Embryo Project Encyclopedia Articles

Acid dissolution is a technique of removing a fossil from the surrounding rock matrix in which it is encased by dissolving that matrix with acid. Fossilized bone, though strong enough to be preserved for thousands or millions of years, is often more delicate than rock. Once a fossil is discovered, scientists must remove the fossil from its surroundings without damaging the fossil itself. Scientists have used chemicals to expose vertebrate fossils since the 1930s, and in the late 1990s Terry Manning, an amateur scientist and technician working in England, adapted the technology to dinosaur eggs. Manning used acid dissolution on dinosaur eggs to expose the embryos beneath the rock and fossil shell. Manning's acid dissolution enabled scientists to better study the remains of dinosaur embryos otherwise hidden beneath layers of eggshell and rock, revealing previously unrecorded aspects of dinosaur growth and development.

Boris Ephrussi and George Wells Beadle developed a transplantation technique on flies, Drosophila melanogaster, which they described in their 1936 article A Technique of Transplantation for Drosophila. The technique of injecting a tissue from one fly larva into another fly larva, using a micropipette, to grow that tissue in the second larvae, was a means for investigating development of Drosophila. Through this technique, Beadle and Ephrussi studied the role of genes in embryological processes. Beadle and Ephrussi were the first to apply the transplantation method, which had previously been used in the study of larger insects, to the smaller sized Drosophila. Beadle and Ephrussi used this method of transplantation to determine if parts of the optic disc, the section of a larvae that later become the eye buds in the adult, could be extracted from one larva and transplanted into another. They later built upon this research to relate the production of molecules in cells to gene function.

Regeneration is a fascinating phenomenon. The fact that many organisms have the capacity to regenerate lost parts and even remake complete copies of themselves is difficult to fathom; so difficult, in fact, that for a very long time people were reluctant to believe regeneration actually took place. It seemed unbelievable that some organisms could re-grow lost limbs, organs, and other body parts. If only we could do the same! Unfortunately, our regenerative capacities are limited to hair, nails, and skin, while the liver and a few other tissues display more restricted regenerative abilities. What if we could grow back lost limbs, or damaged organs? This question has inspired many stories, dating back to Greek mythology, wherein Prometheus was doomed to regenerate his liver after it had been devoured by birds. Regeneration has permeated many imaginations; it has appeared in many literary and religious texts, and has also provoked much interest from the scientific community.

Although educated as a scientist who studied with both August Weismann and Ernst Heinrich Haeckel, Hans Adolf Eduard Driesch was first employed as a professor of philosophy and became a strong proponent of vitalism. Driesch was born on 28 October 1867, the only child of Josefine Raudenkolb and Paul Driesch. He grew up in a wealthy merchant family in Hamburg, Germany, where he was educated at the humanistic Gymnasium Gelehrtenschule des Johanneums that had been founded by a friend of Martin Luther. In 1886 he spent two summers studying with Weismann at the University of Freiburg and then entered the University of Jena, where he received his doctorate in 1889 with a study of hydroid colonies. By 1890 Driesch had lost interest in Haeckel's popular phylogenetic approach to zoology and instead focused on experimental embryology.

This video is composed of a sequence of films created by John Tyler Bonner in the 1940s to show the life cycle of the cellular slime mold Dictyostelium discoideum. As only the second person to study slime molds, Bonner frequently encountered audiences who had never heard of, let alone seen, the unusual organism. He therefore decided to create a film to present at seminars in order to introduce his object of study; the time-lapsed film captivated audiences, indeed Bonner has described that the film "always stole the show." Bonner began working in the biology department at Princeton University in 1947, and although Princeton appears in the opening title, Bonner actually made the film for his senior thesis as an undergraduate at Harvard University with some early assistance from Frank Smith, a photographer. Although unsure of name of the device that was used for filming, he has described it as "the most amazing antique contraption that belonged to my professor, Wm. H. Weston. It consisted of a gigantic and VERY heavy set of brass gears that had numerous possible speeds that turned a crank on the side of an old 16 mm box camera that pointed into the ocular of a microscope. The electric motor that propelled it made such vibrations that the whole apparatus had to be on a separate table and not touching the microscope."

The gradient theory is recognized as Charles Manning Child's most significant scientific contribution. Gradients brought together Child's interest in development and his fascination with the origins of individuality and organization. The gradient theory grew from his studies of regeneration, which were largely based on work he conducted with marine invertebrates, such as the ascidian flat worm, planaria and the hydroid, tubularia. Child observed that regeneration occurred in a graded process along the axis of the organism, with the characteristics of each physiological process seemingly determined by its location along the axis. To explain these observations, Child posited the existence of physiological factors working to guide the regenerative process. He was convinced that these differences along the gradients could be explained quantitatively.

When scientists discovered a 3.3
million-year-old skeleton of a child of the human lineage (hominin) in
2000, in the village of Hadar, Ethiopia, they were able to study growth
and development of Australopithecus
afarensis, an extinct hominin species. The team of researchers,
led by Zeresenay Alemseged of the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, named the fossil DIK 1-1 and nicknamed
it Dikika baby after the Dikika research site. The Dikika fossil
preserves much of the skull, including the jaw and teeth, which enabled
scientists to study the teeth microstructures and to reconstruct the
pace at which individuals of the hominin A. afarensis
developed.

The Edinburgh Mouse Atlas, also called the e-Mouse Atlas Project (EMAP), is an online resource comprised of the e-Mouse Atlas (EMA), a detailed digital model of mouse development, and the e-Mouse Atlas of Gene Expression (EMAGE), a database that identifies sites of gene expression in mouse embryos. Duncan Davidson and Richard Baldock founded the project in 1992, and the Medical Research Council (MRC) in Edinburgh, United Kingdom, funds the project. Davidson and Baldock announced the project in an article titled A Real Mouse for Your Computer, citing the need to manage and analyze the volume of data that overwhelmed developmental biologists. Though EMAP resources were distributed via CD-ROM in the early years, the project moved increasingly online by the early 2000s, and into the early decades of the twenty-first century, was in active development. EMAP can be utilized as a developmental biology teaching resource and as a research tool that enables scientists to explore annotated 3D virtual mouse embryos. EMAP's goal is to illuminate the molecular basis of tissue differentiation.

James William Kitching collected and studied fossils of dinosaurs and early humans in the twentieth century. He worked at the Bernard Price Institute for Paleontological Research in South Africa. During the fifty-three years he worked at the institute, Kitching spent eighteen of those in the field uncovering fossils. Kitching recovered fossils of early human ancestors, later called Australopithecines, as well as fossils of dinosaurs and ancient mammals. When he died in 2003, the Bernard Price Institute housed one of the largest fossil collections in the southern hemisphere. Kitching and his team had collected most of those fossils. Additionally, he helped discover Massospondylus embryos, the first dinosaur embryos ever recovered, which enabled scientists to examine dinosaurs before birth.