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Matthias Jacob Schleiden (1804–1881) [1]
Published on The Embryo Project Encyclopedia (https://embryo.asu.edu) Matthias Jacob Schleiden (1804–1881) [1] By: Parker, Sara Keywords: cells [2] Matthias Jacob Schleiden helped develop the cell theory in Germany during the nineteenth century. Schleiden studied cells as the common element among all plants and animals. Schleiden contributed to the field of embryology [3] through his introduction of the Zeiss [4] microscope [5] lens and via his work with cells and cell theory as an organizing principle of biology. Schleiden was born in Hamburg, Germany, on 5 April 1804. His father was the municipal physician of Hamburg. Schleiden pursued legal studies at the University of Heidelberg [6] in Heidelberg, Germany, and he graduated in 1827. He established a legal practice in Hamburg, but after a period of emotional depression and an attempted suicide, he changed professions. He studied natural science at the University of Göttingen in Göttingen, Germany, but transferred to the University of Berlin [7] in Berlin, Germany, in 1835 to study plants. Johann Horkel, Schleiden's uncle, encouraged him to study plant embryology [3]. In Berlin, Schleiden worked in the laboratory of zoologistJ ohannes Müller [8], where he met Theodor Schwann. Both Schleiden and Schwann studied cell theory and phytogenesis, the origin and developmental history of plants. They aimed to find a unit of organisms common to the animal and plant kingdoms. They began a collaboration, and later scientists often called Schleiden and Schwann the founders of cell theory. In 1838, Schleiden published "Beiträge zur Phytogenesis" (Contributions to Our Knowledge of Phytogenesis). The article outlined his theories of the roles cells played as plants developed. -
Sahel Journal of Veterinary Sciences
Original Article Sahel Journal of Veterinary Sciences Article History Received: 4th March, 2020 Sahel J. Vet. Sci. Vol. 17, No. 2, pp. 19-25 (2020) Revised: 3rd June, 2020 Copyright © 2020 Faculty of Veterinary Medicine, University of Maiduguri Accepted: 7th June, 2020 All rights reserved Published: 30th June, 2020 Structure of the Leydig Cell in the African Sideneck Turtle (Pelusios castaneus) Olukole, S. G. and Oke, B. O. Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Nigeria. * Author for Correspondence: [email protected]; +2348033574752 Abstract The African sideneck turtle (Pelusios castaneus) is a freshwater turtle of West African origin used in traditional medicine with little consumption as meat. There have been documentations on the reproductive biology of the turtle with no report on the structure of the Leydig cell of the animal. We described the structure of the Leydig cell of the adult African sideneck turtle using histology, microstereology and transmission electron microscopy. The Leydig cell of the African sideneck turtle were elliptical in shape when found proximal to blood vessels and elongated at other points within the testicular interstitium. Leydig cells occurred in cords or clusters of varying sizes and numbers (3-5 cells) that appear to be random in distribution possessing round to ovoid nuclei containing small amount of peripherally disposed heterochromatin with prominent nucleoli. The seminiferous tubules of the turtle occupied about 85% of the total testicular parenchyma while the interstitium occupied 15% of it. Of this 15%, the Leydig cell occupied about 10% while the stromal elements, inclusive of blood vessels occupied the remaining 5%. -
Catholic Christian Christian
Religious Scientists (From the Vatican Observatory Website) https://www.vofoundation.org/faith-and-science/religious-scientists/ Many scientists are religious people—men and women of faith—believers in God. This section features some of the religious scientists who appear in different entries on these Faith and Science pages. Some of these scientists are well-known, others less so. Many are Catholic, many are not. Most are Christian, but some are not. Some of these scientists of faith have lived saintly lives. Many scientists who are faith-full tend to describe science as an effort to understand the works of God and thus to grow closer to