On 9 August 2001, US President George W. Bush gave an eleven-minute speech from his ranch in Crawford, Texas, on the ethics and fate of federal funding for stem cell research. Bush also announced the creation of a special council to oversee stem cell research. In the speech President Bush acknowledged the importance of issues surrounding stem cell research to many Americans, presented different arguments in favor of and opposing embryonic stem cell research, and explained his decision to limit but not completely eliminate potential federal funding for embryonic stem cell (ESC) research. The speech was important to embryology as a field because it determined the US government's policy on funding human ESC research for the eight years of George W. Bush's administration.

Of Sir D'Arcy Thompson's nearly 300 publications, the theoretical treatise On Growth and Form, first published in 1917, remains the principal work for which he is remembered. This substantial book is still in print today, and merited an editorial review and introductory essays by two important twentieth century biologists, John Tyler Bonner and Stephen Jay Gould. Growth and Form was immediately well-received for both its literary style and its scientific significance, as discussed by the biologist Sir Peter Medawar. Despite being almost continuously in print since its first publication, the exact influence of Growth and Form on the biological sciences, although widely acknowledged, is yet difficult to characterize. In this work Thompson aimed to unite physics and biology through an analysis of the physical limitations to the growth and structure of organisms. For developmental biologists in particular, Thompson's theory on the transformation of biological forms, presented in the final chapter of Growth and Form, was thought provoking.

Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Organs is the thirteenth chapter of Charles Darwin's book The Origin of Species, first published in England in 1859. The book details part of Darwin's argument for the common ancestry of life and natural selection as the cause of speciation. In this chapter, Darwin summarizes the evidence for evolution by connecting observations of development in organisms to the processes of natural selection. Darwin shows how the theory of special creation, which claims that God directly created all organisms in their current form, is inferior to the theory of natural selection for its ability to explain the diversity of life. In this chapter, Darwin also discusses classification and homology as they relate to natural selection.

In 2011, fetal researcher Vivette Glover published “Annual Research Review: Prenatal Stress and the Origins of Psychopathology: An Evolutionary Perspective,” hereafter, “Prenatal Stress and the Origins of Psychopathology,” in the Journal of Child Psychology and Psychiatry. In that article, Glover explained how an evolutionary perspective may be useful in understanding the effects of fetal programming. Fetal programming is a hypothesis that attempts to explain how factors during pregnancy can affect fetuses after birth. Researchers associate exposure to prenatal stress, or stress experienced before birth, with an increased likelihood of some mental disorders. Glover states that such outcomes may be traced back to a fetus’s response to stress during pregnancy, and that those outcomes may have been beneficial in the past. By taking an evolutionary approach toward understanding mental disorders, Glover provided insights for studying the lasting effects of maternal stress during pregnancy on children’s mental health.

Induced pluripotent stem cells (iPSCs) are studied carefully by scientists not just because they are a potential source of stem cells that circumvents ethical controversy involved with experimentation on human embryos, but also because of their unique potential to advance the field of regenerative medicine. First generated in a lab by Kazutoshi Takahashi and Shinya Yamanaka in 2006, iPSCs have the ability to differentiate into cells of all types. If scientists discover how to induce differentiated cells to return to a pluripotent state using a method that leaves the iPSCs safe for transplantation, then patients could receive stem cell transplants with cells containing their own DNA. This would presumably remove the danger of transplant rejection that comes with foreign cell transplantation.

In 2009, A. John Henderson and colleagues published “Mothers’ Anxiety During Pregnancy Is Associated with Asthma in Their Children,” hereafter, “Mothers’ Anxiety,” in The Journal of Allergy and Clinical Immunology. Previous studies had shown that maternal stress during pregnancy affects children’s health during childhood. The researchers explored the association of asthma in children with maternal anxiety during pregnancy. The cause of asthma is often unknown. Thus, the researchers tested the possibility that maternal anxiety may increase disease risk in the children, particularly the development of asthma. The authors reported a positive association between maternal anxiety during pregnancy and asthma in offspring, indicating the possibility of a causal relationship. The authors’ findings demonstrated the health effects of maternal stress during pregnancy on children’s physiological and immune development.

Induced Pluripotent Stem Cells (iPSCs) are cells derived from non-pluripotent cells, such as adult somatic cells, that are genetically manipulated so as to return to an undifferentiated, pluripotent state. Research on iPSCs, initiated by Shinya Yamanaka in 2006 and extended by James Thompson in 2007, has so far revealed the same properties as embryonic stem cells (ESCs), making their discovery potentially very beneficial for scientists and ethicists alike. By avoiding the destruction of embryos and the complicated technique and resource requirements of ESCs, iPSCs may prove more practical and attractive than ESC research in the study of pluripotent stem cells.

German embryologist Viktor Hamburger came to the US in 1932 with a fellowship provided by the Rockefeller Foundation. Hamburger started his research in Frank Rattray Lillie's laboratory at the University of Chicago. His two-year work on the development of the central nervous system (CNS) in chick embryos was crystallized in his 1934 paper, "The Effects of Wing Bud Extirpation on the Development of the Central Nervous System in Chick Embryos," published in The Journal of Experimental Zoology. Hamburger was able to use the microsurgical techniques that he had learned from Hans Spemann to show how wing buds influence the development of the CNS in chick embryos. This paper is one of several among Hamburger's important studies on chick embryos and represents the empirical and theoretical cornerstone for his further research on central-peripheral relations in the development of the nervous system.

In the July 2007 issue of Nature, Keisuke Okita, Tomoko Ichisaka, and Shinya Yamanaka added to the new work on induced pluripotent stem cells (iPSCs) with their "Generation of Germline-Competent Induced Pluripotent Stem Cells" (henceforth abbreviated "Generation"). The authors begin the paper by noting their desire to find a method for inducing somatic cells of patients to return to a pluripotent state, a state from which the cell can differentiate into any type of tissue but cannot form an entire organism. If this is made possible, the authors claim, the ethical controversy surrounding the use of embryonic stem cells (ES cells) and the dangers of patient rejection of donated ES cells could be bypassed completely.

"Apoptosis: A Basic Biological Phenomenon with Wide-Ranging Implications in Tissue Kinetics" (hereafter abbreviated as "Apoptosis") was published in the British Journal of Cancer in 1972 and co-authored by three pathologists who collaborated at the University of Aberdeen, Scotland. In this paper the authors propose the term apoptosis for regulated cell death that proceeds through active, controlled morphological changes. This is in contrast to necrosis, a passive mode of cell death that results from uncontrolled cellular reactions to injury or stress. The journal article also suggests that apoptosis plays crucial roles in various pathological and physiological conditions including the shaping of digits and the shrinking of vestigial organs in developing embryos.