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Developmental Signaling Center
A developmental signaling center is defined as a group of cells that release various morphogens which can determine the fates, or destined cell types, of adjacent cells. This process in turn determines what tissues the adjacent cells will form. Throughout the years, various development signaling centers have been discovered. Spemann-Mangold organizer In 1924, Hans Spemann and Hilde Mangold discovered a region in the dorsal blastopore lip of an amphibian embryo that induced certain neighboring cells into becoming neural tissue. This Spemann-Mangold organizer was the first time that a developmental organizer region was identified and studied.Spemann, Hans (2001). "Induction of embryonic primordia by implantation of organizers from a different species". International Journal of Developmental Biology. 45 (1): 13–38. Since then many analogous organizers have been found in other organisms. The Spemann-Mangold organizer is important to developmental biology because it was t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.Cell Movements and the Shaping of the Vertebrate Body in Chapter 21 of Molecular Biology of the Cell '' fourth edition, edited by Bruce Alberts (2002) published by Garland Science. The Alberts text discusses how the "cellular building blocks" move to shape developing s. It is also common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chordin
Chordin (from Greek χορδή, string, catgut) is a protein with a prominent role in dorsal–ventral patterning during early embryonic development. In humans it is encoded for by the ''CHRD'' gene. History Chordin was originally identified in the African clawed frog (''Xenopus laevis'') in the laboratory of Edward M. De Robertis as a key developmental protein that dorsalizes early vertebrate embryonic tissues. It was first hypothesized that chordin plays a role in the dorsal homeobox genes in Spemann's organizer. The chordin gene was discovered through its activation following use of gsc ( goosecoid) and Xnot mRNA injections. The discoverers of chordin concluded that it is expressed in embryo regions where gsc and Xnot were also expressed, which included the prechordal plate, the notochord, and the chordoneural hinge. The expression of the gene in these regions led to the name chordin. Initial functions of chordin were thought to include recruitment of neighboring cells ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Pole
In developmental biology, an embryo is divided into two hemispheres: the animal pole and the vegetal pole within a blastula. The animal pole consists of small cells that divide rapidly, in contrast with the vegetal pole below it. In some cases, the animal pole is thought to differentiate into the later embryo itself, forming the three primary germ layers and participating in gastrulation. The vegetal pole contains large yolky cells that divide very slowly, in contrast with the animal pole above it. In some cases, the vegetal pole is thought to differentiate into the extraembryonic membranes that protect and nourish the developing embryo, such as the placenta in mammals and the chorion in birds. In amphibians, the development of the animal-vegetal axis occurs prior to fertilization.Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. Early Amphibian Development. Available from: https://www.ncbi.nlm.nih.gov/books/NBK10113/ Sperm entry can occu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noggin (protein)
Noggin, also known as NOG, is a protein that is involved in the development of many body tissues, including nerve tissue, muscles, and bones. In humans, noggin is encoded by the ''NOG'' gene. The amino acid sequence of human noggin is highly homologous to that of rat, mouse, and '' Xenopus'' (an aquaticfrog genus). Noggin is an inhibitor of several bone morphogenetic proteins (BMPs): it inhibits at least BMP2, 4, 5, 6, 7, 13, and 14. The protein's name, which is a slang English-language word for "head", was coined in reference to its ability to produce embryos with large heads when exposed at high concentrations. Function Noggin is a signaling molecule that plays an important role in promoting somite patterning in the developing embryo. It is released from the notochord and regulates bone morphogenic protein 4 (BMP4) during development. The absence of BMP4 will cause the patterning of the neural tube and somites from the neural plate in the developing em ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chordin
Chordin (from Greek χορδή, string, catgut) is a protein with a prominent role in dorsal–ventral patterning during early embryonic development. In humans it is encoded for by the ''CHRD'' gene. History Chordin was originally identified in the African clawed frog (''Xenopus laevis'') in the laboratory of Edward M. De Robertis as a key developmental protein that dorsalizes early vertebrate embryonic tissues. It was first hypothesized that chordin plays a role in the dorsal homeobox genes in Spemann's organizer. The chordin gene was discovered through its activation following use of gsc ( goosecoid) and Xnot mRNA injections. The discoverers of chordin concluded that it is expressed in embryo regions where gsc and Xnot were also expressed, which included the prechordal plate, the notochord, and the chordoneural hinge. The expression of the gene in these regions led to the name chordin. Initial functions of chordin were thought to include recruitment of neighboring cells ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryo
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 nervou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homeobox
A homeobox is a DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. For instance, mutations in a homeobox may change large-scale anatomical features of the full-grown organism. Homeoboxes are found within genes that are involved in the regulation of patterns of anatomical development (morphogenesis) in animals, fungi, plants, and numerous single cell eukaryotes. Homeobox genes encode homeodomain protein products that are transcription factors sharing a characteristic protein fold structure that binds DNA to regulate expression of target genes. Homeodomain proteins regulate gene expression and cell differentiation during early embryonic development, thus mutations in homeobox genes can cause developmental disorders. Homeosis is a term coined by William Bateson to describe the outright replacement of a discrete body part with another body part, e.g. antennapedia—replacement of the antenna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Organs
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue and smooth muscle tissue. Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system. An organ's tissues can be broadly categorized as parenchyma, the functional tissue, and stroma, the structural tissue with supportive, connective, or ancillary functions. For example, the gland's tissue that makes the hormones is the parenchyma, whereas the stroma includes the nerves that innervate the parenchyma, the blood vessels that oxygenate and nourish it and carry away its metabolic wastes, and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asymmetry
Asymmetry is the absence of, or a violation of, symmetry (the property of an object being invariant to a transformation, such as reflection). Symmetry is an important property of both physical and abstract systems and it may be displayed in precise terms or in more aesthetic terms. The absence of or violation of symmetry that are either expected or desired can have important consequences for a system. In organisms Due to how cell (biology), cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with symmetry (biology), biological symmetry also being common in at least one dimension. Louis Pasteur proposed that biological molecules are asymmetric because the cosmic [i.e. physical] forces that preside over their formation are themselves asymmetric. While at his time, and even now, the symmetry of physical processes are highlighted, it is known that there are fundamental physical asymmetries, starting with time. Asymmetry in biology Asym ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart
The heart is a muscular organ found in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the chest, called the mediastinum. In humans, other mammals, and birds, the heart is divided into four chambers: upper left and right atria and lower left and right ventricles. Commonly, the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. Fish, in contrast, have two chambers, an atrium and a ventricle, while most reptiles have three chambers. In a healthy heart, blood flows one way through the heart due to heart valves, which prevent backflow. The heart is enclosed in a protective sac, the pericardium, which also contains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Head
A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may not have a head, but many bilaterally symmetric forms do, regardless of size. Heads develop in animals by an evolutionary trend known as cephalization. In bilaterally symmetrical animals, nervous tissue concentrate at the anterior region, forming structures responsible for information processing. Through biological evolution, sense organs and feeding structures also concentrate into the anterior region; these collectively form the head. Human head The human head is an anatomical unit that consists of the skull, hyoid bone and cervical vertebrae. The term "skull" collectively denotes the mandible (lower jaw bone) and the cranium (upper portion of the skull that houses the brain). Sculptures of human heads are generally based on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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