Embryo Project Encyclopedia

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. Darwin's theory of pangenesis gradually lost popularity in the 1890s when biologists increasingly abandoned the theory of inheritance of acquired characteristics (IAC), on which the pangenesis theory partially relied. Around the turn of the twentieth century, biologists replaced the theory of pangenesis with germ plasm theory and then with chromosomal theories of inheritance, and they replaced the concept of gemmules with that of genes.

The US 2nd Circuit Court of Appeals' 1984 decision United States v. University Hospital, State University Hospital of New York at Stony Brook set a significant precedent for affirming parental privilege to make medical decisions for handicapped newborns, while limiting the ability of the federal government to intervene. The ruling stemmed from the 1983 case involving an infant born with severe physical and mental congenital defects; the infant was only identified as Baby Jane Doe. After her parents opted against corrective surgery for some of her deformities, Baby Jane Doe became the epicenter of a national right-to-life debate that had been previously sparked one year prior with the case of Baby Doe, an Indiana infant born with similarly severe handicaps.

Green fluorescent protein (GFP) is a protein in the jellyfish Aequorea Victoria that exhibits green fluorescence when exposed to light. The protein has 238 amino acids, three of them (Numbers 65 to 67) form a structure that emits visible green fluorescent light. In the jellyfish, GFP interacts with another protein, called aequorin, which emits blue light when added with calcium. Biologists use GFP to study cells in embryos and fetuses during developmental processes.

Golden Rice was engineered from normal rice by Ingo Potrykus and Peter Beyer in the 1990s to help improve human health. Golden Rice has an engineered multi-gene biochemical pathway in its genome. This pathway produces beta-carotene, a molecule that becomes vitamin A when metabolized by humans. Ingo Potrykus worked at the Swiss Federal Institute of Technology in Zurich, Switzerland, and Peter Beyer worked at University of Freiburg, in Freiburg, Germany. The US Rockefeller Foundation supported their collaboration. The scientists and their collaborators first succeeded in expressing beta-carotene in rice in 1999, and they published the results in 2000. Since then, scientists have improved Golden Rice through laboratory and field trials, but as of 2013 no countries have grown it commercially. Golden Rice is a technology that intersects scientific and ethical debates that extend beyond a grain of rice.

The Baby Doe Rules represent the first attempt by the US government to directly intervene in treatment options for neonates born with congenital defects. The name of the rule comes from the controversial 1982 case of a Bloomington, Indiana infant Baby Doe, a name coined by the media. The Baby Doe Rules mandate that, as a requirement for federal funding, hospitals and physicians must provide maximal care to any impaired infant, unless select exceptions are met. If a physician or parent chooses to withhold full treatment when the exceptions are not met, they are liable for medical neglect. After a prolonged legal battle, President Ronald Reagan signed the law on 9 October 1984 as an amendment to the Child Abuse Prevention and Treatment Act (CAPTA) of 1974. Since then, the Baby Doe Rules have influenced both the parents' right to make medical decisions for their child and the way laws can affect treatment options in the US.

Friedrich Leopold August Weismann published Das
Keimplasma: eine Theorie der Vererbung (The Germ-Plasm: a
Theory of Heredity, hereafter The Germ-Plasm) while
working at the University of Freiburg in Freiburg, Germany in 1892.
William N. Parker, a professor in the University College of South
Wales and Monmouthshire in Cardiff, UK, translated The
Germ-Plasm into English in 1893. In The Germ-Plasm,
Weismann proposed a theory of heredity based on the concept of the
germ plasm, a substance in the germ cell that carries hereditary information. The
Germ-Plasm compiled Weismann's theoretical work and analyses of
other biologists' experimental work in the 1880s, and it provided a
framework to study development, evolution and heredity. Weismann
anticipated that the germ-plasm theory would enable researchers to
investigate the functions and material of hereditary substances.

The French flag model represents how embryonic cells receive and respond to genetic information and subsequently differentiate into patterns. Created by Lewis Wolpert in the late 1960s, the model uses the French tricolor flag as visual representation to explain how embryonic cells can interpret genetic code to create the same pattern even when certain pieces of the embryo are removed. Wolpert's model has provided crucial theoretical framework for investigating universal mechanisms of pattern formation during development.

Dell Publishing in New York City, New York, published Lennart Nilsson's A Child Is Born in 1966. The book was a translation of the Swedish version called Ett barn blir till, published in 1965. It sold over a million copies in its first edition, and has translations in twelve languages. Nilsson, a photojournalist, documented a nine-month human pregnancy using pictures and accompanying text written by doctors Axel Ingelman-Sundberg, Claes Wirsen and translated by Britt and Claes Wirsen and Annabelle MacMillian. Critics lauded A Child Is Born for its photographs taken in utero of a developing fetus. Furthermore, the work received additional praise for what many described as simple and scientifically accurate explanations of complicated processes during development.

August Friedrich Leopold Weismann studied how the traits of organisms developed and evolved in a variety of organisms, mostly insects and aquatic animals, in Germany in the late nineteenth and early twentieth centuries. Weismann proposed the theory of the continuity of germ-plasm, a theory of heredity. Weismann postulated that germ-plasm was the hereditary material in cells, and parents transmitted to their offspring only the germ-plasm present in germ-cells (sperm and egg cells) rather than somatic or body cells. Weismann also promoted Charles Darwin's 1859 theory of the evolution of species. Weismann argued that only changes to the germ cells, and not body cells, could be inherited, a theory that influenced theories of heredity throughout later centuries.

Christiane Nusslein-Volhard studied how genes control embryonic development in flies and in fish in Europe during the twentieth and twenty-first centuries. In the 1970s, Nusslein-Volhard focused her career on studying the genetic control of development in the fruit fly Drosophila melanogaster. In 1988, Nusslein-Volhard identified the first described morphogen, a protein coded by the gene bicoid in flies. In 1995, along with Eric F. Wieschaus and Edward B. Lewis, she received the Nobel Prize in Physiology or Medicine for the discovery of genes that establish the body plan and segmentation in Drosophila. Nusslein-Volhard also investigated the genetic control of embryonic development to zebrafish, further generalizing her findings and helping establishing zebrafish as a model organism for studies of vertebrate development.