God. Quite a few describe their work in science almost as a duty they have to seek to improve the lives of their fellow human beings through greater understanding of the world around them. But the people featured here are featured because they are scientists, not because they are saints (even when they are, in fact, saints). Scientists tend to be creative, independent-minded and confident of their ideas. We also maintain a longer listing of scientists of faith who may or may not be discussed on these Faith and Science pages—click here for that listing. Agnesi, Maria Gaetana (1718-1799) Catholic Christian A child prodigy who obtained education and acclaim for her abilities in math and physics, as well as support from Pope Benedict XIV, Agnesi would write an early calculus textbook. She later abandoned her work in mathematics and physics and chose a life of service to those in need. Click here for Vatican Observatory Faith and Science entries about Maria Gaetana Agnesi. -
The Physiology and Immunology of the Endocrine Testis
tì/ jì;:llilul s\ t: 1.q_ 81 LI Àt{Y THE PHYSIOLOGY AND IMMUNOLOGY OF THE ENDOCRINE TESTIS by Simon MADDOCKS, B.Ag.Scl. (Hons) A thesls submltted to the Unlversfty of Adelalde ln fulfl'lment of the requlrements for the degree of Doctor of PhllosoPhY Department of Anlmal Scfences Walte Agrlcultural Research Instltute The UnlversitY of Adelalde March 1987 lì,.,ì,r(,:,td r/ riÈ"1 Know'ledge and wlsdom far f rom belng oner. Have ofl tlmes no connexion. Knorledge dwells In heads replete with thoughts of other men; Wlsdom ln minds attentlve to thelr otvn' Know'ledger a rude unprof ltab'le massr The meré materials with whlch wlsdom bul'ldsr Tfl.|smoothldandsquarldandflttedtoftsplacer Does but encumber whom lt seems trenrlch' Knowledge ls proud that he has learnrd so much; Wisdom ls humb'le that he knows no more' I{il'l lam CowPer ( 1731-1800) '_ .å Cowper Poetical Works TABLE OF CONTENTS f CONTENTS vii ABSTRACT x DECLARATION xl ACKNOt{LEDGEMENTS PREFACE xlff PART I: T CTIAPTER I: INTRODUCTION 2 1. 1. INTRODUCTION 2 L.2, THE PHYSIOLOGY OF THE ENDOCRINE TESTIS L.2,L. Introducti on 2 L.2.2. The Leydfg cells 7 r.2,2. I, Anatomy 7 L.2.2. 2. Relatiónship to blood vessels, lymph vessels and seminiferous tubul es L2 .2.2 3, Re]atfonshlp to other ce]ls in fnterstlt'lal tissue I5 I 18 ,212 4. Hormones produced by the Leydfg ce1ìs I 22 L .2.3 The Sertoll cells 24 T .2,3 I. AnatomY I .2.3 2. -
Birdobserver17.4 Page183-188 an Honor Without Profit Richard K
AN HONOR WITHOUT PROFIT by Richard K. Walton eponymy n The derivation of a name of a city, country, era, institution, or other place or thing from the name of a person. Gruson in his Words for Birds gives seven categories for the origins of common bird names: appearance (Black-capped Chickadee), eponymy (Henslow’s Sparrow), echoics (Whooping Crane), habitat (Marsh Wren), behavior (woodpecker), food (oystercatcher), and region (California Condor). The second category comprises people and places memorialized in bird names. Many of our most famous ornithologists as well as a fair number of obscure friends and relations have been so honored. A majority of these names were given during the eighteenth and nineteenth centuries, the pioneering era of North American ornithology. While some of these tributes are kept alive in our everyday birding language, others have slipped into oblivion. Recognition or obscurity may ultimately hinge on the names we use for birds. There is no more famous name in the birding culture than that of John James Audubon. His epic The Birds of America was responsible for putting American science, art, and even literature on the international map. This work was created, produced, promoted, and sold largely by Audubon himself. In the years since his death in 1851, the Audubon legend has been the inspiration for a multitude of ornithological pursuits and causes, both professional and amateur. Audubon painted some five hundred birds in Birds of America and described these in his five-volume Ornithological Biographies. Many of the names given by Audubon honored men and women of his era. -
Review Effects of Thyroid Hormones on Leydig Cells in the Postnatal Testis
