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Ectoderm
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 cre ... [...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 respectively th ... [...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 septum of ... [...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 * Cortic ... References Ex ... [...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] |
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] |
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 neural crest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryonic Development
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 ner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endoderm
Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm. The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of multiple systems. In plant biology, endoderm corresponds to the innermost part of the cortex ( bark) in young shoots and young roots often consisting of a single cell layer. As the plant becomes older, more endoderm will lignify. Production The following chart shows the tissues produced by the endoderm. The embryonic endoderm develops into the interior linings of two tubes in the body, the digestive and respiratory tube. Liver and pancreas cells are believed to derive from a common precursor. In humans, the endoderm can differentiate into distinguishable organs after 5 wee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karl Ernst Von Baer
Karl Ernst Ritter von Baer Edler von Huthorn ( – ) was a Baltic German scientist and explorer. Baer was a naturalist, biologist, geologist, meteorologist, geographer, and is considered a, or the, founding father of embryology. He was a member of the Russian Academy of Sciences, a co-founder of the Russian Geographical Society, and the first president of the Russian Entomological Society, making him one of the most distinguished Baltic German scientists. Life Karl Ernst von Baer was born into the Baltic German noble Baer family ( et) in the Piep Manor ( et), Jerwen County, Governorate of Estonia (in present-day Lääne-Viru County, Estonia), as a knight by birthright. His patrilineal ancestors were of Westphalian origin and originated in Osnabrück. He spent his early childhood at Lasila manor, Estonia. He was educated at the Knight and Cathedral School in Reval (Tallinn) and the Imperial University of Dorpat (Tartu). In 1812, during his tenure at the univ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estonia
Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe, Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea, sea across from Sweden, to the south by Latvia, and to the east by Lake Peipus and Russia. The territory of Estonia consists of the mainland, the larger islands of Saaremaa and Hiiumaa, and over 2,200 other islands and islets on the eastern coast of the Baltic Sea, covering a total area of . The capital city Tallinn and Tartu are the two List of cities and towns in Estonia, largest urban urban area, areas of the country. The Estonian language is the indigenous language, autochthonous and the official language of Estonia; it is the first language of the majority of its Estonians, population, as well as the world's second most spoken Finnic languages, Finnic Uralic languages, language. The land of what is now modern Estonia has been inhabited by ''Early modern human, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prussia
Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was '' de facto'' dissolved by an emergency decree transferring powers of the Prussian government to German Chancellor Franz von Papen in 1932 and ''de jure'' by an Allied decree in 1947. For centuries, the House of Hohenzollern ruled Prussia, expanding its size with the Prussian Army. Prussia, with its capital at Königsberg and then, when it became the Kingdom of Prussia in 1701, Berlin, decisively shaped the history of Germany. In 1871, Prussian Minister-President Otto von Bismarck united most German principalities into the German Empire under his leadership, although this was considered to be a "Lesser Germany" because Austria and Switzerland were not included. In November 1918, the monarchies were abolished and the nobility lost its political power during the Ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blastula
Blastulation is the stage in early animal embryonic development that produces the blastula. In mammalian development the blastula develops into the blastocyst with a differentiated inner cell mass and an outer trophectoderm. The blastula (from Greek '' βλαστός'' ( meaning ''sprout'')) is a hollow sphere of cells known as blastomeres surrounding an inner fluid-filled cavity called the blastocoel. Embryonic development begins with a sperm fertilizing an egg cell to become a zygote, which undergoes many cleavages to develop into a ball of cells called a morula. Only when the blastocoel is formed does the early embryo become a blastula. The blastula precedes the formation of the gastrula in which the germ layers of the embryo form. A common feature of a vertebrate blastula is that it consists of a layer of blastomeres, known as the blastoderm, which surrounds the blastocoel. In mammals, the blastocyst contains an embryoblast (or inner cell mass) that will eventually give r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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