Embryo Project Encyclopedia Articles

The "Humanae Vitae," meaning "Of Human Life" and subtitled "On the Regulation of Birth," was an encyclical promulgated in Rome, Italy, on 25 July 1968 by Pope Paul VI. This encyclical defended and reiterated the Roman Catholic Church's stance on family planning and reproductive issues such as abortion, sterilization, and contraception. The document continues to have a controversial reputation today, as its statements regarding birth control strike many Catholics as unreasonable.

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.

Barbara McClintock conducted experiments on corn (Zea mays) in the United States in the mid-twentieth century to study the structure and function of the chromosomes in the cells. McClintock researched how genes combined in corn and proposed mechanisms for how those interactions are regulated. McClintock received the Nobel Prize in Physiology or Medicine in 1983, the first woman to win the prize without sharing it. McClintock won the award for her introduction of the concept of transposons, also called jumping genes. McClintock conceptualized some genetic material as not static in structure and order, but as subject to re-arrangement and may be altered during development.

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.

Arthur Earl Walker was a medical researcher and physician who studied the brain and neurosurgery in the United States during the twentieth century. Walker examined the connections of the thalamus to the rest of the brain and how the thalamus coordinates sensory signals. The thalamus is a cluster of nerve cells located between the two hemispheres of the brain and it is responsible for consciousness and sensory interpretation. While studying the thalamus, Walker noticed that cerebral spinal fluid, the clear fluid surrounding the brain and spinal cord, sometimes became obstructed in certain parts of the brain in infants. Scientists linked the cerebral spinal fluid obstruction with a congenital brain malformation, later called Dandy-Walker Syndrome. Walker's work on the brain and cerebral spinal fluid enabled early diagnosis and treatment for complications in the development of the brain.

Emmett McLoughlin wrote People's Padre: An Autobiography, based on his experiences as a Roman Catholic priest advocating for the health of people in Arizona. The Beacon Press in Boston, Massachusetts, published the autobiography in 1954. McLoughlin was a Franciscan Order Roman Catholic priest who advocated for public housing and healthcare for the poor and for minority groups in Phoenix, Arizona, during the mid twentieth century. The autobiography recounts McLoughlin's efforts in founding several community initiatives throughout Phoenix, including the St. Monica's Community Center, later renamed St. Pius X Catholic Church, the Phoenix housing projects, and St. Monica's Hospital, later renamed Phoenix Memorial Hospital. McLoughlin's autobiography discusses his advocacy for people to have greater access to maternity and prenatal healthcare, to testing and treatment for sexually transmitted infections, and to birth control in the Phoenix area.

De ovi mammalium et hominis genesi (On the Genesis of the Ovum of Mammals and of Men) is an 1827 pamphlet by Karl Ernst von Baer about the anatomical observation and description of the egg (ovum) of mammals, like dogs and humans. The pamphlet detailed evidence for the existence of the ovum at the beginning of the developmental process in mammals. Prior to von Baer's publication, there was much debate about how organisms develop, as some claimed that organisms grow from a corpuscular element already preformed in the body (preformationism), and others said that organisms developed from a fluid material undergoing a process of progressive formation (epigenesis). Researchers at the time struggled to observe the early stages of development, and those such as von Baer had to observe the phenomenon through microscopes and then provide interpretations of the phenomena they observed.

"Casti Connubii," a papal encyclical given by Pope Pius XI on 31 December 1930, served primarily as a reaffirmation and expansion of the issues discussed in Arcanum, an encyclical written by Pope Leo XIII. It was released to address new threats to marriage and conjugal unity, and indeed is translated "On Christian Marriage" or "On Chastity in Marriage." The document explores the meaning of Christian marriage and emphasizes its threefold purpose as borrowed from St. Augustine: to produce offspring, to grow in conjugal faith, and to show benefit from the sacrament. It begins by exploring the nature of marriage, followed by a discussion of its advantages for individuals and societies, erroneous but common beliefs about marriage, threats to pure marriage, and finally how to address them. Included in the threats to pure marriage is that of the growing popularity of contraception and abortive procedures, at which point Pope Pius XI elaborates on the Church' s statement that life begins at conception.

Aristotle studied developing organisms, among other things, in ancient Greece, and his writings shaped Western philosophy and natural science for greater than two thousand years. He spent much of his life in Greece and studied with Plato at Plato's Academy in Athens, where he later established his own school called the Lyceum. Aristotle wrote greater than 150 treatises on subjects ranging from aesthetics, politics, ethics, and natural philosophy, which include physics and biology. Less than fifty of Aristotle's treatises persisted into the twenty-first century. In natural philosophy, later called natural science, Aristotle established methods for investigation and reasoning and provided a theory on how embryos generate and develop. He originated the theory that an organism develops gradually from undifferentiated material, later called epigenesis.

Edmund Beecher Wilson in the US published An Atlas of Fertilization and Karyokinesis of the Ovum (hereafter called An Atlas) in 1895. The book presents photographs by photographer Edward Leaming that capture stages of fertilization, the fusion of sperm and egg and early development of sea urchin (Toxopneustes variegatus) ova, or egg cell. Prior to An Atlas, no one photographed of eggcell division in clear detail. Wilson obtained high quality images of egg cells by cutting the cells into thin sections and preserving them throughout different stages of development. An Atlas helped Wilson develop methods to present key stages of fertilization and development, which he later used in his textbook The Cell in Development and Inheritance, first published in 1896. Furthermore, An Atlas was the first publication to present accurate images of the fertilized egg cell during early stages of development.