Histol Histopathol (2004) 19: 985-997 Histology and http://www.hh.um.es Histopathology Cellular and Molecular Biology Review Effects of thyroid hormones on Leydig cells in the postnatal testis S.M.L.C. Mendis-Handagama and H.B.S. Ariyaratne* Department of Comparative Medicine, The University of Tennessee College of Veterinary Medicine, Knoxville, TN, USA *Present address: Department of Veterinary Basic Sciences, Faculty of Veterinary Medicine & Animal Science, University of Peradeniya, Sri Lanka Summary. Thyroid hormones (TH) stimulate oxidative Key words: Thyroid hormone, Leydig cells, Stem cell metabolism in many tissues in the body, but testis is not differentiation, Leydig progenitor cells, Steroidogenesis, one of them. Therefore, in this sense, testis is not Aging considered as a target organ for TH. However, recent findings clearly show that TH have significant functions on the testis in general, and Leydig cells in particular; Introduction this begins from the onset of their differentiation through aging. Some of these functions include triggering the Leydig cells are the main source of androgens in the Leydig stem cells to differentiate, producing increased mammalian male. In this paper, efforts have been made numbers of Leydig cells during differentiation by to review the available literature on TH on Leydig cells causing proliferation of Leydig stem cells and in the postnatal testis. progenitors, stimulation of the Leydig cell steroidogenic function and cellular maintenance. The mechanism of Leydig Cells action of TH on Leydig cell differentiation is still not clear and needs to be determined in future studies. Franz Leydig, a scientist from Germany, first However, some information on the mechanisms of TH described the Leydig cells in the testis interstitium in action on Leydig cell steroidogenesis is available. -
(Evolution) Prior to Darwin's Origin of Species
Theories of Species Change (Evolution) Prior to Darwin’s Origin of Species Theories of Species Change Prior to Darwin Entangled with: 1. Theories of geological change. 2. Theories of heredity. 3. And theories of ontogenesis, that is, of individual development– embryology. Notions of Species in the Classical Period of Greece Plato: the essence or form of an organism is eternal and unchanging; embodiment only the appearance of that form. Aristotle: the essence or form of an organism is incorporated in the physical body; the only kind of eternity enjoyed is through continued reproduction. Theories of Species Change in the Early Modern Period Descartes: gradual evolution of physical system according to fix laws (Discourse on Method, 1628). Buffon (1707-88) and Linnaeus (1707-78): God created a limited number of species, but through hybridization and impact of environment, new species appear. Kant: evolutionary development from earth possible only if earth already construed as purposive; species change possible but no evidence (Critique of Judgment, 1790). Transformation of one species into another through change of scaling, from D’Arcy Thompson, On Growth and Form (1942). Carus’s illustration of the Richard Owen’s illustration of the archetype archetype, from his On the Nature of Limbs (1849) Georges Cuvier (1769-1832). Portrait by François-André Vincent Adam’s Mammoth, found in Siberia in 18th century; St. Petersburg Natural History Museum Cuvier’s illustration of the Siberian mammoth; he identified it as an extinct species of elephant (1796). Cuvier’s illustration of the “Ohio Animal,” which he named “mastodon.” Megatherium (i.e., “large animal”), discovered in South America, described by Cuvier as an extinct creature similar to the modern sloth. -
Complicated Meckel's Diverticulum and Therapeutic Management
