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Ectodermal
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from the outer layer of germ cells. The word ectoderm comes from the Greek ''ektos'' meaning "outside", and ''derma'' meaning "skin".Gilbert, Scott F. Developmental Biology. 9th ed. Sunderland, MA: Sinauer Associates, 2010: 333-370. Print. Generally speaking, the ectoderm differentiates to form epithelial and neural tissues (spinal cord, peripheral nerves and brain). This includes the skin, linings of the mouth, anus, nostrils, sweat glands, hair and nails, and tooth enamel. Other types of epithelium are derived from the endoderm. In vertebrate embryos, the ectoderm can be divided into two parts: the dorsal surface ectoderm also known as the external ectoderm, and the neural plate, which invaginates to form the neural tube and neural crest. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neural Plate
The neural plate is a key developmental structure that serves as the basis for the nervous system. Cranial to the primitive node of the embryonic primitive streak, ectodermal tissue thickens and flattens to become the neural plate. The region anterior to the primitive node can be generally referred to as the neural plate. Cells take on a columnar appearance in the process as they continue to lengthen and narrow. The ends of the neural plate, known as the neural folds, push the ends of the plate up and together, folding into the neural tube, a structure critical to brain and spinal cord development. This process as a whole is termed primary neurulation. Signaling proteins are also important in neural plate development, and aid in differentiating the tissue destined to become the neural plate. Examples of such proteins include bone morphogenetic proteins and cadherins. Expression of these proteins is essential to neural plate folding and subsequent neural tube formation. Invol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germ Layer
A germ layer is a primary layer of cells that forms during embryonic development. The three germ layers in vertebrates are particularly pronounced; however, all eumetazoans (animals that are sister taxa to the sponges) produce two or three primary germ layers. Some animals, like cnidarians, produce two germ layers (the ectoderm and endoderm) making them diploblastic. Other animals such as bilaterians produce a third layer (the mesoderm) between these two layers, making them triploblastic. Germ layers eventually give rise to all of an animal’s tissues and organs through the process of organogenesis. History Caspar Friedrich Wolff observed organization of the early embryo in leaf-like layers. In 1817, Heinz Christian Pander discovered three primordial germ layers while studying chick embryos. Between 1850 and 1855, Robert Remak had further refined the germ cell layer (''Keimblatt'') concept, stating that the external, internal and middle layers form respectivel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nervous System
In Biology, biology, the nervous system is the Complex system, highly complex part of an animal that coordinates its Behavior, actions and Sense, sensory information by transmitting action potential, signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue first arose in Ediacara biota, wormlike organisms about 550 to 600 million years ago. In vertebrates it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor nerves or ''Efferent nerve fiber, efferent'' nerves, while those nerves that transmit information from the body to the CNS a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neural Crest
Neural crest cells are a temporary group of cells unique to vertebrates that arise from the embryonic ectoderm germ layer, and in turn give rise to a diverse cell lineage—including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia. After gastrulation, neural crest cells are specified at the border of the neural plate and the non-neural ectoderm. During neurulation, the borders of the neural plate, also known as the neural folds, converge at the dorsal midline to form the neural tube. Subsequently, neural crest cells from the roof plate of the neural tube undergo an epithelial to mesenchymal transition, delaminating from the neuroepithelium and migrating through the periphery where they differentiate into varied cell types. The emergence of neural crest was important in vertebrate evolution because many of its structural derivatives are defining features of the vertebrate clade. Underlying the development of neura ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Ectoderm
The surface ectoderm (or external ectoderm) forms the following structures: *Skin (only epidermis; dermis is derived from mesoderm) (along with glands, hair, and nails) * Epithelium of the mouth and nasal cavity and glands of the mouth and nasal cavity *Tooth enamel (as a side note, dentin and dental pulp are formed from ectomesenchyme which is derived from ectoderm (specifically neural crest cells and travels with mesenchmyal cells) *Epithelium of anterior pituitary *Lens, cornea, lacrimal gland, tarsal glands and the conjunctiva of the eye *Apical ectodermal ridge inducing development of the limb buds of the embryo. *Sensory receptors in epidermis See also *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 * Corticot ... References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuroectoderm
