Embryo Project Encyclopedia Articles

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. Regardless of the presence of two or three layers, endoderm is always the inner-most layer. Endoderm forms the epithelium-- a type of tissue in which the cells are tightly linked together to form sheets-- that lines the primitive gut. From this epithelial lining of the primitive gut, organs like the digestive tract, liver, pancreas, and lungs develop.

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. Huxley made several methodological contributions to both invertebrate and vertebrate embryology and development, and he helped shape the extra-scientific discourse for these fields.

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.

In the 1989 case Webster v. Reproductive Health Services, the
US Supreme Court upheld the constitutionality of a Missouri law regulating abortion care. The
Missouri law prohibited the use of public facilities, employees, or
funds to provide abortion counseling or services. The law also placed restrictions on physicians who provided
abortions. A group of physicians affected by the law challenged the
constitutionality of certain sections of it. The US federal district
court that first heard the case ruled many of the challenged sections of
the law unconstitutional. The Missouri attorney general then appealed
the case to an US federal appeals court and eventually to the US Supreme
Court in Washington, D.C. In a five to four decision, the US Supreme
Court overturned the decisions of the lower federal courts, ruling that
it was constitutional to prohibit public funds, facilities, and
employees from providing abortion care. In doing so, the Supreme
Court upheld a state law that limited women’s access to abortions
and established a precedent that states could apply restrictions to
abortion care.

The Family Planning Services and Public Research Act of 1970, often called Title X Family Planning Program, is a US federal law that provides federal funding for family planning services to low income or uninsured families. The US federal government passed the law, Public Law 91-572, in 1970 as an amendment to the Public Health Services Act of 1944. The Act created the Office of Population Affairs (OPA) under the Secretary of Health, Education, and Welfare (here called the Secretary). Through the Act, the OPA and the Secretary provide resources and policy advice to the US government on health issues. The OPA also issue grants and formed contracts with public and nonprofit organizations to assist in the establishment and operation of voluntary family planning services. The Act helped to extend reproductive health services to low income individuals and to individuals who otherwise struggle to get such services.

Margaret Goldwater advocated for birth control and reproductive rights in the United States during the twentieth century. Goldwater was a socialite and philanthropist and was married to Barry Goldwater, US Senator from Arizona. She spent much of her life working to further the women's reproductive rights movement, which sought to expand women's legal, social, and physical access to reproductive healthcare, including contraception and abortions. Goldwater, with guidance from birth control activist Margaret Sanger, helped establish the second birth control clinic in Arizona, the Mother's Health Clinic in Phoenix, Arizona. She conducted large fundraising events and authored articles in local newspapers on the need for contraceptives and family planning. Goldwater's advocacy helped launch and sustain The Mother's Health Clinic, which became the largest provider of women's reproductive healthcare in Arizona, and it later became Planned Parenthood of Central and Northern Arizona.

Barry Morris Goldwater was a Republican Arizona Senator and US presidential candidate in the twentieth-century whose policies supported the women's reproductive rights movement. Goldwater, a businessman and Air Force reservist, transitioned into politics in the 1950s. He helped align popular support for a conservative Republican Party in the 1960s. Throughout his life, he worked to maintain personal liberty and to limit governmental intrusion into citizens' private lives. Goldwater, influenced by his wife Margaret (Peggy) Goldwater, supported women's rights to abortions. Goldwater's advocacy and support for reproductive rights assisted in the foundation of the Planned Parenthood chapter in Phoenix, Arizona, and for national policies promoting birth control and abortion rights.

The 1973 case Nelson v. Planned Parenthood Center of Tucson established the legality of abortion in Arizona. The Arizona Court of Appeals ruled that the Arizona Revised Statutes 13-211, 13-212, and 13-213, collectively called the Arizona abortion statutes, were unconstitutional. The statutes had made illegal receiving, providing, or advertising abortions. After the Arizona Appeals Court heard the case, it decided that the Arizona abortion statutes were constitutional. However, two weeks later the US Supreme Court decided in Roe v. Wade (1973) that abortion was constitutional at the federal level. The Arizona court followed the precedent set by the US Supreme Court and amended its decision to rule that the Arizona abortion statutes were unconstitutional. Afterwards, Planned Parenthood, other family planning clinics, and hospitals were legally allowed in Arizona to advertise, discuss, and offer abortions as an option to their patients.

In the 2013 case Isaacson v. Horne, the US Court of Appeals in the Ninth Circuit ruled that Arizona House Bill (HB) 2036, which prohibited abortions after twenty weeks of gestation, was unconstitutional. The Arizona State Legislature passed the law in 2012, which was then challenged by three physicians who filed a lawsuit against the state, arguing that the law violated women's constitutionally protected rights to abortions, rights that may only be infringed once fetuses are viable outside of the womb. In hearing the case, the Ninth Circuit US Court of Appeals relied on the precedent set by the US Supreme Court in Roe v. Wade (1973) that ruled that states could not constitutionality prohibit abortions prior to fetal viability at twenty-four weeks. The case Isaacson v. Horne strengthened the precedent in Arizona that laws prohibiting abortion prior to fetal viability are unconstitutional, and it upheld women's rights to decide to terminate their pregnancies prior to fetal viability.

In 1893, Julia Barlow Platt published her research on the origins of cartilage in the developing head of the common mudpuppy (Necturus maculosus) embryo. The mudpuppy is an aquatic salamander commonly used by embryologists because its large embryonic cells and nuclei are easy to see. Platt followed the paths of cells in developing mudpuppy embryos to see how embryonic cells migrated during the formation of the head. With her research, Platt challenged then current theories about germ layers, the types of cells in an early embryo that develop into adult cells. In most organisms' development, three types of germ layers are responsible for the formation of tissues and organs. The outermost layer is called ectoderm, the middle layer mesoderm, and the innermost layer endoderm, although Platt called it entoderm. Platt's research provided a basis for scientists to clarify the destination or function of the germ layers in vertebrates' development.