Ulusal Cer Derg 2013; 29: 63-66 Original Investigation DOI: 10.5152/UCD.2013.36 Complicated Meckel's diverticulum and therapeutic management Varlık Erol, Tayfun Yoldaş, Samet Cin, Cemil Çalışkan, Erhan Akgün, Mustafa Korkut Objective: This study aimed to investigate the treatment options and compare patient management with the litera- ABSTRACT ture for patients operated on for an acute abdomen who had complications due to inflammation of the Meckel’s diverticulum at our clinics. Material and Methods: This study retrospectively evaluated 14 patients who had been operated on for acute abdo- men and had been diagnosed with Meckel’s diverticulitis (MD) in Ege University Medical Faculty Department of General Surgery, between October 2007 and October 2012. Results: Fourteen patients with a diagnosis of Meckel’s diverticulitis (MD) were retrospectively analyzed. Radiologi- cally, the abdominal computer tomography showed pathologies compatible with mechanical intestinal obstruction, Meckel’s diverticulitis and peridiverticular abscess, as well as detection of free air within the abdomen on direct abdominal X-ray. Among patients diagnosed with complicated Meckel’s diverticuli (obstruction, diverticulitis, perfo- ration) 10 patients had partial small bowel resection and end-to-end anastomosis (71.5%), three patients underwent diverticulum excision (21.4%), and one patient underwent right hemicolectomy+ileotransversostomy (7.1%). Conclusion: Meckel’s diverticulum is a vestigial remnant of an omphalomesenteric channel in the small bowel. It is a real congenital diverticular abnormality that contains all three layers of the small bowel. Surgical excision should be performed if Meckel’s diverticulum is detected in order to avoid incidental complications such as ulcer- ation, bleeding, bowel obstruction, diverticulitis or perforation. -
Biological Atomism and Cell Theory
Studies in History and Philosophy of Biological and Biomedical Sciences 41 (2010) 202–211 Contents lists available at ScienceDirect Studies in History and Philosophy of Biological and Biomedical Sciences journal homepage: www.elsevier.com/locate/shpsc Biological atomism and cell theory Daniel J. Nicholson ESRC Research Centre for Genomics in Society (Egenis), University of Exeter, Byrne House, St. Germans Road, Exeter EX4 4PJ, UK article info abstract Keywords: Biological atomism postulates that all life is composed of elementary and indivisible vital units. The activ- Biological atomism ity of a living organism is thus conceived as the result of the activities and interactions of its elementary Cell theory constituents, each of which individually already exhibits all the attributes proper to life. This paper sur- Organismal theory veys some of the key episodes in the history of biological atomism, and situates cell theory within this Reductionism tradition. The atomistic foundations of cell theory are subsequently dissected and discussed, together with the theory’s conceptual development and eventual consolidation. This paper then examines the major criticisms that have been waged against cell theory, and argues that these too can be interpreted through the prism of biological atomism as attempts to relocate the true biological atom away from the cell to a level of organization above or below it. Overall, biological atomism provides a useful perspective through which to examine the history and philosophy of cell theory, and it also opens up a new way of thinking about the epistemic decomposition of living organisms that significantly departs from the phys- icochemical reductionism of mechanistic biology. -
Behavioral Ecology and Sociobiology in Post-Truth Society
Behav Ecol Sociobiol (2017) 71:76 DOI 10.1007/s00265-017-2303-7 EDITORIAL Behavioral ecology and sociobiology in post-truth society James F. A. Traniello1 & Theo C. M. Bakker2 # Springer-Verlag Berlin Heidelberg 2017 William Whewell (1833)coinedthetermscientist to describe the falsehoods and hoaxes that have virtually become every- experts in the study of natural phenomena. BNature,^ he day occurrences. Although the study of climate change has wrote, Bis a collection of facts governed by laws….To ascer- been the target of most high-profile assaults, skepticism is not tain such laws of nature is the peculiar business of science.