Embryo Project Encyclopedia

The case of Smith v. Cote (1986) answered two important questions concerning law and childbirth: does the State of New Hampshire recognize a cause of action for what is defined as wrongful birth, and does the State recognize a cause of action for what is classified as wrongful life? In the case of Smith v. Cote, damages were permitted for wrongful birth, but not for the action of wrongful life.

Stephen Jay Gould studied snail fossils and worked at Harvard University in Cambridge, Massachusetts during the latter half of the twentieth century. He contributed to philosophical, historical, and scientific ideas in paleontology, evolutionary theory, and developmental biology. Gould, with Niles Eldredge, proposed the theory of punctuated equilibrium, a view of evolution by which species undergo long periods of stasis followed by rapid changes over relatively short periods instead of continually accumulating slow changes over millions of years. In his 1977 book, Ontogeny and Phylogeny, Gould reconstructed a history of developmental biology and stressed the importance of development to evolutionary biology. In a 1979 paper coauthored with Richard Lewontin, Gould and Lewonitn criticized many evolutionary bioligists for relying solely on adaptive evolution as an explanation for morphological change, and for failing to consider other explanations, such as developmental constraints.

The Case against Perfection: Ethics in the Age of Genetic Engineering, hereafter referred to as The Case against Perfection, written by Michael J. Sandel, builds on a short essay featured in The Atlantic Monthly magazine in 2004. Three years later, Sandel transformed his article into a book, keeping the same title but expanding upon his personal critique of genetic engineering. The purpose of Sandel's book is to articulate the sources of what he considers to be widespread public unease related to genetic engineering that changes the course of natural development.

This diagram shows how NCCs migrate differently in rats, birds and amphibians. The arrows represent both chronology of NCCs migration and the differential paths that NCCs follow in different classes of animals. The solid black portion of each illustration represents the neural crest, and the large black dots in (c) and in (f) represent the neural crest cells. The speckled sections that at first form a basin in (a) and then close to form a tube in (f) represent the neural ectoderm. The solid white portions represent the epidermal ectoderm. During the neurula stage of all vertebrate embryos (a), the neural crest is located in two places on the neural plate. As the neural tube forms (b), a process called neurulation, the neural crest moves with the folding plate as it forms the junction between the neural and epidermal ectoderm. NCCs migrate differently in different classes of vertebrates (c-f). For instance, in rats (c), the NCCs migrate away from the neural crest before neurulation completes and while the neural fold is still open. In birds (d and f), neural crest cells do not migrate until the neural fold closes. In amphibians (e and f), the neural crest cells migrate after neurulation completes, and only after the cells have accumulated above the neural tube. Subsequently, NCCs will all migrate down their specialized pathways and diversify into the several sub-types of NCCs.

Rh incompatibility occurs when a pregnant woman whose blood type is Rh-negative is exposed to Rh-positive blood from her fetus, leading to the mother s development of Rh antibodies. These antibodies have the potential to cross the placenta and attach to fetal red blood cells, resulting in hemolysis, or destruction of the fetus 's red blood cells. This causes the fetus to become anemic, which can lead to hemolytic disease of the newborn. In severe cases, an intrauterine blood transfusion for the fetus may be required to correct the anemia.

Ontogeny and Phylogeny is a book published in 1977, in which the author Stephen J. Gould, who worked in the US, tells a history of the theory of recapitulation. A theory of recapitulation aims to explain the relationship between the embryonic development of an organism (ontogeny) and the evolution of that organism's species (phylogeny). Although there are several variations of recapitulationist theories, most claim that during embryonic development an organism repeats the adult stages of organisms from those species in it's evolutionary history. Gould suggests that, although fewer biologists invoked recapitulation theories in the twentieth century compared to those in the nineteenth and eighteenth centuries, some aspects of the theory of recapitulation remained important for understanding evolution. Gould notes that the concepts of acceleration and retardation during development entail that changes in developmental timing (heterochrony) can result in a trait appearing either earlier or later than normal in developmental processes. Gould argues that these changes in the timing of embryonic development provide the raw materials or novelties upon which natural selection acts.

The Spandrels of San Marco and the Panglossian Paradigm:
A Critique of the Adaptationist Programme, hereafter called
The Spandrels, is an article written by Stephen J. Gould and
Richard C. Lewontin published in the Proceedings of the Royal
Society of London in 1979. The paper emphasizes issues with
what the two authors call adaptationism or the adaptationist
programme as a framework to explain how species and traits evolved. The paper
is one in a series of works in which Gould emphasized the
role of development in evolutionary theories. The article suggests
that constraints on how organisms can develop and constraints on how species can evolve from others play a
central role in explaining the how species and traits evolve. The
authors note that organisms from different species develop as
embryos through stages similar across species, genera, and higher
classes. Gould and Lewontin hypothesize that those stages
constrained the possible pathways of evolution and has therefore
guided the history of life. Throughout the paper, the authors rely on analogy of some parts of organisms to architectural structures called spandrels, marked in this image as 'a'."

The biogenetic law is a theory of development and evolution proposed by Ernst Haeckel in Germany in the 1860s. It is one of several recapitulation theories, which posit that the stages of development for an animal embryo are the same as other animals' adult stages or forms. Commonly stated as ontogeny recapitulates phylogeny, the biogenetic law theorizes that the stages an animal embryo undergoes during development are a chronological replay of that species' past evolutionary forms. The biogenetic law states that each embryo's developmental stage represents an adult form of an evolutionary ancestor. According to the law, by studying the stages of embryological development, one is, in effect, studying the history and diversification of life on Earth. The biogenetic law implied that researchers could study evolutionary relationships between taxa by comparing the developmental stages of embryos for organisms from those taxa. Furthermore, the evidence from embryology supported the theory that all of species on Earth share a common ancestor.

Neurocristopathies are a class of pathologies in vertebrates,
including humans, that result from abnormal expression, migration,
differentiation, or death of neural crest cells (NCCs) during embryonic development. NCCs are cells
derived from the embryonic cellular structure called the neural crest.
Abnormal NCCs can cause a neurocristopathy by chemically affecting the
development of the non-NCC tissues around them. They can also affect the
development of NCC tissues, causing defective migration or
proliferation of the NCCs. There are many neurocristopathies
that affect many different types of systems. Some neurocristopathies
result in albinism (piebaldism) and cleft palate in humans. Various
pigment, skin, thyroid, and hearing disorders, craniofacial and heart
abnormalities, malfunctions of the digestive tract, and tumors can be
classified as neurocristopathies. This classification ties a variety of
disorders to one embryonic origin.

Early in the process of development, vertebrate embryos develop a fold on the neural plate where the neural and epidermal ectoderms meet, called the neural crest. The neural crest produces neural crest cells (NCCs), which become multiple different cell types and contribute to tissues and organs as an embryo develops. A few of the organs and tissues include peripheral and enteric (gastrointestinal) neurons and glia, pigment cells, cartilage and bone of the cranium and face, and smooth muscle. The diversity of NCCs that the neural crest produces has led researchers to propose the neural crest as a fourth germ layer, or one of the primary cellular structures in early embryos from which all adult tissues and organs arise. Furthermore, evolutionary biologists study the neural crest because it is a novel shared evolutionary character (synapomorphy) of all vertebrates.