Neuroectoderm (or neural ectoderm or neural tube epithelium) consists of cells derived from ectoderm. Formation of the neuroectoderm is first step in the development of the nervous system. The neuroectoderm receives bone morphogenetic protein-inhibiting signals from proteins such as noggin, which leads to the development of the nervous system from this tissue. Histologically, these cells are classified as pseudostratified columnar cells. After recruitment from the ectoderm, the neuroectoderm undergoes three stages of development: transformation into the neural plate, transformation into the neural groove (with associated neural folds), and transformation into the neural tube. After formation of the tube, the brain forms into three sections; the hindbrain, the midbrain, and the forebrain. The types of neuroectoderm include: *Neural crest ** pigment cells in the skin ** ganglia of the autonomic nervous system ** dorsal root ganglia. **facial cartilage **aorticopulmonary s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biologist
A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual cell, a multicellular organism, or a community of interacting populations. They usually specialize in a particular branch (e.g., molecular biology, zoology, and evolutionary biology) of biology and have a specific research focus (e.g., studying malaria or cancer). Biologists who are involved in basic research have the aim of advancing knowledge about the natural world. They conduct their research using the scientific method, which is an empirical method for testing hypotheses. Their discoveries may have applications for some specific purpose such as in biotechnology, which has the goal of developing medically useful products for humans. In modern times, most biologists have one or more academic degrees such as a bachelor's degree plus an advanced degree like a master's degree or a doctorate. Like other scientists, biologi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinz Christian Pander
Heinz Christian Pander, also Christian Heinrich Pander ( – ), was a Russian Empire ethnic Baltic German biologist and embryologist. Biography In 1817 he received his doctorate from the University of Würzburg, and spent several years (1827–1842), performing scientific research from his estate in Carnikava (german: Zarnikau) on the banks of the Gauja River near Riga. In 1820 he took part in a scientific expedition to Bokhara as a naturalist. In 1826 he became a member of the Saint Petersburg Academy of Sciences. Research Pander studied the chick embryo and discovered the germ layers (i.e., three distinct regions of the embryo that give rise to the specific organ system). Because of these findings, he is considered by many to be the "founder of embryology". His work in embryology was continued by Karl Ernst von Baer (1792-1876), who expanded Pander's concept of germ layers to include all vertebrates. Pander performed important studies in the field of paleontology, bein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baltic Germans
Baltic Germans (german: Deutsch-Balten or , later ) were Germans, ethnic German inhabitants of the eastern shores of the Baltic Sea, in what today are Estonia and Latvia. Since their coerced resettlement in 1939, Baltic Germans have markedly declined as a geographically determined ethnic groups in Europe, ethnic group. However, it is estimated that several thousand people with some form of (Baltic) German ethnic identity, identity still reside in Latvia and Estonia. Since the Middle Ages, native German-speakers formed the majority of merchants and clergy, and the large majority of the Baltic nobility, local landowning nobility who effectively constituted a ruling class over indigenous Latvians, Latvian and Estonians, Estonian non-nobles. By the time a distinct Baltic German ethnic identity began emerging in the 19th century, the majority of self-identifying Baltic Germans were non-nobles belonging mostly to the urban and professional middle class. In the 12th and 13th centuri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vespertilio Murinus
The parti-coloured bat or rearmouse (''Vespertilio murinus'') is a species of vesper bat that lives in temperate Eurasia, from Western and Southern Europe, eastwards over the Caucasus and Iran into Mongolia, north-east China, Korea, Afghanistan and northern Pakistan. Description Their twittering call, similar to a bird's call, can be heard particularly in the autumn during the mating season. The parti-coloured bat has a body size of with a wingspan of , and a weight of . Its name is derived from its fur, which has two colours. Its back (dorsal side) is red to dark-brown, with silver-white-frosted hair. The ventral side is white or grey. The ears, wings and face are black or dark brown. The wings are narrow. The ears are short, broad and roundish. It is known to live up to 12 years. Behaviour These bats hunt for their prey, for example mosquitoes, caddis flies and moths, with a wide range of ultrasonic sounds, but especially around 25–27 kHz. They hunt after twilight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryogenesis
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres. The blastomeres are arranged as a solid ball that when reaching a certain size, called a morula, takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining of the womb. Once implanted the embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis. Gastrulation is the formation of the three germ layers that will form all of the different parts of the body. Neurulation forms the ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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