^ restricted to atmospheric science or limited to specific research Today, scientists practice in a post-truth society in which trou- agendas. Online journalists attempt to throw truth and reality bling, and often disturbing, attitudes toward science have be- into question and undermine all science by challenging the come commonplace. Science is being marginalized and sup- peer review process. This attack on how ideas are critically pressed (Vernon 2017). Concerns are raised about risks of evaluated, how data are validated, and the nature of proof is human endangerment resulting from the disregard of science insidious. (Gross 2017). Parallels are drawn between the dissemination What should behavioral ecologists do in the present social andgrowthofBfake news^ and the spread of disease environment of denialism? How should we respond to science (Kucharski 2016). Higgins (2016) sounds the alarm: Blosing its relevance as a source of truth^ (Makri 2017)? The BScientists … should be shocked by the idea of post-truth, answer is that we should preach what we practice in a unified … speak up when scientific findings are ignored,… keep voice that is loud and clear. -
Scientific BIOGRAPHY and the CASE of GEORGES CUVIER
Hist. Sci.) xiv (1976), 101-137 1976HisSc..14..101O SCIENTIFic BIOGRAPHY AND THE CASE OF GEORGES CUVIER: WITH A CRITICAL BIBLIOGRAPHY Dorinda OutralU University of Reading The purpose of this introduction is to provide some interpretative tools for the reader of the body of secondary literature on Georges Cuvier which is examined in the attached critical bibliography. Criticism and analysis of existing work is therefore emphasized, and the problems in volved in constructing a positive biography of Cuvier are only briefly examined. Not only strictly biographical studies, but also work on all aspects of Cuvier's achievement, have been so strongly informed by pre suppositions about his character, that a knowledge of this bias and its characteristic expressions is nece.<;sary before previous work on Cuvier can be properly interp'reted. This bibliography is thus also intended as a necessary clearing of the ground before further study of Cuvier's career can be undertaken. This is true not only because it is necessary to discover the precise extent of factual inadequacy in our knowledge of Cuvier's life and achievement, but also because we need to increase our awareness of the role which biographical inquiry has played in the history of science, for without this awareness, the full implications of the adoption of the form cannot be assessed. Interest in Georges Cuvier has increased considerably during the last decade, but so far almost no account has been taken of the extraordinary biographical tradition through which we view him. Almost every presen tation of Cuvier since his death in 1832 has been dominated by emphases which were established very soon afterwards, and which have continued to monopolize the attention of historians of the life-sciences until very recently. -
Arts Et Savoirs, 9 | 2018 L’Âme Cellulaire Et L’Ésotérisme Moderne De Haeckel 2
Arts et Savoirs 9 | 2018 Ernst Haeckel entre science et esthétique L’âme cellulaire et l’ésotérisme moderne de Haeckel Robert Matthias Erdbeer Traducteur : Julie Mottet et Henning Hufnagel Édition électronique URL : http://journals.openedition.org/aes/1193 DOI : 10.4000/aes.1193 ISSN : 2258-093X Éditeur Laboratoire LISAA Référence électronique Robert Matthias Erdbeer, « L’âme cellulaire et l’ésotérisme moderne de Haeckel », Arts et Savoirs [En ligne], 9 | 2018, mis en ligne le 14 mai 2018, consulté le 02 mai 2019. URL : http:// journals.openedition.org/aes/1193 ; DOI : 10.4000/aes.1193 Ce document a été généré automatiquement le 2 mai 2019. Centre de recherche LISAA (Littératures SAvoirs et Arts) L’âme cellulaire et l’ésotérisme moderne de Haeckel 1 L’âme cellulaire et l’ésotérisme moderne de Haeckel Robert Matthias Erdbeer Traduction : Julie Mottet et Henning Hufnagel NOTE DE L'AUTEUR Cet article est une version française du texte „Die ‚Erhaltung der Fühlung’. Haeckels Seelenzellen und der Stil der Esoterischen Moderne“ paru dans Lendemains. Études comparées sur la France, t. 41, n° 162-163, 2016, p. 100-123 (version en ligne : URL : http:// periodicals.narr.de/index.php/Lendemains/article/view/2939). Traduction de l’allemand par Julie Mottet et Henning Hufnagel En somme c’est le malheur du savoir de nos jours que tout vise si terriblement à la grandiloquence.1 Sören Kierkegaard, Le Concept de l’angoisse. De la science à la para-science ésotérique Arts et Savoirs, 9 | 2018 L’âme cellulaire et l’ésotérisme moderne de Haeckel 2 1 La modernité ésotérique est le pendant de « l’ère des sciences naturelles ».