Histogenesis 2051700 204437937 2008-04-09T12:39:25Z JAnDbot 1725149 robot Adding: [[cs:Histogeneze]] [[Image:Endoderm_Mesoderm_Ectoderm.png|thumb|500px|This [[depiction]] represents the [[endoderm]], [[mesoderm]], and [[ectoderm]] respectively.]] '''Histogenesis''' is the formation of different [[Biological tissue|tissues]] from undifferentiated [[cell (biology)|cells]].[http://www.encarta.msn.com/dictionary_/Histogenesis.html] These cells are constituents of three primary [[germ layer]]s, the [[endoderm]], [[mesoderm]], and [[ectoderm]]. The science of the microscopic structures of the tissues formed within histogenesis is termed [[histology]]. ==Germ layers== [[Image:Gastrulation.png|thumb|300px|'''[[Gastrulation]] of a [[diploblasty|diploblast]]:''' The formation of germ layers from a (1) [[blastula]] to a (2) [[gastrula]]. Some of the ectoderm cells (orange) move inward forming the endoderm (red).]] {{main|Germ layer}} A '''germ layer''' is a collection of [[cell (biology)|cell]]s, formed during animal and mammalian [[embryogenesis]]. Germ layers are typically pronounced within [[vertebrate]] organisms; however,[[animal]]s or mammals more complex than [[sea sponge|sponge]]s ([[eumetazoa]]ns and [[wikispecies:agnotozoa|agnotozoans]]) produce two or three primary tissue layers. Animals with [[symmetry (biology)#Radial symmetry|radial symmetry]], such as [[cnidaria]]ns, produce two layers, called the [[ectoderm]] and [[endoderm]]. Therefore, they are [[diploblastic]]. Animals with [[symmetry (biology)#Bilateral symmetry|bilateral symmetry]] produce a third layer in-between called [[mesoderm]], making them [[triploblastic]]. Germ layers will eventually give rise to all of an animal’s or mammal's [[biological tissue|tissues]] and [[organ (anatomy)|organ]]s through a process called [[organogenesis]]. ===Endoderm=== {{main|Endoderm}} The '''endoderm''' is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the [[archenteron]] form the inner layer of the [[gastrula]], which develops into the [[endoderm]]. Initially, the endoderm consists of flattened cells, which subsequently become columnar. ===Mesoderm=== {{main|Mesoderm}} The '''mesoderm''' germ layer forms in the [[embryo]]s of [[animal]]s and [[mammal]]s more complex than [[cnidaria]]ns, making them [[triploblastic]]. During [[gastrulation]], some of the cells migrating inward to form the [[endoderm]] form an additional layer between the endoderm and the [[ectoderm]]. This key innovation evolved hundreds of millions of years ago and led to the evolution of nearly all large, complex animals. The formation of a mesoderm led to the formation of a [[body cavity|coelom]]. Organs formed inside a coelom can freely move, grow, and develop independently of the body wall while fluid cushions and protects them from shocks. ===Ectoderm=== {{main|Ectoderm}} The '''ectoderm''' is the start of a tissue that covers the body surfaces. It emerges first and forms from the outermost of the [[germ layer]]s. ==Production== [[Image:Germ_layers.png|thumb|575px|The [[endoderm]] produces tissue within the [[lung]]s, [[thyroid]], and [[pancreas]]. The [[mesoderm]] aids in the production of [[cardiac muscle]], [[skeletal muscle]], [[smooth muscle]], tissues within the [[kidney]]s, and [[red blood cell]]s. The [[ectoderm]] produces tissues within the [[Epidermis (skin)|epidermis]] and aids in the formation of [[neuron]]s within the brain, and [[melanocytes]].]] [[Image:cell differentiation.gif|right|thumb|300px|Organs derived from each germ layer. Image from [http://www.ncbi.nih.gov/About/primer/genetics_cell.html NCBI].]] The proceeding graph represents the products produced by the three germ layers. {| class="wikitable" ! Germ Layer !! Category !! Product |- | Endoderm || General<ref>The '''General''' category denotes that all or most of the [[animal]]s containing this layer produce the adjacent product.