for the animal's development. All multicellular animals utilize Notch signaling, which contributes to the formation, growth, and development of embryos (embryogenesis). Notch signaling also contributes to the differentiation of embryonic cells into various types of cells into various types of cells, such as neurons.

Format: Articles

Subject: Processes

Revive & Restore’s Woolly Mammoth Revival Project

In 2015, Revive & Restore launched the Woolly Mammoth Revival Project with a goal of engineering a creature with genes from the woolly mammoth and introducing it back into the tundra to combat climate change. Revive & Restore is a nonprofit in California that uses genome editing technologies to enhance conservation efforts in sometimes controversial ways.

Format: Articles

Subject: Theories, Technologies, Organizations, Ethics

Amphioxus, and the Mosaic Theory of Development (1893), by Edmund Beecher Wilson

Edmund Beecher Wilson experimented with Amphioxus (Branchiostoma) embryos in 1892 to identify what caused their cells to differentiate into new types of cells during the process of development. Wilson shook apart the cells at early stages of embryonic development, and he observed the development of the isolated cells. He observed that in the normal development of Amphioxus, all three main types of symmetry, or cleavage patterns observed in embryos, could be found. Wilson proposed a hypothesis that reformed the Mosaic Theory associated with Wilhelm Roux in Germany.

Format: Articles

Subject: Experiments

"Developmental Capacity of Nuclei Transplanted from Keratinized Skin Cells of Adult Frogs" (1975), by John Gurdon, Ronald Laskey, and O. Raymond Reeves

In 1975 John Gurdon, Ronald Laskey, and O. Raymond Reeves published "Developmental Capacity of Nuclei Transplanted from Keratinized Skin Cells of Adult Frogs," in the Journal of Embryology and Experimental Morphology. Their article was the capstone of a series of experiments performed by Gurdon during his time at Oxford and Cambridge, using the frog species Xenopus laevis. Gurdon's first experiment in 1958 showed that the nuclei of Xenopus cells maintained their ability to direct normal development when transplanted.

Format: Articles

Subject: Experiments, Publications

Form and Function (1916), by Edward Stuart Russell

In 1916, at the age of twenty-nine, Edward Stuart Russell published his first major work, Form and Function: a Contribution to the History of Animal Morphology. This book has maintained wide readership among scientists and historians since its initial publication, and today is generally recognized as the first modern, sustained study of the history of morphology. In particular, Form and Function incorporates an extensive theoretical analysis of the relationship between embryological studies and comparative morphology in the nineteenth century.

Format: Articles

Subject: Publications

Berthold Karl Hölldobler (1936– )

Berthold Karl Hölldobler studied social insects like ants in Europe and the US during the twentieth and early twenty-first century. He focused on the social behavior of ants, the evolutionary origins of social insects, and the way ants use chemicals to communicate with each other. Hölldobler’s research reached popular audiences through his co-authored Pulitzer Prize winning book The Ants and through an award winning nature documentary called Ameisen: Die heimliche Weltmacht (Ants: Nature’s Secret Power).

Format: Articles

National Association for Down Syndrome (1960–)

The National Association for Down Syndrome, or NADS, is an organization that was founded in 1960 by Kathryn McGee in Chicago, Illinois, to support people with Down syndrome and their families in improving their quality of life. Originally named the Mongoloid Developmental Council, NADS is one of the oldest organizations serving people with Down syndrome and their families in the United States. According to NADS, Down syndrome is a genetic condition that occurs in one in every seven hundred ninety-two people and that causes delays in physical and intellectual development.

Format: Articles

Subject: Disorders, Organizations, People, Ethics

Victor Ambros (1953-)

Victor Ambros is a professor of molecular medicine at the University of Massachusetts Medical School, and he discovered the first microRNA (miRNA) in 1993. Ambros researched the genetic control of developmental timing in the nematode worm Caenorhabditis elegans and he helped describe gene function and regulation during the worm’s development and embryogenesis. His discovery of miRNA marked the beginning of research into a form of genetic regulation found throughout diverse life forms from plants to humans. Ambros is a central figure in the miRNA and C.

Format: Articles

Subject: People

Julia Barlow Platt (1857-1935)

Julia Barlow Platt studied neural crests in animal embryos and became involved in politics in the US during the nineteenth and twentieth centuries. She researched how body and head segments formed in chicks (Gallus gallus) and spiny dogfish (Squalus acanthias). Platt observed that in the mudpuppy (Necturus maculosus), the coordinated migration of neural crest cells in the embryo produced parts of the nervous system, bones, and connective tissues in the head.

Format: Articles

Subject: People

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

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.

Format: Articles

Subject: People

August Antonius Rauber (1841-1917)

August Antonius Rauber was an embryologist and anatomist who examined gastrulation in avian embryos. He examined the formation of the blastopore, epiblast, and primitive streak during chick development. Subsequent researchers have further studied Rauber's findings, which has led to new discoveries in embryology and developmental biology.

Format: Articles

Subject: People