"In vitro Experiments on the Effects of Mouse Sarcomas 180 and 37 on the Spinal and Sympathetic Ganglia of the Chick Embryo" were experiments conducted by Rita Levi-Montalcini in conjunction with Viktor Hamburger and Hertha Meyer and published in Cancer Research in 1954. In this series of experiments, conducted at the University of Brazil, Levi-Montalcini demonstrated increased nerve growth by introducing specific tumors (sarcomas) to chick ganglia. Ganglia are clusters of nerve cells, from which nerve fibers emerge. This work led to the discovery of nerve growth factor (NGF) and later the Nobel Prize in Physiology or Medicine in 1986.

In "Selective Growth Stimulating Effects of Mouse Sarcoma on the Sensory and Sympathetic Nervous System of the Chick Embryo," Rita Levi-Montalcini and Viktor Hamburger explored the effects of two nerve growth stimulating tumors; mouse sarcomas 180 and 37. This experiment led to the discovery that nerve growth factor was a diffusible chemical and later to discoveries that the compound was a protein. Although this paper was an important step in the discovery of nerve growth factor, the term "nerve growth factor" was not used in this paper. It was instead referred to as a "growth promoting agent." The discovery of nerve growth factor earned Levi-Montalcini and Stanley Cohen, who also discovered epidermal growth factor, the 1986 Nobel Prize in Physiology or Medicine.

In 1980 Janet Rossant and William I. Frels published their paper, "Interspecific Chimeras in Mammals: Successful Production of Live Chimeras Between Mus musculus and Mus caroli," in Science. Their experiment involved the first successful creation of interspecific mammalian chimeras. Mammalian chimeras are valuable for studying early embryonic development. However, in earlier studies, clonal analysis was restricted by the lack of a cell marker, present at all times, that makes a distinction between the two parental cell types in situ. To battle this limitation, Rossant and Frels decided to make chimeras from embryos of two different species in order to have sufficient genetic differences so that, in any tissue type, the two cell types could be clearly identified. In their paper Rossant and Frels describe the successful creation of live chimeras between Mus musculus and Mus caroli. These two species of mice are more closely related than chimeras produced previously. The chimeras created in the experiment showed no sign of selection against one cell type or the other. Therefore, they are valuable for clonal analysis of development. Rossant and Frels were the first to successfully produce an interspecific mammalian chimera that experienced normal development.

The developmental stages of the chick embryo were examined by Viktor Hamburger and Howard L. Hamilton in "A Series of Normal Stages in the Development of the Chick Embryo," published in the Journal of Morphology in 1951. These stages were published to standardize the development of the chick based on varying laboratory conditions and genetic differences. The stages Hamburger and Hamilton assigned were determined by the visible features of the chick embryo. The first stage begins just prior to the primitive streak, with the formation of the embryonic shield, and the final stage, forty-six, ends at the hatching of the chick.

In "Versuche zur Analyse der Induktionsmittel in der Embryonalentwicklung," published in Naturwissenschaften in 1932, Hermann Bautzmann, Johannes Holtfreter, Otto Mangold, and Hans Spemann jointly reported on experiments each had conducted testing the activity of organizers killed by boiling, freezing, alcohol, and drying. Each of the authors had been independently conducting similar experiments, when Holtfreter made a breakthrough allowing him to produce many more successful transplantations. When he told Spemann the news, Spemann suggested that he tell Bautzmann, who had been working extensively on the question. Spemann then coordinated the joint paper to avoid a conflict among the researchers.

In this paper Viktor Hamburger and Rita Levi-Montalcini collaborated to examine the effects of limb transplantation and explantation on neural development. In 1947 Hamburger invited Levi-Montalcini to his lab at Washington University in St. Louis to examine this question. Independently, each had previously arrived at opposing conclusions based on the same data. Hamburger concluded that limb transplantations caused the ganglia to develop more connections and grow larger while Levi-Montalcini concluded that the ganglia first produce a large amount of neurons, then degenerate the unsuccessful neurons. She concluded that larger ganglia must be due to the increase in successful connections. This joint paper, published in the Journal of Experimental Zoology in 1949, corroborated the findings reported by Levi-Montalcini and established that nerve degeneration is an integral part of development.

Stanley Cohen published "Purification of a Nerve-Growth Promoting Protein from the Mouse Salivary Gland and its Neuro-Cytoxic Antiserum" in the Proceedings of the National Academies of Sciences in 1960. This paper outlined the successful purification and identification of nerve growth factor (NGF) as a protein, the developmental effects of depriving an embryo of NGF, and the discovery that NGF is also required for the maintenance of the nervous system.

In 1984 Sabine Meinecke-Tillmann and Burkhard Meinecke published their article "Experimental Chimeras - Removal of Reproductive Barrier Between Sheep and Goat" in Nature. Their study conquered the reproductive barrier between sheep and goats through embryo manipulation. Their article appeared in Nature on the same day that a similar experiment, conducted by Carole Fehilly, Steen Willadsen, and Elizabeth Tucker was published regarding reproductive barriers between sheep and goats. In previous experiments involving the transplantation of sheep embryos into recipient goats or vice versa, the embryos did not survive past the initial weeks of pregnancy. Hybridization experiments had also failed between the species. Although scientists were unsure of the reasons that hybrid eggs from donor sheep did not survive, they attributed the death of the hybrid eggs from donor goats to immunological responses. Meinecke-Tillmann and Meinecke created interspecific chimeric embryos in order to address the reproductive obstacles between the species. These embryos were transferred to sheep, and a sheep successfully brought a goat kid to term.

In "Behavioral Thermoregulation by Turtle Embryos," published in Proceedings of the National Academy of Sciences in April, 2011, Wei-Guo Du, Bo Zhao, Ye Chen, and Richard Shine report that turtle embryos can move towards warmer temperatures within the egg when presented with a small, 0.8 degrees Celsius gradient. This behavioral thermoregulation may benefit the embryo's fitness by accelerating the rate of development enough to decrease the incubation period by up to four and a half days. Embryos are generally thought to have little control over their surroundings. This study revealed that embryos may be able to control their developmental environment by modifying their behavior.

After becoming chief pathologist at the University of Wisconsin-Madison Wisconsin Regional Primate Center in 1995, James A. Thomson began his pioneering work in deriving embryonic stem cells from isolated embryos. That same year, Thomson published his first paper, "Isolation of a Primate Embryonic Stem Cell Line," in Proceedings of the National Academy of Sciences of the United States of America, detailing the first derivation of primate embryonic stem cells. In the following years, Thomson and his team of scientists - Joseph Itskovitz-Eldor, Sander S. Shapiro, Michelle A. Waknitz, Jennifer J. Swiergiel, Vivienne S. Marshall, and Jeffry M. Jones - advanced their work with embryonic stem cells, eventually isolating and culturing human embryonic stem cells. Their work with human embryos was reported in the 1998 Nature article "Embryonic Stem Cell Lines Derived from Human Blastocysts."