</ref> || [[Gastrointestinal tract]] |- | Endodern || General || [[Respiratory tract]] |- | Endoderm || General || [[Endocrine]] glands and organs ([[liver]] and [[pancreas]]) |- | Mesoderm || General || [[skeletal system|Bones]] |- | Mesoderm || General || Most of the [[Circulatory system]] |- | Mesoderm || General || [[Connective tissue]]s of the gut and [[integumentary system|integuments]] |- | Mesoderm || General || [[gastrointestinal tract#Lower gastrointestinal tract|Excretory Tract]] |- | Mesoderm || General || [[Mesenchyme]] |- | Mesoderm || General || [[Mesothelium]] |- | Mesoderm || General || [[Muscular system|Muscles]] |- | Mesoderm || Gemeral || [[Peritoneum]] |- | Mesoderm || General || [[Reproductive System]] |- | Mesoderm || General || [[Urinary System]] |- | Mesoderm || Vertebrate<ref>The '''Vertebrate''' category denotes that all or most of the [[vertebrate]]s containing this layer produce the adjacent product.</ref> || [[Chordamesoderm]] |- | Mesoderm || Vertebrate || [[Paraxial mesoderm]] |- | Mesoderm || Vertebrate || [[Intermediate mesoderm]] |- | Mesoderm || Vertebrate || [[Lateral plate mesoderm]] |- | Ectoderm || General || [[Nervous system]] |- | Ectoderm || General || Outer part of [[integumentary system|integument]] |- | Ectoderm || Vertebrate || [[Skin]] (along with [[glands]], [[hair]], [[nail (anatomy)|nails]]) |- | Ectoderm || Vertebrate || [[Epithelium]] of the [[mouth]] and [[nasal cavity]] |- | Ectoderm || Vertebrate || [[lens (vision)|Lens]] and [[cornea]] of the [[eye]] |- | Ectoderm || Vertebrate || [[Melanocytes]] |- | Ectoderm || Vertebrate || [[Peripheral nervous system]] |- | Ectoderm || Vertebrate || Facial [[cartilage]] |- | Ectoderm || Vertebrate || [[Dentin]] (in teeth) |- | Ectoderm || Vertebrate || [[Brain]] ([[rhombencephalon]], [[mesencephalon]] and [[prosencephalon]]) |- | Ectoderm || Vertebrate || [[Spinal cord]] and [[motor neuron]]s |- | Ectoderm || Vertebrate || [[Retina]] |- | Ectoderm || Vertebrate || [[Posterior pituitary]] |} ==See also== *[[Histology]] ==References== <div class="references-small"> <references /> * Microsoft Corporation. [http://www.encarta.msn.com/dictionary_/Histogenesis.html Histogenesis]. ''Encarta World English Dictionary (North American Edition)''. URL accessed on [[14 May]] [[2005]]. * Evers, Christine A., Lisa Starr. ''Biology:Concepts and Applications.'' 6th ed. United States:Thomson, 2006. ISBN 0-534-46224-3. </div> ==External links== {{wiktionary|histogenesis}} *{{en icon}} [http://www.uoguelph.ca/zoology/devobio/splab7/index.htm Derivatives of the Ectoderm] *{{en icon}} [http://www.uoguelph.ca/zoology/devobio/splab8/index.htm Derivatives of the Endoderm and Mesoderm] {{Embryology}} {{Germ layer}} [[Category:Developmental biology]] [[Category:Embryology]] [[Category:Histology]] [[cs:Histogeneze]] [[fr:Histogenèse]] [[pl:Histogeneza]] [[pt:Histogênese]] [[ru:Гистогенез]] [[sr:Хистогенеза]] [[uk:Гістогенез]]