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Limbal Stem Cell
Limbal stem cells, also known as corneal epithelial stem cells, are stem cells located in the basal epithelial layer of the corneal limbus. They form the border between the cornea and the sclera. Characteristics of limbal stem cells include a slow turnover rate, high proliferative potential, clonogenicity, expression of stem cell markers, as well as the ability to regenerate the entire corneal epithelium. Limbal stem cell proliferation has the role of maintaining the cornea; for example, by replacing cells that are lost via tears. Additionally, these cells also prevent the conjunctival epithelial cells from migrating onto the surface of the cornea. Medical conditions and treatments Damage to the limbus can lead to limbal stem cell deficiency (LSCD); this may be primary - related to an insufficient stromal microenvironment to support stem cell functions, such as aniridia, and other congenital conditions, or secondary – caused by external factors that destroy the limbal stem cells, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem Cells
In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell in a cell lineage. They are found in both embryonic and adult organisms, but they have slightly different properties in each. They are usually distinguished from progenitor cells, which cannot divide indefinitely, and precursor or blast cells, which are usually committed to differentiating into one cell type. In mammals, roughly 50–150 cells make up the inner cell mass during the blastocyst stage of embryonic development, around days 5–14. These have stem-cell capability. ''In vivo'', they eventually differentiate into all of the body's cell types (making them pluripotent). This process starts with the differentiation into the three germ layers – the ectoderm, mesoderm and endoderm – at the gastrulation stage. However, when ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corneal Limbus
The corneal limbus (''Latin'': corneal border) is the border between the cornea and the sclera (the white of the eye). It contains stem cells in its palisades of Vogt. It may be affected by cancer or by aniridia (a developmental problem), among other issues. Structure The corneal limbus is the border between the cornea and the sclera. It is highly vascularised. Its stratified squamous epithelium is continuous with the epithelium covering the cornea. The corneal limbus contains radially-oriented fibrovascular ridges known as the palisades of Vogt that contain stem cells. The palisades of Vogt are more common in the superior and inferior quadrants around the eye. Clinical significance Cancer The corneal limbus is a common site for the occurrence of corneal epithelial neoplasm. Aniridia Aniridia, a developmental anomaly of the iris, disrupts the normal barrier of the cornea to the conjunctival epithelial cells at the limbus. Glaucoma The corneal limbus may be c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sclera
The sclera, also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some crucial elastic fiber. In humans, and some other vertebrates, the whole sclera is white, contrasting with the coloured iris, but in most mammals, the visible part of the sclera matches the colour of the iris, so the white part does not normally show while other vertebrates have distinct colors for both of them. In the development of the embryo, the sclera is derived from the neural crest. In children, it is thinner and shows some of the underlying pigment, appearing slightly blue. In the elderly, fatty deposits on the sclera can make it appear slightly yellow. People with dark skin can have naturally darkened sclerae, the result of melanin pigmentation. The human eye is relatively rare for having a pale sclera (relative to the iris). This makes it easier for one individual to ide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is approximately 43 dioptres. The cornea can be reshaped by surgical procedures such as LASIK. While the cornea contributes most of the eye's focusing power, its focus is fixed. Accommodation (the refocusing of light to better view near objects) is accomplished by changing the geometry of the lens. Medical terms related to the cornea often start with the prefix "'' kerat-''" from the Greek word κέρας, ''horn''. Structure The cornea has unmyelinated nerve endings sensitive to touch, temperature and chemicals; a touch of the cornea causes an involuntary reflex to close the eyelid. Because transparency is of prime importance, the healthy cornea does not have or need blood vessels with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tears
Tears are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all land mammals. Tears are made up of water, electrolytes, proteins, lipids, and mucins that form layers on the surface of eyes. The different types of tears—basal, reflex, and emotional—vary significantly in composition. The functions of tears include lubricating the eyes (basal tears), removing irritants (reflex tears), and also aiding the immune system. Tears also occur as a part of the body's natural pain response. Emotional secretion of tears may serve a biological function by excreting stress-inducing hormones built up through times of emotional distress. Tears have symbolic significance among humans. Physiology Chemical composition Tears are made up of three layers: lipid, aqueous, and mucous. Tears are composed of water, salts, antibodies, and lysozymes (antibacterial enzymes); though composition varies among different tear types. The composition of tears caused by an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjunctiva
The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium and stratified cuboidal epithelium (depending on the zone). The conjunctiva is highly vascularised, with many microvessels easily accessible for imaging studies. Structure The conjunctiva is typically divided into three parts: Blood supply Blood to the bulbar conjunctiva is primarily derived from the ophthalmic artery. The blood supply to the palpebral conjunctiva (the eyelid) is derived from the external carotid artery. However, the circulations of the bulbar conjunctiva and palpebral conjunctiva are linked, so both bulbar conjunctival and palpebral conjunctival vessels are supplied by both the ophthalmic artery and the external carotid artery, to varying extents. Nerve supply Sensory innervation of the conjunctiva is divided into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corneal Epithelium
