Morphogenesis (from the Greek morphê shape and genesis creation),( literally, "beginning of the shape"), is one of three fundamental aspects of developmental biology along with the control of cell growth and cellular differentiation. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Developmental Biology is the official journal of the Society for Developmental Biology. The term cell growth is used in two different ways in Biology. In Developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized Cell type. Morphogenesis is concerned with the shapes of tissues, organs and entire organisms and the positions of the various specialized cell types. Cell growth and differentiation can take place in cell culture or inside of tumor cell masses without the normal morphogenesis that is seen in an intact organism. The study of morphogenesis involves an attempt to understand the processes that control the organized spatial distribution of cells that arises during the embryonic development of an organism and that give rise to the characteristic forms of tissues, organs, and overall body anatomy. Developmental Biology is the official journal of the Society for Developmental Biology. Tissue is a cellular organizational level intermediate between cells and a complete organism In Biology, an organ ( Latin: organum, "instrument tool" from Greek όργανον - organon "organ instrument Anatomy (from the Greek anatomia, from ana separate apart from and temnein, to cut up cut open is a branch of Biology that is the consideration In the human embryo, the change from a cluster of nearly identical cells at the blastula stage to a post-gastrulation embryo with structured tissues and organs is controlled by the genetic "program" and can be modified by environmental factors. Stem cells are cells found in most if not all multi-cellular Organisms. The blastula is an early stage of Embryonic development in Animals It is also called blastosphere Gastrulation is a phase early in the development of animal Embryos during which the morphology of the embryo is dramatically restructured by Cell migration. Tissue is a cellular organizational level intermediate between cells and a complete organism In Biology, an organ ( Latin: organum, "instrument tool" from Greek όργανον - organon "organ instrument The term morphogenesis can also be used to describe the development of unicellular life forms that do not have an embryonic stage in their life cycle, or to refer to the evolution of a body structure within a taxonomic group. eVolution is the third Album by eLDee, it was due to be released in 2008 Taxonomy is the practice and science of classification The word comes from the Greek, taxis (meaning 'order' 'arrangement' and, nomos Morphogenetic responses may be induced in organisms by hormones, by environmental chemicals ranging from substances produced by other organisms to toxic chemicals or radionuclides released as pollutants, and other plants, or by mechanical stresses induced by spatial patterning of the cells. Hormones (from Greek ὁρμή - "impetus" are chemicals released by cells that affect cells in other parts of the body A toxin ( Greek:, toxikon, lit (poison for use on arrows is a Poisonous substance produced by living cells or organisms that is active at very low A radionuclide is an Atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created

History

Some of the earliest ideas on how physical and mathematical processes and constraints affect biological growth were written by D'Arcy Wentworth Thompson and Alan Turing. Sir D'Arcy Wentworth Thompson ( May 2, 1860, Edinburgh &ndash June 21, 1948 St Alan Mathison Turing, OBE, FRS (ˈt(jʊ(ərɪŋ (23 June 1912 &ndash 7 June 1954 was an English Mathematician These works postulated the presence of chemical signals and physico-chemical processes such as diffusion, activation, and deactivation in cellular and organismic growth. The fuller understanding of the mechanisms involved in actual organisms required the discovery of DNA and the development of molecular biology and biochemistry. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known Molecular biology is the study of Biology at a molecular level Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as

