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Louis-Antoine Ranvier
Louis-Antoine Ranvier (2 October 1835 – 22 March 1922) was a French physician, pathologist, anatomist and histologist, who discovered the nodes of Ranvier, regularly spaced discontinuities of the myelin sheath, occurring at varying intervals along the length of a nerve fiber. Career Ranvier was born and studied medicine at Lyon, graduating in 1865 from the Ecole Préparatoire de Médecine et de Pharmacie. He moved to Paris after receiving the internship of Parisian hospitals. Here he founded a small private research laboratory on Rue Christine along with fellow intern Victor André Cornil, and together they later offered a course in histology to medical students which involved the careful examination of tissues under a microscope. Their course was unique in the time as microscopy had not been viewed favourably in medicine especially by Henri Ducrotay de Blainville (1777-1850) and Auguste Comte (1798-1857). Their histology course material became an influential textbook on histo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyon
Lyon,, ; Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the third-largest city and second-largest metropolitan area of France. It is located at the confluence of the rivers Rhône and Saône, to the northwest of the French Alps, southeast of Paris, north of Marseille, southwest of Geneva, northeast of Saint-Étienne. The City of Lyon proper had a population of 522,969 in 2019 within its small municipal territory of , but together with its suburbs and exurbs the Lyon metropolitan area had a population of 2,280,845 that same year, the second most populated in France. Lyon and 58 suburban municipalities have formed since 2015 the Metropolis of Lyon, a directly elected metropolitan authority now in charge of most urban issues, with a population of 1,411,571 in 2019. Lyon is the prefecture of the Auvergne-Rhône-Alpes region and seat of the Departmental Council of Rhône (whose jurisdiction, however, no longer extends over the Metropolis of Lyo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auguste Comte
Isidore Marie Auguste François Xavier Comte (; 19 January 1798 – 5 September 1857) was a French philosopher and writer who formulated the doctrine of positivism. He is often regarded as the first philosopher of science in the modern sense of the term. Comte's ideas were also fundamental to the development of sociology; indeed, he invented the term and treated that discipline as the crowning achievement of the sciences. Influenced by Henri de Saint-Simon, Comte's work attempted to remedy the social disorder caused by the French Revolution, which he believed indicated imminent transition to a new form of society. He sought to establish a new social doctrine based on science, which he labelled 'positivism'. He had a major impact on 19th-century thought, influencing the work of social thinkers such as John Stuart Mill and George Eliot. His concept of ''Sociologie'' and social evolutionism set the tone for early social theorists and anthropologists such as Harriet Martineau an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph-Louis Renaut
Joseph-Louis Renaut (7 December 1844 – 26 December 1917) was a French physician, anatomist, and histologist. A student of Louis-Antoine Ranvier, he served as professor of anatomy and histology at the faculty of medicine in Lyons. Renaut bodies or corpuscles found in nerve tissue are named after him. Renaut was born in La Haye-Descartes, Indre-et-Loire, and studied medicine from 1864, first at Tours and then in Paris. In 1869 he became an interne des hôpitaux and continued to study under Victor André Cornil and Louis-Antoine Ranvier. In 1874 he submitted a thesis on erysipelas Erysipelas () is a relatively common bacterial infection of the superficial layer of the skin ( upper dermis), extending to the superficial lymphatic vessels within the skin, characterized by a raised, well-defined, tender, bright red rash, t ... and earned two medal in 1876 and then became director of the pathology laboratory at the Charité Hospital, Paris. In 1877 he became head of anatomy and h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luis Simarro Lacabra
Luis Simarro Lacabra (6 January 1851 – 19 June 1921) was a Spanish neurologist who was born in Rome while his parents were living in Italy. Career He studied medicine in Valencia and Madrid, and in 1877 was appointed director of the Santa Isabel insane asylum at Leganés, outside of Madrid. From 1880 he lived in Paris and studied general anatomy and histology with Louis-Antoine Ranvier and clinical neurology under Jean Martin Charcot. Here he also came under the influence of philosopher Ernest Renan (1823–1892). anatomist Mathias-Marie Duval (1844–1907) and psychiatrist Valentin Magnan (1835–1916). In 1885 he returned to Madrid and opened a private practice, and in 1902 was appointed to the first chair of experimental psychology in Spain. As a psychiatrist, Simarro was heavily influenced by developments in Germany, particularly Emil Kraepelin's classification and treatment of the insane, Wilhelm Wundt's theory of experimental psychology and Theodor Ziehen's critical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Justin Marie Jolly
