|
Neuroepithelial Cell
Neuroepithelial cells, or neuroectodermal cells, form the wall of the closed neural tube in early embryonic development. The neuroepithelial cells span the thickness of the tube's wall, connecting with the pial surface and with the ventricular or lumenal surface. They are joined at the lumen of the tube by junctional complexes, where they form a pseudostratified layer of epithelium called neuroepithelium. Neuroepithelial cells are the stem cells of the central nervous system, known as neural stem cells, and generate the intermediate progenitor cells known as radial glial cells, that differentiate into neurons and glia in the process of neurogenesis. Embryonic neural development Brain development During the third week of embryonic growth the brain begins to develop in the early fetus in a process called morphogenesis. Neuroepithelial cells of the ectoderm begin multiplying rapidly and fold in forming the neural plate, which invaginates during the fourth week of embryonic gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neural Tube
In the developing chordate (including vertebrates), the neural tube is the embryonic precursor to the central nervous system, which is made up of the brain and spinal cord. The neural groove gradually deepens as the neural fold become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into the closed neural tube. In humans, neural tube closure usually occurs by the fourth week of pregnancy (the 28th day after conception). The ectodermal wall of the tube forms the rudiment of the nervous system. The centre of the tube is the ''neural canal''.It is an important structure for the development of fetus's brain and spine Development The neural tube develops in two ways: primary neurulation and secondary neurulation. Primary neurulation divides the ectoderm into three cell types: * The internally located neural tube * The externally located epidermis * The neural crest cells, which develop in the region between the neural tube and epide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Embryogenesis
Human embryonic development, or human embryogenesis, is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, the development of the human body entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell (ovum). The genetic material of the sperm and egg then combine to form the single cell zygote and the germinal stage of development commences. Embryonic development in the human, covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a fetus. Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or 40 weeks. The germinal stage refers to the time from fertilization throu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem Cell Division And Differentiation
Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushroom under the cap * Stem (vine), part of a grapevine * Trunk (botany), the woody stem of a tree Education * Science, technology, engineering, and mathematics (STEM), a broad term used in curricula and policy * STEM.org, an educational publisher and service * Stem, a multiple choice question lede (excluding the options) Language and writing * Word stem, the part of a word common to all its inflected variants ** Stemming, a process in natural language processing * Stem (typography), the main vertical stroke of a letter * Stem (music), a part of a written musical note Man-made objects * Stem (ship), the upright member mounted on the forward end of a vessel's keel, to which the strakes are attached * Stem (bicycle part), connects ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around long in adult men and around long in adult women. The diameter of the spinal cord ranges from in the cervical and lumbar regions to in the thoracic area. The spinal cord functions primarily in the transmission of nerve signals from the motor cortex to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hindbrain
The hindbrain or rhombencephalon or lower brain is a developmental categorization of portions of the central nervous system in vertebrates. It includes the medulla, pons, and cerebellum. Together they support vital bodily processes. Metencephalon Rhombomeres Rh3-Rh1 form the metencephalon. The metencephalon is composed of the pons and the cerebellum; it contains: * a portion of the fourth (IV) ventricle, * the trigeminal nerve (CN V), * abducens nerve (CN VI), * facial nerve (CN VII), * and a portion of the vestibulocochlear nerve (CN VIII). Myelencephalon Rhombomeres Rh8-Rh4 form the myelencephalon. The myelencephalon forms the medulla oblongata in the adult brain; it contains: * a portion of the fourth ventricle, * the glossopharyngeal nerve (CN IX), * vagus nerve (CN X), * accessory nerve (CN XI), * hypoglossal nerve (CN XII), * and a portion of the vestibulocochlear nerve (CN VIII). Evolution The hindbrain is homologous to a part of the arthropod brain known as th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Midbrain
The midbrain or mesencephalon is the forward-most portion of the brainstem and is associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation. The name comes from the Greek ''mesos'', "middle", and ''enkephalos'', "brain". Structure The principal regions of the midbrain are the tectum, the cerebral aqueduct, tegmentum, and the cerebral peduncles. Rostrally the midbrain adjoins the diencephalon (thalamus, hypothalamus, etc.), while caudally it adjoins the hindbrain (pons, medulla and cerebellum). In the rostral direction, the midbrain noticeably splays laterally. Sectioning of the midbrain is usually performed axially, at one of two levels – that of the superior colliculi, or that of the inferior colliculi. One common technique for remembering the structures of the midbrain involves visualizing these cross-sections (especially at the level of the superior colliculi) as the upside-down face of a b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forebrain