Molecular basis

Several types of molecules are particularly important during morphogenesis. Morphogens are soluble molecules that can diffuse and carry signals that control cell differentiation decisions in a concentration-dependent fashion. A morphogen is a substance governing the pattern of tissue development and in particular the positions of the various specialized cell types within a tissue Morphogens typically act through binding to specific protein receptors. In Biochemistry, a receptor is a Protein molecule embedded in either the Plasma membrane or Cytoplasm of a cell to which a mobile signaling An important class of molecules involved in morphogenesis are transcription factor proteins that determine the fate of cells by interacting with DNA. In the field of Molecular biology, a transcription factor (sometimes called a sequence-specific DNA binding factor is a Protein that binds to specific sequences Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known These can be coded for by master regulatory genes and either activate or deactivate the transcription of other genes; in turn, these secondary gene products can regulate the expression of still other genes in a regulatory cascade. History See also History of genetics The existence of genes was first suggested by Gregor Mendel (1822-1884 who in the 1860s studied inheritance Transcription is the synthesis of RNA under the direction of DNA Another class of molecules involved in morphogenesis are molecules that control cell adhesion. Cellular adhesion is the binding of a cell to another cell or to a Surface or matrix. For example, during gastrulation, clumps of stem cells switch off their cell-to-cell adhesion, become migratory, and take up new positions within an embryo where they again activate specific cell adhesion proteins and form new tissues and organs. Gastrulation is a phase early in the development of animal Embryos during which the morphology of the embryo is dramatically restructured by Cell migration. Stem cells are cells found in most if not all multi-cellular Organisms. Several examples that illustrate the roles of morphogens, transcription factors and cell adhesion molecules in morphogenesis are discussed below. In the field of Molecular biology, a transcription factor (sometimes called a sequence-specific DNA binding factor is a Protein that binds to specific sequences

Cellular basis

Example of cell sorting out with cultured P19 embryonal carcinoma cells. The Embryonal Carcinoma is one of the several types of testicular (or ovarian) Germ cell tumors, which also include the Seminoma ( Dysgerminoma Live cells were stained with either DiI (red) or DiO (green). The Dii (also Dioi) were an independent Thracian tribe Swordsmen, who lived among the foothills of Mount Rhodope in Thrace The red cells were genetically altered and express higher levels of E-cadherin than the green cells. Genetic engineering, Recombinant DNA technology, genetic modification/manipulation (GM and gene splicing are terms that apply to the direct Cadherin 1 type 1 E-cadherin (epithelial, also known as CDH1, is a human Gene. After labeling, the two populations of cells were mixed and cultured together allowing the cells to form large multi-cellular mixed aggregates. Individual cells are less than 10 microns in diameter. A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre The image was captured by scanning confocal microscopy. Confocal laser scanning microscopy ( CLSM or LSCM) is a technique for obtaining high- resolution optical images

Morphogenesis arises because of changes in the cellular structure or how cells interact in tissues^[1]. Certain cell types "sort out". Cell "sorting out" means that when the cells physically interact they move so as to sort into clusters that maximize contact between cells of the same type. The ability of cells to do this comes from differential cell adhesion. Two well-studied types of cells that sort out are epithelial cells and mesenchymal cells. In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body Mesenchyme refers to loosely organized connective tissue present in the embryo regardless of origin During embryonic development there are some cellular differentiation events during which mesenchymal cells become epithelial cells and at other times epithelial cells differentiate into mesenchymal cells (see Epithelial-mesenchymal transition). In Developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized Cell type. Epithelial-mesenchymal transition (EMT is a program of development of biological cells characterized by loss of cell adhesion repression of E-cadherin expression Following epithelial-mesenchymal transition, cells can migrate away from an epithelium and then associate with other similar cells in a new location.

Adhesion

During embryonic development, cells sort out in different layers due to differential adhesion. Cells that share the same cell-to-cell adhesion molecules separate from cells that have different adhesion molecules. Cells sort based upon differences in adhesion between the cells, so even two populations of cells with different levels of the same adhesion molecule can sort out. In cell culture cells that have the strongest adhesion move to the center of a mixed aggregates of cells. Cell culture is the process by which prokaryotic, or eukaryotic cells are grown under controlled conditions

The molecules responsible for adhesion are called cell adhesion molecules (CAMs). Several types of cell adhesion molecules are known and one major class of these molecules are cadherins. Cadherins are a class of type-1 Transmembrane proteins They play important roles in Cell adhesion, ensuring that cells within tissues are bound together There are dozens of different cadherins that are expressed on different cell types. Cadherins bind to other cadherins in a like-to-like manner: E-cadherin (found on many epithelial cells) binds preferentially to other E-cadherin molecules. Mesenchymal cells usually express other cadherin types such as N-cadherin.

