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Preformation
In the history of biology, preformationism (or preformism) is a formerly popular theory that organisms develop from miniature versions of themselves. Instead of assembly from parts, preformationists believed that the form of living things exist, in real terms, prior to their development.Maienschein, Jane,Epigenesis and Preformationism, The Stanford Encyclopedia of Philosophy (Fall 2008 Edition), Edward N. Zalta (ed.). It suggests that all organisms were created at the same time, and that succeeding generations grow from homunculi, or animalcules, that have existed since the beginning of creation, which is typically defined by religious beliefs. EpigenesisAccording to the Oxford English Dictionary: It is also worth quoting this adumbration of the definition given there (viz., "The formation of an organic germ as a new product"): (or neoformism), then, in this context, is the denial of preformationism: the idea that, in some sense, the form of living things comes into existence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homunculus
A homunculus ( , , ; "little person") is a representation of a small human being, originally depicted as small statues made out of clay. Popularized in sixteenth-century alchemy and nineteenth-century fiction, it has historically referred to the creation of a miniature, fully formed human. The concept has roots in preformationism as well as earlier folklore and alchemic traditions. The term lends its name to the cortical homunculus, an image of a person with the size of the body parts distorted to represent how much area of the cerebral cortex of the brain is devoted to it. History Alchemy The homunculus first appears by name in alchemical writings attributed to Paracelsus (1493–1541). ''De natura rerum'' (1537) outlines his method for creating homunculi: Comparisons have been made with several similar concepts in the writings of earlier alchemists. Although the actual word "homunculus" was never used, Carl Jung believed that the concept first appeared in the ''Visions of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preformation
In the history of biology, preformationism (or preformism) is a formerly popular theory that organisms develop from miniature versions of themselves. Instead of assembly from parts, preformationists believed that the form of living things exist, in real terms, prior to their development.Maienschein, Jane,Epigenesis and Preformationism, The Stanford Encyclopedia of Philosophy (Fall 2008 Edition), Edward N. Zalta (ed.). It suggests that all organisms were created at the same time, and that succeeding generations grow from homunculi, or animalcules, that have existed since the beginning of creation, which is typically defined by religious beliefs. EpigenesisAccording to the Oxford English Dictionary: It is also worth quoting this adumbration of the definition given there (viz., "The formation of an organic germ as a new product"): (or neoformism), then, in this context, is the denial of preformationism: the idea that, in some sense, the form of living things comes into existence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryology
Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses. Additionally, embryology encompasses the study of congenital disorders that occur before birth, known as teratology. Early embryology was proposed by Marcello Malpighi, and known as preformationism, the theory that organisms develop from pre-existing miniature versions of themselves. Aristotle proposed the theory that is now accepted, epigenesis. Epigenesis is the idea that organisms develop from seed or egg in a sequence of steps. Modern embryology, developed from the work of Karl Ernst von Baer, though accurate observations had been made in Italy by anatomists such as Aldrovandi and Leonardo da Vinci in the Renaissance. Comparative embryology Preformationism and epigenesis As recently as the 18th century, the prevailin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epigenesis (biology)
In biology, epigenesis (or, in contrast to preformationism, neoformationism) is the process by which plants, animals and fungi develop from a seed, spore or egg through a sequence of steps in which cells differentiate and organs form. Aristotle first published the theory of epigenesis in his book ''On the Generation of Animals.'' Although epigenesis appears to be an obvious fact in today's genetic age, historically, creationist theories of life's origins hindered its acceptance. However, during the late 18th century an extended and controversial debate among biologists finally led epigenesis to eclipse the long-established preformationist view.Conference, Abstracts of papers presented. The embryologist Caspar Friedrich Wolff refuted preformationism in 1759 in favor of epigenesis, but this did not put an end to preformationism. See also * Epigenetics In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weismann Barrier
The Weismann barrier, proposed by August Weismann, is the strict distinction between the "immortal" germ cell lineages producing gametes and "disposable" somatic cells in animals (but not plants), in contrast to Charles Darwin's proposed pangenesis mechanism for inheritance. In more precise terminology, hereditary information moves only from germline cells to somatic cells (that is, somatic mutations are not inherited). This does not refer to the central dogma of molecular biology, which states that no sequential information can travel from protein to DNA or RNA, but both hypotheses relate to a gene-centric view of life. Weismann set out the concept in his 1892 book ''Das Keimplasma: eine Theorie der Vererbung'' (The Germ Plasm: a theory of inheritance). The Weismann barrier was of great importance in its day and among other influences it effectively banished certain Lamarckian concepts: in particular, it would make Lamarckian inheritance from changes to the body (the soma) diffi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epigenetics
