Embryo Project Encyclopedia Articles

In 2001, the Supreme Court of New Jersey decided a dispute between a divorced couple over cryopreserved preembryos created through in vitro fertilization (IVF) during the coupleÕs marriage. The former wife (J.B.) wanted the preembryos destroyed, while her former husband (M.B.) wanted them to be used for future implantation attempts, such as by an infertile couple. In J.B. v. M.B. (2001), the court declined to force J.B. to become a parent against her will, concluding that doing so would violate state public policy. Instead, the Supreme Court of New Jersey decided that agreements directing the allocation of cryopreserved preembryos will be enforced, unless one party changes his or her mind prior to the preembryosÕ use or destruction. Should a party revoke an earlier decision about the preembryos, New Jersey courts should weigh the partiesÕ interests with special weight given to an individualÕs right to not procreate.

Wilhelm Johannsen in Denmark first proposed the distinction between genotype and phenotype in the study of heredity in 1909. This distinction is between the hereditary dispositions of organisms (their genotypes) and the ways in which those dispositions manifest themselves in the physical characteristics of those organisms (their phenotypes). This distinction was an outgrowth of Johannsen's experiments concerning heritable variation in plants, and it influenced his pure line theory of heredity. While the meaning and significance of the genotype-phenotype distinction has been a topic of debate-among Johannsen's contemporaries, later biological theorists, and historians of science-many consider the distinction one of the conceptual pillars of twentieth century genetics. Moreover some have used it to characterize the relationships between studies of development, genetics, and evolution.

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.

Plastination is a technique for preserving tissues, organs, and whole bodies for medical purposes and public display. Gunther von Hagens invented a form of the method in 1977 at Heidelberg University in Heidelberg, Germany after observing medical students struggle working with cadavers that quickly decomposed. Von Hagens' body models, referred to as plastinates, have since become widely used educational tools not only for those studying anatomy and medicine, but also for the general public. The technique has contributed to the fields of medicine, anatomy, and embryology by accurately preserving tissues for use in research and education.

James Marion Sims developed a surgical cure for ruptures of the wall separating the bladder from the vagina during labor, ruptures called vesico-vaginal fistulas, and he developed techniques and tools used to improve reproductive examinations and health care for women in the US during the nineteenth century. Sims's lateral examination position allowed doctors to better see the vaginal cavity, and his speculum, a spoon-like object used for increased view into the vagina, helped to make gynecological examinations more thorough. Sims helped ease the physical and social strains of post-birth women who suffered from vesico-vaginal fistulas, and he established the first hospital in New York City, New York, dedicated solely to treating women and improving women's health care.

Calvin Blackman Bridges studied chromosomes and heredity in the US throughout the early twentieth century. Bridges performed research with Thomas Hunt Morgan at Columbia University in New York City, New York, and at the California Institute of Technology in Pasadena, California. Bridges and Morgan studied heredity in Drosophila, the common fruit fly. Throughout the early twentieth century, researchers were gathering evidence that genes, or what Gregor Mendel had called the factors that control heredity, are located on chromosomes. At Columbia, Morgan disputed the theory, but in 1916, Calvin Bridges published evidence that, according to Morgan, did much to convince skeptics of that theory. Bridges also established that specific chromosomes function in determining sex in Drosophila.

Alfred Henry Sturtevant studied heredity in fruit flies in the US throughout the twentieth century. From 1910 to 1928, Sturtevant worked in Thomas Hunt Morgan’s research lab in New York City, New York. Sturtevant, Morgan, and other researchers established that chromosomes play a role in the inheritance of traits. In 1913, as an undergraduate, Sturtevant created one of the earliest genetic maps of a fruit fly chromosome, which showed the relative positions of genes along the chromosome. At the California Institute of Technology in Pasadena, California, he later created one of the first fate maps, which tracks embryonic cells throughout their development into an adult organism. Sturtevant’s contributions helped scientists explain genetic and cellular processes that affect early organismal development.

From 1913 to 1916, Calvin Bridges performed experiments that indicated genes are found on chromosomes. His experiments were a part of his doctoral thesis advised by Thomas Hunt Morgan in New York, New York. In his experiments, Bridges studied Drosophila, the common fruit fly, and by doing so showed that a process called nondisjunction caused chromosomes, under some circumstances, to fail to separate when forming sperm and egg cells. Nondisjunction, as described by Bridges, caused sperm or egg cells to contain abnormal amounts of chromosomes. In some cases, that caused the offspring produced by the sperm or eggs to display traits that they would typically not have. His research on nondisjunction provided evidence that chromosomes carry genetic traits, including those that determine the sex of an organism.

In November 1921, US Congress passed the National Maternity and Infancy Protection Act, also called the Sheppard-Towner Act. The Act provided federal funds to states to establish programs to educate people about prenatal health and infant welfare. Advocates argued that it would curb the high infant mortality rate in the US. Many states accepted funding through the Sheppard-Towner Act, leading to the establishment of nearly 3,000 prenatal care clinics, 180,000 infant care seminars, over three million home visits by traveling nurses, and a national distribution of educational literature between 1921 and 1928. The Act provided funding for five years, but was repealed in 1929 after Congress did not renew it. Historians note that infant mortality did decrease during the years the Act was in effect. The Act also influenced provisions aimed at infant and maternity welfare in later legislation, such as the Social Security Act of 1935.

In 1910, Thomas Hunt Morgan performed an experiment at Columbia University, in New York City, New York, that helped identify the role chromosomes play in heredity. That year, Morgan was breeding Drosophila, or fruit flies. After observing thousands of fruit fly offspring with red eyes, he obtained one that had white eyes. Morgan began breeding the white-eyed mutant fly and found that in one generation of flies, the trait was only present in males. Through more breeding analysis, Morgan found that the genetic factor controlling eye color in the flies was on the same chromosome that determined sex. That result indicated that eye color and sex were both tied to chromosomes and helped Morgan and colleagues establish that chromosomes carry the genes that allow offspring to inherit traits from their parents.