In the anatomy of the brain of vertebrates, the forebrain or prosencephalon is the rostral (forward-most) portion of the brain. The forebrain (prosencephalon), the midbrain (mesencephalon), and hindbrain (rhombencephalon) are the three primary brain vesicles during the early development of the nervous system. The forebrain controls body temperature, reproductive functions, eating, sleeping, and the display of emotions. At the five-vesicle stage, the forebrain separates into the diencephalon (thalamus, hypothalamus, subthalamus, and epithalamus) and the telencephalon which develops into the cerebrum. The cerebrum consists of the cerebral cortex, underlying white matter, and the basal ganglia. In humans, by 5 weeks in utero it is visible as a single portion toward the front of the fetus. At 8 weeks in utero, the forebrain splits into the left and right cerebral hemispheres. When the embryonic forebrain fails to divide the brain into two lobes, it results in a condition known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basal Lamina
The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often incorrectly referred to as the basement membrane, though it does constitute a portion of the basement membrane. The basal lamina is visible only with the electron microscope, where it appears as an electron-dense layer that is 20–100 nm thick (with some exceptions that are thicker, such as basal lamina in lung alveoli and renal glomeruli). Structure The layers of the basal lamina ("BL") and those of the basement membrane ("BM") are described below: Anchoring fibrils composed of type VII collagen extend from the basal lamina into the underlying reticular lamina and loop around collagen bundles. Although found beneath all basal laminae, they are especially numerous in stratified squamous cells of the skin. These layers should not be confused with the lamina propria, which is found outside the basal lamina. Basement membrane The basement membran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integrin Alpha 6
Integrin alpha-6 is a protein that in humans is encoded by the ''ITGA6'' gene. Function The ITGA6 protein product is the integrin alpha chain alpha 6. Integrins are integral cell-surface proteins composed of an alpha chain and a beta chain. A given chain may combine with multiple partners resulting in different integrins. For example, alpha 6 may combine with beta 4 in the integrin referred to as TSP180, or with beta 1 in the integrin VLA-6. Integrins are known to participate in cell adhesion as well as cell-surface mediated signalling. Two transcript variants encoding different isoforms have been found for this gene. Specific loss of this integrin chain in the intestinal epithelium, and thus of their hemidesmosomes, induces long-standing colitis and infiltrating adenocarcinomas. Interactions ITGA6 has been shown to interact with TSPAN4 and GIPC1. See also * Cluster of differentiation * Integrin Integrins are transmembrane receptors that facilitate cell-cell and cell-e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tight Junctions
Tight junctions, also known as occluding junctions or ''zonulae occludentes'' (singular, ''zonula occludens''), are multiprotein junctional complexes whose canonical function is to prevent leakage of solutes and water and seals between the epithelial cells. They also play a critical role maintaining the structure and permeability of endothelial cells. Tight junctions may also serve as leaky pathways by forming selective channels for small cations, anions, or water. The corresponding junctions that occur in invertebrates are septate junctions. Structure Tight junctions are composed of a branching network of sealing strands, each strand acting independently from the others. Therefore, the efficiency of the junction in preventing ion passage increases exponentially with the number of strands. Each strand is formed from a row of transmembrane proteins embedded in both plasma membranes, with extracellular domains joining one another directly. There are at least 40 different protei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD133
CD133 antigen, also known as prominin-1, is a glycoprotein that in humans is encoded by the ''PROM1'' gene. It is a member of pentaspan transmembrane glycoproteins, which specifically localize to cellular protrusions. When embedded in the cell membrane, the membrane topology of prominin-1 is such that the N-terminus extends into the extracellular space and the C-terminus resides in the intracellular compartment. The protein consists of five transmembrane segments, with the first and second segments and the third and fourth segments connected by intracellular loops while the second and third as well as fourth and fifth transmembrane segments are connected by extracellular loops. While the precise function of CD133 remains unknown, it has been proposed that it acts as an organizer of cell membrane topology. Tissue distribution CD133 is expressed in hematopoietic stem cells, endothelial progenitor cells, glioblastoma, neuronal and glial stem cells, various pediatric brain tu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells. Physiologically, brains exert centralized control over a body's other organs. They act on the rest of the body both by generating patterns of muscle activity and by driving the secretion of chemicals called hormones. This centralized control allows rapid and coordinated responses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