Extracellular Matrix

The extracellular matrix (ECM) is involved with separating tissues, providing structural support or providing a structure for cells to migrate on. In Biology, the extracellular matrix ( ECM) is the Extracellular part of animal tissue that usually provides structural support to the cells Collagen, laminin, and fibronectin are major ECM molecules that are secreted and assembled into sheets, fibers, and gels. Collagen is the main Protein of Connective tissue in Animals and the most abundant protein in Mammals making up about 50% of the whole-body protein Laminin is the major non-collagenous component of the Basal lamina, such as those on which cells of an Epithelium sit Fibronectin is a high-molecular-weight extracellular matrix Glycoprotein containing about 5% Carbohydrate that binds to membrane spanning Receptor proteins Multisubunit transmembrane receptors called integrins are used to bind to the ECM. Integrins are Cell surface receptors that interact with the Extracellular matrix (ECM and mediate various intracellular signals. Integrins bind extracellularly to fibronectin, laminin, or other ECM components, and intracellularly to microfilament-binding proteins α-actinin and talin to link the cytoskeleton with the outside. Microfilaments (or actin filaments) are the thinnest filaments of the Cytoskeleton found in the cytoplasm of all Eukaryotic cells. Actinin alpha 1, also known as ACTN1, is a human Gene. Talin ( Armenian: Թալին is a city in the Aragatsotn province of Armenia. cytoskeleton (also CSK is a cellular " Scaffolding " or " Skeleton " contained within the Cytoplasm. Integrins also serve as receptors to trigger signal transduction cascades when binding to the ECM. In Biology, signal transduction refers to any process by which a cell converts one kind of signal or stimulus into another A well-studied examples of morphogenesis that involve ECM is mammary gland ductal branching^[2],^[3]. Mammary glands are the organs that in Mammals produce Milk for the sustenance of the young

See also

• Pattern formation
• Reaction-diffusion
• Neurulation
• Gastrulation
• Axon guidance
• Eye development
• Polycystic kidney disease 2
• Drosophila embryogenesis
• Manuel DeLanda

References

1. ^ Morphogenesis and Cell Adhesion, in Developmental Biology, 6th Edition by Scott F. The science of pattern formation deals with the visible ( statistically) orderly outcomes of Self-organisation and the common principles behind similar Reaction–diffusion systems are mathematical models that describe how the concentration of one or more substances distributed in space changes under the influence of two processes local Neurulation is a part of Organogenesis in Vertebrate Embryos Steps of neurulation include the formation of the Dorsal nerve cord, and the eventual Gastrulation is a phase early in the development of animal Embryos during which the morphology of the embryo is dramatically restructured by Cell migration. Axon guidance (also called axon pathfinding) is a subfield of Neural development concerning the process by which Neurons send out Axons to reach The Eye develops from the Neural tube, the epidermis, and the periocular mesenchyme which receives contributions from both the Neural crest and Mesoderm Polycystic kidney disease 2 (autosomal dominant, also known as PKD2, is a human Gene. Drosophila has long been a favorite model system for geneticists and developmental biologists studying Embryogenesis. Manuel DeLanda, (born 1952 in Mexico City) is a Writer, Artist and Philosopher who has lived in New York since 1975 Gilbert (2000) Published by Sinauer Associates, Inc. ISBN 0-87893-243-7.
2. ^ Regulation of mammary gland branching morphogenesis by the extracellular matrix and its remodeling enzymes by Jimmie E. Fata, Zena Werb and Mina J Bissell in Breast Cancer Research (2004) 6(1): 1–11.
3. ^ Key stages in mammary gland development: The cues that regulate ductal branching morphogenesis by Mark D Sternlicht in Breast Cancer Research (2006) 8(1): 201.