Justin Marie Jolly (August 6, 1870 – February 1, 1953) was a French hematologist and histologist born in Melun, Seine-et-Marne. He was a pioneer in the field of hematology as it pertained to the study of living tissue. He studied medicine at the Collège de France under Louis-Antoine Ranvier (1835-1922) and Louis-Charles Malassez (1842-1909) where he learned histological techniques and their correlation to other medical disciplines. He was ''chef du laboratoire'' at the medical clinic in the Hôtel-Dieu de Paris, and director of the histological laboratory at the École des Hautes Etudes. From 1925 to 1940 he was a professor at the Collège de France. In the early part of the 20th century he produced the earliest films of mitosis in living cells via "microscopic movies". In 1923 he published an influential textbook on hematology called ''Traité technique d'hématologie''. Along with American physiologist William Henry Howell (1860-1945), the Howell-Jolly bodies are named; w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensory Nerve
A sensory nerve, or afferent nerve, is a general anatomic term for a nerve which contains predominantly somatic afferent nerve fibers. Afferent nerve fibers in a sensory nerve carry sensory information toward the central nervous system (CNS) from different sensory receptors of sensory neurons in the peripheral nervous system. A motor nerve carries information from the CNS to the PNS, and both types of nerve are called peripheral nerves. Afferent nerve fibers link the sensory neurons throughout the body, in pathways to the relevant processing circuits in the central nervous system. Afferent nerve fibers are often paired with efferent nerve fibers from the motor neurons (that travel from the CNS to the PNS), in mixed nerves. Stimuli cause nerve impulses in the receptors and alter the potentials, which is known as sensory transduction. Spinal cord entry Afferent nerve fibers leave the sensory neuron from the dorsal root ganglia of the spinal cord, and motor commands carried ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catecholamine
A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol (benzene with two hydroxyl side groups next to each other) and a side-chain amine. Catechol can be either a free molecule or a substituent of a larger molecule, where it represents a 1,2-dihydroxybenzene group. Catecholamines are derived from the amino acid tyrosine, which is derived from dietary sources as well as synthesis from phenylalanine. Catecholamines are water-soluble and are 50% bound to plasma proteins in circulation. Included among catecholamines are epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine. Release of the hormones epinephrine and norepinephrine from the adrenal medulla of the adrenal glands is part of the fight-or-flight response. Tyrosine is created from phenylalanine by hydroxylation by the enzyme phenylalanine hydroxylase. Tyrosine is also ingested directly from dietary protein. Catecholamine-secreting cells use sev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epidermis (skin)
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water released from the body into the atmosphere through transepidermal water loss. The epidermis is composed of multiple layers of flattened cells that overlie a base layer (stratum basale) composed of columnar cells arranged perpendicularly. The layers of cells develop from stem cells in the basal layer. The human epidermis is a familiar example of epithelium, particularly a stratified squamous epithelium. The word epidermis is derived through Latin , itself and . Something related to or part of the epidermis is termed epidermal. Structure Cellular components The epidermis primarily consists of keratinocytes ( proliferating basal and differentiated suprabasal), which comprise 90% of its cells, but also contains melanocytes, Langerhans c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratum Germinativum
The ''stratum basale'' (basal layer, sometimes referred to as ''stratum germinativum'') is the deepest layer of the five layers of the epidermis, the external covering of skin in mammals. The ''stratum basale'' is a single layer of columnar or cuboidal basal cells. The cells are attached to each other and to the overlying stratum spinosum cells by desmosomes and hemidesmosomes. The nucleus is large, ovoid and occupies most of the cell. Some basal cells can act like stem cells with the ability to divide and produce new cells, and these are sometimes called basal keratinocyte stem cells. Others serve to anchor the epidermis glabrous skin (hairless), and hyper-proliferative epidermis (from a skin disease).McGrath, J.A.; Eady, R.A.; Pope, F.M. (2004). ''Rook's Textbook of Dermatology'' (Seventh Edition). Blackwell Publishing. Pages 3.7. . They divide to form the keratinocytes of the stratum spinosum, which migrate superficially. Other types of cells found within the ''stratum bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanocyte
Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and heart. Melanin is a dark pigment primarily responsible for skin color. Once synthesized, melanin is contained in special organelles called melanosomes which can be transported to nearby keratinocytes to induce pigmentation. Thus darker skin tones have more melanosomes present than lighter skin tones. Functionally, melanin serves as protection against UV radiation. Melanocytes also have a role in the immune system. Function Through a process called melanogenesis, melanocytes produce melanin, which is a pigment found in the skin, eyes, hair, nasal cavity, and inner ear. This melanogenesis leads to a long-lasting pigmentation, which is in contrast to the pigmentation that originates from oxidation of already-existing melanin. There are both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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