In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "on top of" or "in addition to" the traditional genetic basis for inheritance. Epigenetics most often involves changes that affect the regulation of gene expression, but the term can also be used to describe any heritable phenotypic change. Such effects on cellular and physiological phenotypic traits may result from external or environmental factors, or be part of normal development. The term also refers to the mechanism of changes: functionally relevant alterations to the genome that do not involve mutation of the nucleotide sequence. Examples of mechanisms that produce such changes are DNA methylation and histone modification, each of which alters how genes are expressed without altering the underlying DNA sequence. Gene expression c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aristotle
Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of philosophy within the Lyceum and the wider Aristotelian tradition. His writings cover many subjects including physics, biology, zoology, metaphysics, logic, ethics, aesthetics, poetry, theatre, music, rhetoric, psychology, linguistics, economics, politics, meteorology, geology, and government. Aristotle provided a complex synthesis of the various philosophies existing prior to him. It was above all from his teachings that the West inherited its intellectual lexicon, as well as problems and methods of inquiry. As a result, his philosophy has exerted a unique influence on almost every form of knowledge in the West and it continues to be a subject of contemporary philosophical discussion. Little is known about his life. Aristotle was born in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galen
Aelius Galenus or Claudius Galenus ( el, Κλαύδιος Γαληνός; September 129 – c. AD 216), often Anglicized as Galen () or Galen of Pergamon, was a Greek physician, surgeon and philosopher in the Roman Empire. Considered to be one of the most accomplished of all medical researchers of antiquity, Galen influenced the development of various scientific disciplines, including anatomy, physiology, pathology, pharmacology, and neurology, as well as philosophy and logic. The son of Aelius Nicon, a wealthy Greek architect with scholarly interests, Galen received a comprehensive education that prepared him for a successful career as a physician and philosopher. Born in the ancient city of Pergamon (present-day Bergama, Turkey), Galen traveled extensively, exposing himself to a wide variety of medical theories and discoveries before settling in Rome, where he served prominent members of Roman society and eventually was given the position of personal physician to several emp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Realdo Colombo
Matteo Realdo Colombo (c. 1515 – 1559) was an Italian professor of anatomy and a surgeon at the University of Padua between 1544 and 1559. Early life and education Matteo Realdo Colombo or Realdus Columbus, was born in Cremona, Lombardy, the son of an apothecary named Antonio Colombo. Although little is known about his early life, it is known he took his undergraduate education in Milan, where he studied philosophy, and he appears to have pursued his father's profession for a short while afterwards. He left the apothecary's life and apprenticed to the surgeon Giovanni Antonio Lonigo, under whom he studied for 7 years. In 1538 he enrolled in the University of Padua where he was noted to be an exceptional student of anatomy. While still a student, he was awarded a Chair of Sophistics at the university. In 1542 he returned briefly to Venice to assist his mentor, Lonigo. Academic career Realdo Colombo studied philosophy in Milan, and then he trained to be a surgeon for several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Harvey
William Harvey (1 April 1578 – 3 June 1657) was an English physician who made influential contributions in anatomy and physiology. He was the first known physician to describe completely, and in detail, the systemic circulation and properties of blood being pumped to the brain and the rest of the body by the heart, though earlier writers, such as Realdo Colombo, Michael Servetus, and Jacques Dubois, had provided precursors of the theory. Family William's father, Thomas Harvey, was a jurat of Folkestone where he served as mayor in 1600. Records and personal descriptions delineate him as an overall calm, diligent, and intelligent man whose "sons... revered, consulted and implicitly trusted in him... (they) made their father the treasurer of their wealth when they acquired great estates...(He) kept, employed, and improved their gainings to their great advantage." Thomas Harvey's portrait can still be seen in the central panel of a wall of the dining room at Rolls Park, Chig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Girolamo Fabrici
Girolamo Fabrici d'Acquapendente, also known as Girolamo Fabrizio or Hieronymus Fabricius (20 May 1533 – 21 May 1619), was a pioneering anatomist and surgeon known in medical science as "The Father of Embryology." Life and accomplishments Born in Acquapendente, Latium, Fabricius studied at the University of Padua, receiving a Doctor of Medicine degree in 1559 under the guidance of Gabriele Falloppio. He was a private teacher of anatomy in Padua, 1562–1565, and in 1565, became professor of surgery and anatomy at the university, succeeding Falloppio. In 1594 he revolutionized the teaching of anatomy when he designed the first permanent theater for public anatomical dissections. Julius Casserius (1552–1616) of Piacenza was among Fabricius' students. William Harvey (1578–1657) and Adriaan van den Spiegel (1578–1625) also studied under Fabricius, beginning around 1598. Julius Casserius would later succeed Fabricius as Professor of Anatomy at the University of Padua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Developmental Biology
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of Regeneration (biology), regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult organism. Perspectives The main processes involved in the embryogenesis, embryonic development of animals are: tissue patterning (via regional specification and patterned cellular differentiation, cell differentiation); tissue growth; and tissue morphogenesis. * Regional specification refers to the processes that create the spatial patterns in a ball or sheet of initially similar cells. This generally involves the action of cytoplasmic determinants, located within parts of the fertilized egg, and of inductive signals emitted from signaling centers in the embryo. The early stages of regional specification do not generate functional differentiated cells, but cell populations committed to developing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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