The corneal epithelium (epithelium corneæ anterior layer) is made up of epithelial tissue and covers the front of the cornea. It acts as a barrier to protect the cornea, resisting the free flow of fluids from the tears, and prevents bacteria from entering the epithelium and corneal stroma. Anatomy The corneal epithelium consists of several layers of cells. The cells of the deepest layer are columnar, known as basal cells which are attached by multiprotein complexes known as hemidesmosomes to an underlying basement membrane. Then follow two or three layers of polyhedral cells, commonly known as wing cells. The majority of these are prickle cells, similar to those found in the stratum mucosum of the cuticle. Lastly, there are three or four layers of squamous cells, with flattened nuclei. The layers of the epithelium are constantly undergoing mitosis. Basal and wing cells migrate to the anterior of the cornea, while squamous cells age and slough off into the tear film. Central ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Commission
The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body of about 32,000 European civil servants. The Commission is divided into departments known as Directorates-General (DGs) that can be likened to departments or ministries each headed by a Director-General who is responsible to a Commissioner. There is one member per member state, but members are bound by their oath of office to represent the general interest of the EU as a whole rather than their home state. The Commission President (currently Ursula von der Leyen) is proposed by the European Council (the 27 heads of state/governments) and elected by the European Parliament. The Council of the European Union then nominates the other members of the Commission in agreement with the nominated President, and the 27 members as a team are then ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem Cell Therapy
Stem-cell therapy is the use of stem cells to treat or prevent a disease or condition. , the only established therapy using stem cells is hematopoietic stem cell transplantation. This usually takes the form of a bone-marrow transplantation, but the cells can also be derived from umbilical cord blood. Research is underway to develop various sources for stem cells as well as to apply stem-cell treatments for neurodegenerative diseases and conditions such as diabetes and heart disease. Stem-cell therapy has become controversial following developments such as the ability of scientists to isolate and culture embryonic stem cells, to create stem cells using somatic cell nuclear transfer and their use of techniques to create induced pluripotent stem cells. This controversy is often related to abortion politics and to human cloning. Additionally, efforts to market treatments based on transplant of stored umbilical cord blood have been controversial. Medical uses For over 30 year ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Medicines Agency
The European Medicines Agency (EMA) is an agency of the European Union (EU) in charge of the evaluation and supervision of medicinal products. Prior to 2004, it was known as the European Agency for the Evaluation of Medicinal Products or European Medicines Evaluation Agency (EMEA).Set up by EC Regulation No. 2309/93 as the European Agency for the Evaluation of Medicinal Products, and renamed by EC Regulation No. 726/2004 to the European Medicines Agency, it had the acronym EMEA until December 2009. The European Medicines Agency does not call itself EMA either – it has no official acronym but may reconsider if EMA becomes commonly accepted (secommunication on new visual identity an). The EMA was set up in 1995, with funding from the European Union and the pharmaceutical industry, as well as indirect subsidy from member states, its stated intention to harmonise (but not replace) the work of existing national medicine regulatory bodies. The hope was that this plan would not onl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graziella Pellegrini
Graziella Pellegrini (born July 12, 1961) is an Italian Professor of Cell Biology and the Cell Therapy Program Coordinator at the University of Modena and Reggio Emilia. She has developed and championed cell therapy protocols in hospitals across Italy. Early life and education Pellegrini was born in Genoa. She studied molecular pharmacology at the University of Genoa, where she earned her PhD in 1988. She continued to study chemistry and pharmacology at the University of Genoa, and completed two subsequent degrees in 1989. Pellegrini completed extra training to become a pharmacist. Research and career Pellegrini was appointed to the Italian National Institute for Cancer Research in 1988. She held positions at Celllife Biotechnology, the Advanced Biotechnology Center and the Veneto Eye Bank Association. She is best known for her work in translational medicine, and has developed epithelial stem cell mediated cell and gene therapies. She has worked with Michele de Luca for most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Human Cell Types Derived From The Germ Layers
This is a list of cells in humans derived from the three embryonic germ layers – ectoderm, mesoderm, and endoderm. Cells derived from ectoderm Surface ectoderm Skin * Trichocyte * Keratinocyte Anterior pituitary * Gonadotrope * Corticotrope * Thyrotrope * Somatotrope * Lactotroph Tooth enamel * Ameloblast Neural crest Peripheral nervous system * Neuron * Glia ** Schwann cell ** Satellite glial cell Neuroendocrine system * Chromaffin cell * Glomus cell Skin * Melanocyte ** Nevus cell * Merkel cell Teeth * Odontoblast * Cementoblast Eyes * Corneal keratocyte Neural tube Central nervous system * Neuron * Glia ** Astrocyte ** Ependymocytes ** Muller glia (retina) ** Oligodendrocyte ** Oligodendrocyte progenitor cell ** Pituicyte (posterior pituitary) Pineal gland * Pinealocyte Cells derived from mesoderm Paraxial mesoderm Mesenchymal stem cell =Osteochondroprogenitor cell= * Bone ( Osteoblast → Osteocyte) * Cartilage (Chondroblast → Chondrocyte) =Myofibroblast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
