|
Morphogenetic Field
In the developmental biology of the early twentieth century, a morphogenetic field is a group of cells able to respond to discrete, localized biochemical signals leading to the development of specific morphological structures or organs. The spatial and temporal extents of the embryonic field are dynamic, and within the field is a collection of interacting cells out of which a particular organ is formed. As a group, the cells within a given morphogenetic field are constrained: thus, cells in a ''limb field'' will become a limb tissue, those in a ''cardiac field'' will become heart tissue. However, specific cellular programming of individual cells in a field is flexible: an individual cell in a cardiac field can be redirected via cell-to-cell signaling to replace specific damaged or missing cells. Imaginal discs in insect larvae are examples of morphogenetic fields. Historical development The concept of the morphogenetic field, fundamental in the early twentieth century to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morphogenetic
Morphogenesis (from the Greek ''morphê'' shape and ''genesis'' creation, literally "the generation of form") is the biological process that causes a cell, tissue or organism to develop its shape. It is one of three fundamental aspects of developmental biology along with the control of tissue growth and patterning of cellular differentiation. The process controls the organized spatial distribution of cells during the embryonic development of an organism. Morphogenesis can take place also in a mature organism, such as in the normal maintenance of tissue by stem cells or in regeneration of tissues after damage. Cancer is an example of highly abnormal and pathological tissue morphogenesis. Morphogenesis also describes the development of unicellular life forms that do not have an embryonic stage in their life cycle. Morphogenesis is essential for the evolution of new forms. Morphogenesis is a mechanical process involving forces that generate mechanical stress, strain, and mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ross Granville Harrison
Ross Granville Harrison (January 13, 1870 – September 30, 1959) was an American biologist and anatomist credited for his pioneering work on animal tissue culture. His work also contributed to the understanding of embryonic development. Harrison studied in many places around the world and made a career as a university professor. He was also a member of many learned societies and received several awards for his contributions to anatomy and biology. Education Harrison received his early schooling in Baltimore, where his family had moved from Germantown, Philadelphia. Announcing in his mid teens a resolve to study medicine, he entered Johns Hopkins University in 1886, receiving his BA degree in 1889 at the age of nineteen. In 1890, he worked as a laboratory assistant for the United States Fish Commission in Woods Hole, Massachusetts, studying the embryology of the oyster with his close friend E. G. Conklin and H. V. Wilson. In 1891, he participated in a marine zoology field trip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolutionary Developmental Biology
Evolutionary developmental biology (informally, evo-devo) is a field of biological research that compares the developmental processes of different organisms to infer how developmental processes evolved. The field grew from 19th-century beginnings, where embryology faced a mystery: zoologists did not know how embryonic development was controlled at the molecular level. Charles Darwin noted that having similar embryos implied common ancestry, but little progress was made until the 1970s. Then, recombinant DNA technology at last brought embryology together with molecular genetics. A key early discovery was of homeotic genes that regulate development in a wide range of eukaryotes. The field is composed of multiple core evolutionary concepts. One is deep homology, the finding that dissimilar organs such as the eyes of insects, vertebrates and cephalopod molluscs, long thought to have evolved separately, are controlled by similar genes such as ''pax-6'', from the evo-devo gene toolk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homeobox
A homeobox is a DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. For instance, mutations in a homeobox may change large-scale anatomical features of the full-grown organism. Homeoboxes are found within genes that are involved in the regulation of patterns of anatomical development (morphogenesis) in animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...s, fungus, fungi, plants, and numerous single cell eukaryotes. Homeobox genes encode homeodomain protein products that are transcription factors sharing a characteristic protein fold structure that binds DNA to regulate expression of target genes. Homeodomain proteins regulate gene expression and cell differentiation during early embryonic dev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ontogeny
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan. Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). While developmental (i.e., ontogenetic) processes can influence sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modern Synthesis (20th Century)
The modern synthesis was the early 20th-century synthesis of Charles Darwin's theory of evolution and Gregor Mendel's ideas on heredity into a joint mathematical framework. Julian Huxley coined the term in his 1942 book, ''Evolution: The Modern Synthesis''. The synthesis combined the ideas of natural selection, Mendelian inheritance, Mendelian genetics, and population genetics. It also related the broad-scale macroevolution seen by paleontology, palaeontologists to the small-scale microevolution of local population, populations. The synthesis was defined differently by its founders, with Ernst Mayr in 1959, G. Ledyard Stebbins in 1966, and Theodosius Dobzhansky in 1974 offering differing basic postulates, though they all include natural selection, working on heritable variation supplied by mutation. Other major figures in the synthesis included E. B. Ford, Bernhard Rensch, Ivan Schmalhausen, and George Gaylord Simpson. An early event in the modern synthesis was R. A. Fisher's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Hunt Morgan
