Embryo Project Encyclopedia

Leonard Hayflick studied the processes by which cells age during the twentieth and twenty-first centuries in the United States. In 1961 at the Wistar Institute in the US, Hayflick researched a phenomenon later called the Hayflick Limit, or the claim that normal human cells can only divide forty to sixty times before they cannot divide any further. Researchers later found that the cause of the Hayflick Limit is the shortening of telomeres, or portions of DNA at the ends of chromosomes that slowly degrade as cells replicate. Hayflick used his research on normal embryonic cells to develop a vaccine for polio, and from HayflickÕs published directions, scientists developed vaccines for rubella, rabies, adenovirus, measles, chickenpox and shingles.

In the 1936 case United States v. One Package of Japanese Pessaries, the US Court of Appeals for the Second Circuit in New York City, New York, confirmed that physicians had the right to distribute contraceptives to patients for medical purposes. In January 1933, US Customs confiscated a package of contraceptives imported from Japan by US physician Hannah Stone. They claimed that the package violated section 305 of the Tariff Act of 1930, which, like the 1873 anti-obscenity Comstock Act, granted the US government authority to seize contraceptive materials imported into the country or sent through the mail. The court ruled that US Customs was not justified in confiscating the package and ordered its return to Stone. United States v. One Package exempted physicians from the restrictions surrounding the distribution of contraceptives and contributed to the subsequent dismantling of the Comstock Act in later court cases.

Anthony Comstock was a US postal inspector and politician who advocated for the suppression of obscenity and vice throughout the late nineteenth century and early twentieth century. Comstock considered any sexually explicit material like pornography and literature related to birth control and abortion as obscene. In 1873, Comstock lobbied US Congress to pass an anti-obscenity law titled An Act for the Suppression of Trade in, and Circulation of, Obscene Literature and Articles of Immoral Use, also called the Comstock Act. The law penalized individuals for sending material classified as obscene through the US postal services, which Comstock, as a special agent of the United States Post Office, could enforce. Comstock’s role in passing and enforcing the Comstock Act influenced the social and political restriction of birth control, hindering women’s access to contraceptives.

In the 1983 case City of Akron v. Akron Center for Reproductive Health the US Supreme Court ruled that certain requirements of the city of Akron’s “Regulation on Abortion” ordinance violated women’s rights to abortions. Despite the legalization of abortion in the 1973, with the US Supreme Court case Roe v. Wade, individual states passed legislation regulating certain aspects of abortion. The city of Akron, Ohio, passed legislation in 1978 that regulated when and where abortions could be conducted, the consent process leading up to abortions, and the disposal of fetal remains after abortions. In a six to three ruling, the Court argued provisions of the city of Akron’s ordinance were unconstitutional. The Court’s opinion in City of Akron v. Akron Center for Reproductive Health reaffirmed the ruling in Roe v. Wade that states could not unduly restrict women’s access to abortions.

What Every Girl Should Know was published in 1916 in New York City, New York, as a compilation of articles written by Margaret Sanger from 1912 to 1913. The original articles appeared in the newspaper New York Call, under the tile “What Every Girl Should Know.” The articles, which are organized into chapters and individual parts in the book, describe sex education, human reproduction, and sexually transmitted infections. Sanger, a nurse and social activist, published What Every Girl Should Know during a time in which US federal and state obscenity laws regulated the circulation of literature related to sex. What Every Girl Should Know flouted those laws, helping people to learn about sex education and reproductive health in the US during the early twentieth century.

What Every Mother Should Know was published in 1914 in New York City, New York, as a compilation of newspaper articles written by Margaret Sanger in 1911. The series of articles informed parents about how to teach their children about reproduction and it appeared in the newspaper New York Call. In 1911, the newspaper series was published as a book, with several subsequent editions appearing later. In What Every Mother Should Know, Sanger emphasizes starting education on reproduction early and honestly answering children’s questions. The book acted as a resource for parents and urged readers to be less fearful of approaching the topic with their children. What Every Mother Should Know provided information to the public about sex education and reproductive health, which was scarce during the early twentieth century.

Margaret Higgins Sanger advocated for birth control in the United States and Europe during the late nineteenth and early twentieth centuries. Although people used contraceptives prior to the twentieth century, in the US the 1873 Comstock Act made the distribution of information relating to the use of contraceptives illegal, and similar state-level Comstock laws also classified discussion and dissemination of contraceptives as illegal. Sanger helped to repeal the Comstock Act and similar laws so that women could legally use contraceptives to control their fertility and the sizes of their families. In 1916, Sanger opened the first birth control clinic in the US in New York City, New York. Later in life, Sanger formed several advocacy organizations that promoted access to contraception, including the Planned Parenthood Federation of America. Sanger's advocacy increased women's access to contraception and helped change the United States' social and legal perceptions of birth control.

Leonard Hayflick in the US during the early 1960s showed that normal populations of embryonic cells divide a finite number of times. He published his results as 'The Limited In Vitro Lifetime of Human Diploid Cell Strains' in 1964. Hayflick performed the experiment with WI-38 fetal lung cells, named after the Wistar Institute, in Philadelphia, Pennsylvania, where Hayflick worked. Frank MacFarlane Burnet, later called the limit in capacity for cellular division the Hayflick Limit in 1974. In the experiment, Hayflick refuted Alexis Carrel's hypothesis that cells could be transplanted and multiplied indefinitely from a single parent cell line.

Telomeres are structures at the ends of DNA strands that get longer in the DNA of sperm cells as males age. That phenomenon is different for most other types of cells, for which telomeres get shorter as organisms age. In 1992, scientists showed that telomere length (TL) in sperm increases with age in contrast to most cell of most other types. Telomeres are the protective caps at the end of DNA strands that preserve chromosomal integrity and contribute to DNA length and stability. In most cells, telomeres shorten with each cell division due to incomplete replication, though the enzyme telomerase functions in some cell lines that undergo repetitive divisions to replenish any lost length and to prevent degradation. Cells, and therefore organisms, with short telomeres are more susceptible to mutations and genetic diseases. While TL increases in a subset of sperm cells and longer telomeres may prevent early disintegration of DNA, it may also prevent natural mechanisms of apoptosis, or cell death, from occurring in abnormal sperm.

Annie Dodge Wauneka, a member of the Navajo Tribal Council in Window Rock, Arizona, from 1951 to 1978, advocated for improved lifestyle, disease prevention, and access to medical knowledge in the Navajo Indian Reservation, later renamed the Navajo Nation. Wauneka served as chair of the Health and Welfare Committee of the Navajo Tribal Council and as a member of the US Surgeon General’s Advisory Committee on Indian Health. Wauneka advocated for initiatives aimed at promoting education, preventing tuberculosis, and reducing the infant mortality rate. In 1963, she was awarded the Presidential Medal of Freedom. Wauneka’s initiatives to educate mothers about child health and increase hospital births reduced infant mortality rates in the Navajo Indian Reservation during the twentieth century.