![]() Viktor Hamburger and Howard Hamilton described 46 morphologically distinct stages of chick development beginning with a freshly laid egg and ending with a fully developed and hatched chick ( Hamburger and Hamilton, 1951). ![]() These early developmental studies eventually provided the foundation for the Hamburger-Hamilton stages of development ( Hamburger and Hamilton, 1951), which are still widely utilized. The Russian scientists, Karl Ernst von Baer and Heinz Christian Pander, used Beguelin's technique to describe the germ layers that form the embryo during development the ectoderm, mesoderm, and endoderm ( Romanoff, 1943).Īs embryology advanced, more complex histological studies were carried out using the chick egg, leading Mathias Marie Duval (1844-1907) to publish the first complete morphological atlas of chick morphology, Atlas d'embryologie, in 1889 ( Duval, 1889). By cutting a hole in the eggshell and covering it with a piece of shell from another egg to prevent dehydration, he was able to follow sequential developmental changes in the germinal disk ( Romanoff, 1943). The easy maintenance and relatively large size of the developing chick embryo allowed these significant observations using the simple tools of the 17 th century.Īround 1750, German scientist, Beguelin, introduced the technique of cultivating chick embryos in an open egg, which allowed scientists to follow a single chick embryo throughout its development. Inspired by Harvey's work, Marcello Malpighi used the chick to define and describe capillary vessels ( Malpighi, 1672). He also recognized the functional difference between arteries and veins ( Harvey, 1628). In these studies, William Harvey revealed that the heart began pumping even before blood development. Early chick studies identified components of the hematogenous circulatory system and recognized the heart as a central pump pushing blood directionally through a network of vessels ( Harvey, 1847 (published after death)). ![]() A rich background of information, coupled with new technologies and relative ease of maintenance suggest an expanding utility for the chick embryo in cardiac biology and cancer research.Ĭonserved characteristics are evident in the chick's use in understanding human development, including the genesis of the cardiovascular system. Moreover, progress in imaging and chick culture technologies is advancing real-time visualization of dynamic biological events, such as tissue morphogenesis, angiogenesis and cancer metastasis. With new molecular and genetic tools applied to the avian genome the chick embryo is accelerating the discovery of normal development and elusive disease processes. Despite the more recent arrival of several vertebrate and invertebrate animal models during the last century, the chick embryo remains a commonly used model for vertebrate biology and provides a tractable biological template. ![]() Fundamental discoveries, including the description of directional circulation propelled by the heart and the link between oncogenes and the formation of cancer, indicate its utility in cardiac biology and cancer. A long and productive history in biomedical research defines the chick as a model for human biology. ![]()
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