Embryo Project Encyclopedia

Tooth enamel contains relics of its formation process, in the form of microstructures, which indicate the incremental way in which it forms. These microstructures, called cross-striations and striae of Retzius, develop as enamel-forming cells called ameloblasts, whcih cyclically deposit enamel on developing teeth in accordance with two different biological clocks. Cross-striations result from a twenty-four hour cycle, called a Circadian rhythm, in the enamel deposition process, while striae of Retzius have a longer periodicity. Unlike other tissues, enamel does not remodel after it forms, leaving those microstructures intact after deposition. Cross-striations and striae of Retzius thus provide evidence of the timing and processes of tooth development, and they indicate how organisms in a lineage differently grow and develop across generations. Researchers have examined those microstructures to investigate human evolution.

The principal work of St. Thomas Aquinas, the Summa Theologica is divided into three parts and is designed to instruct both beginners and experts in all matters of Christian Truth. It discusses topics central to Christian morality, ethics, law, and the life of Christ, providing philosophical and theological solutions to common arguments and questions surrounding the Christian faith. The views presented in this body of writing are currently upheld in large part by the modern doctrines of the Roman Catholic Church. Interesting references to and insights on ensoulment and embryology, as well as other topics discussed in Summa Theologica, indicate a strong Aristotelian and Augustinian influence.

Among his myriad scientific and artistic contributions, Leonardo da Vinci's work in embryology was groundbreaking. He observed and diagramed the previously undemonstrated position of the fetus in the womb with detailed accompanying annotations of his observations. Leonardo was highly paranoid of plagiarism and wrote all of his notes in mirror-like handwriting laden with his own codes, making his writing difficult to discern and delaying its impact. Although he carried out his studies in embryology from 1510-1512, it was not until the 1900s that his work was popularized among the scientific community. Leonardo's embryological annotations found in the third volume of his private notebooks represent his notable contributions to and explanations of human development and embryology.

In 1914 Albert Niemann, a German pediatrician who primarily studied infant metabolism, published a description of an Ashkenazi Jewish infant with jaundice, nervous system and brain impairments, swollen lymph nodes (lymphadenopathy), and an enlarged liver and spleen (hepatosplenomegaly). He reported that these anatomical disturbances resulted in the premature death of the child at the age of eighteen months. After extensively studying the abnormal characteristics of the infant, Niemann came to the conclusion that the disease was a variant of Gaucher's disease. Gaucher's disease, described by the French dermatologist Philippe Gaucher in 1882, is a lipid storage disorder resulting in an excessive accumulation of lipids in the spleen, kidneys, liver, lungs, bone marrow, and brain. Niemann was able to connect the infant's disease to Gaucher's disease because it displayed similar symptoms: a noticeable accumulation of fatty substances in the brain, liver, and spleen.

Historically the exact age of human embryo specimens has long perplexed embryologists. With the menstrual history of the mother often unknown or not exact, and the premenstrual and postmenstrual phases varying considerably among women, age sometimes came down to a best guess based on the weight and size of the embryo. Wilhelm His was one of the first to write comparative descriptions of human embryos in the late 1800s. Soon afterward, Franklin P. Mall, the first director of the Carnegie Institution of Washington's (CIW) Department of Embryology, expanded upon His' work. Mall's first efforts were to place embryos into stages based on menstrual ages and body length. This method ran into problems however when it became apparent that obtaining menstrual ages was often impossible or simply too inaccurate even if the information could be obtained from the women who carried the embryos. Mall decided instead to look for patterns among embryos to come up with some type of staging system whereby embryo age could be more accurately determined.

The Planned Parenthood Committee of Phoenix was established in 1942 to expand Arizona women's access to family planning resources. The Planned Parenthood Committee of Phoenix was formed through the merging of The Mother's Health Clinic in Phoenix, Arizona, with the national Planned Parenthood Federation of America. The clinic was primarily based within the Phoenix Memorial Hospital campus but expanded to other locations in the late 1960s. Until it became Planned Parenthood of Central and Northern Arizona in 1978, the Planned Parenthood Committee of Phoenix provided Arizona women with contraception, initially in the form of diaphragms and spermicide, and later including the birth control pill. It also provided educational information on relationships, sex, contraception, and infertility.

The San Diego Zoo Institute for Conservation Research (SDZICR) in San Diego, California, is a research organization that works to generate, use, and share information for the conservation of wildlife and their habitats. In 1975, Kurt Benirschke, a researcher at the University of California, San Diego (UCSD) who studied human and animal reproduction, and Charles Bieler, the director of the San Diego Zoo, collaborated to form the Center for Reproduction of Endangered Species (CRES). In 2009, the San Diego Zoo announced the creation of SDZICR, which expanded and replaced CRES, to provide central organization and management of scientific programs at the San Diego Zoo. By 2004, Allison Alberts was the director of research and for more than a decade oversaw the SDZICR's many research initiatives, including the collection and storage of genetic and reproductive information of rare and endangered animal and plant species.

Walter Edward Dandy studied abnormalities in the developing human brain in the United States in the twentieth century. He collaborated with pediatrician Kenneth Blackfan to provide the first clinical description of Dandy-Walker Syndrome, a congenital brain malformation in which the medial part of the brain, called the cerebellar vermis, is absent. Dandy also described the circulation of cerebral spinal fluid, the clear, watery fluid that surrounds and cushions the brain and spinal cord. That description led Dandy to examine how the impeded flow of cerebral spinal fluid caused congenital hydrocephalus, which occurs when fluid accumulates in the brain causes it to swell. Dandy discovered brain anomalies that primarily develop during embryonic development, and his work helped to detect brain abnormalities.

The Chicago Women’s Liberation Union, hereafter Union or CWLU, was a feminist union that operated in Chicago, Illinois, from 1969 to 1977 and was the first and largest union, at the time of its operation, focused on women’s issues. The Union organized women with the self-proclaimed collective goal of achieving liberation from sexism and inequality. Within the larger CWLU, smaller groups and chapters formed to address issues such as abortion, rape, child care, and reproductive health, among others. During CWLU’s eight years of operation, the activists circulated petitions, held demonstrations, and visited high schools to raise public awareness of women’s issues. The CWLU created educational opportunities for women in response to apparent sexism in the US and connected them to social groups to further the women’s liberation movement and women’s reproductive health awareness in the United States.

The Boston Women’s Health Book Collective was a women’s health organization headquartered in Boston, Massachusetts, that published the informational book Our Bodies Ourselves, which sold over 4.5 million copies. Initially called the Doctor’s Group, the Collective formed in response to the insufficiency of women-specific health information during the late 1960s and early 1970s. Members of the organization participated in the women’s liberation movement in Boston, Massachusetts, and conducted research on women’s health using resources such as medical textbooks. They collectively created an original publication surrounding women’s health concerns and offered educational courses for women to learn more about their bodies and to share their experiences. The Boston Women’s Health Book Collective, later called Our Bodies Ourselves, expanded access to women’s health information throughout the world with their publications, courses, and outreach.