Thomas Hunt Morgan (September 25, 1866 – December 4, 1945) was an American evolutionary biologist, geneticist, embryologist, and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries elucidating the role that the chromosome plays in heredity. Morgan received his Ph.D. from Johns Hopkins University in zoology in 1890 and researched embryology during his tenure at Bryn Mawr. Following the rediscovery of Mendelian inheritance in 1900, Morgan began to study the genetic characteristics of the fruit fly ''Drosophila melanogaster''. In his famous Fly Room at Columbia University's Schermerhorn Hall, Morgan demonstrated that genes are carried on chromosomes and are the mechanical basis of heredity. These discoveries formed the basis of the modern science of genetics. During his distinguished career, Morgan wrote 22 books and 370 scientific papers. As a result of his work, ''Drosophila'' became a major model organism in contemporary genetics. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Adolf Eduard Driesch
Hans Adolf Eduard Driesch (28 October 1867 – 17 April 1941) was a German biologist and philosopher from Bad Kreuznach. He is most noted for his early experimental work in embryology and for his neo-vitalist philosophy of entelechy. He has also been credited with performing the first artificial 'cloning' of an animal in the 1880s, although this claim is dependent on how one defines cloning. Early years Driesch was educated at the Gelehrtenschule des Johanneums. He began to study medicine in 1886 under August Weismann at the University of Freiburg. In 1887 he attended the University of Jena under Ernst Haeckel, Oscar Hertwig and Christian Ernst Stahl. In 1888 he studied physics and chemistry at the University of Munich. He received his doctorate in 1889. He travelled widely on field and study trips and lecture-tours, visiting Plymouth, India, Zurich and Leipzig where, in 1894, he published his ''Analytische Theorie der organischen Entwicklung'' or ''Analytic Theory of Organic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entelechy
In philosophy, potentiality and actuality are a pair of closely connected principles which Aristotle used to analyze motion, causality, ethics, and physiology in his ''Physics'', ''Metaphysics'', ''Nicomachean Ethics'', and ''De Anima''. The concept of potentiality, in this context, generally refers to any "possibility" that a thing can be said to have. Aristotle did not consider all possibilities the same, and emphasized the importance of those that become real of their own accord when conditions are right and nothing stops them. Actuality, in contrast to potentiality, is the motion, change or activity that represents an exercise or fulfillment of a possibility, when a possibility becomes real in the fullest sense. These concepts, in modified forms, remained very important into the Middle Ages, influencing the development of medieval theology in several ways. In modern times the dichotomy has gradually lost importance, as understandings of nature and deity have changed. Howev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paul Alfred Weiss
Paul Alfred Weiss (March 21, 1898 – September 8, 1989) was an Austrian biologist who specialised in morphogenesis, development, differentiation and neurobiology. A teacher, experimenter and theorist, he made a lasting contribution to science in his lengthy career, throughout which he sought to encourage specialists in different fields to meet and share insights. Paul Weiss was born in Vienna, the son of a Jewish couple, Carl S. Weiss, a businessman, and Rosalie Kohn Weiss. His background favoured music, poetry, and philosophy – Weiss himself was a violinist – but an uncle encouraged an interest in science. Weiss received his baccalaureate in 1916. After the end of the First World War, having served for three years as an officer in the artillery, he commenced studies in mechanical engineering at the Technische Hochschule in Vienna, (now Vienna University of Technology). He then shifted his focus to biology with a minor in physics. He absorbed the studies of Edmond B. Wilso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Spemann
Hans Spemann (; 27 June 1869 – 9 September 1941) was a German embryologist who was awarded a Nobel Prize in Physiology or Medicine in 1935 for his student Hilde Mangold's discovery of the effect now known as embryonic induction, an influence, exercised by various parts of the embryo, that directs the development of groups of cells into particular tissues and organs. Spemann added his name as an author to Hilde Mangold's dissertation (although she objected) and won a Nobel Prize for her work. Biography Hans Spemann was born in Stuttgart, the eldest son of publisher Wilhelm Spemann and his wife Lisinka, née Hoffman. After he left school in 1888 he spent a year in his father's business, then, in 1889–1890, he did military service in the Kassel Hussars followed by a short time as a bookseller in Hamburg. In 1891 he entered the University of Heidelberg where he studied medicine, taking his preliminary examination in 1893. There he met the biologist and psychologist Gustav Wolff w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander Gurvich
Alexander Gavrilovich Gurwitsch (also Gurvich, Gurvitch; russian: Алекса́ндр Гаври́лович Гу́рвич; 1874–1954) was a Russian and Soviet biologist and medical scientist who originated the morphogenetic field theory and discovered the biophoton. Early life Gurwitch was the son of a Jewish provincial lawyer; his family was artistic and intellectual, and he decided to study medicine only after failing to gain a place studying painting. After research in the laboratory of Karl Wilhelm von Kupffer, he began to specialise in embryology, publishing his first paper on the biochemistry of gastrulation in 1895. He graduated from Munich University in 1897, having studied under A. A. Boehm. Morphogenetic field theory After graduation, he worked in the histology laboratories of the universities of Strasbourg and Bern until 1907. At this time, he met his future wife and lifelong collaborator, the Russian-born medical trainee Lydia Felicine. His continuing interest, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
