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Blaschko's Lines
Blaschko's lines, also called the lines of Blaschko, are lines of normal cell development in the skin. These lines are only visible in those with a mosaic skin condition or in chimeras where different cell lines contain different genes. These lines may express different amounts of melanin, or become visible due to a differing susceptibility to disease. In such individuals, they can become apparent as whorls, patches, streaks or lines in a linear or segmental distribution over the skin. They follow a ''V'' shape over the back, ''S''-shaped whirls over the chest and sides, and wavy shapes on the head. Not all mosaic skin conditions follow Blascko's lines. The lines are believed to trace the migration of embryonic cells. They do not correspond to nervous, muscular, or lymphatic systems. The lines are not unique to humans and can be observed in other non-human animals with mosaicism. Alfred Blaschko is credited with the first demonstration of these lines in 1901. Signs and sym ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incontinentia Pigmenti
Incontinentia pigmenti (IP) is a rare X-linked dominant genetic disorder that affects the skin, hair, teeth, nails and central nervous system. It is named from its appearance under a microscope. The disease is characterized by skin abnormalities that begin in childhood, usually a blistering rash which heals, followed by the development of harder skin growths. The skin may develop grey or brown patches which fade with time. Other symptoms can include hair loss, dental abnormalities, eye abnormalities that can lead to vision loss and lined or pitted fingernails and toenails. Associated problems can include delayed development, intellectual disability, seizures and other neurological problems. Most males with the disease do not survive to childbirth. Incontinentia pigmenti is caused by a mutation in the ''IKBKG'' gene, which encodes the NEMO protein, which serves to protect cells against TNF-alpha-induced apoptosis. A lack of IKBKG therefore makes cells more prone to apoptosis. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sex Linkage
Sex linked describes the sex-specific patterns of inheritance and presentation when a gene mutation (allele) is present on a sex chromosome (allosome) rather than a non-sex chromosome (autosome). In humans, these are termed X-linked recessive, X-linked dominant and Y-linked. The inheritance and presentation of all three differ depending on the sex of both the parent and the child. This makes them characteristically different from autosomal dominance and recessiveness. There are many more X-linked conditions than Y-linked conditions, since humans have several times as many genes on the X chromosome than the Y chromosome. Only females are able to be carriers for X-linked conditions; males will always be affected by any X-linked condition, since they have no second X chromosome with a healthy copy of the gene. As such, X-linked recessive conditions affect males much more commonly than females. In X-linked recessive inheritance, a son born to a carrier mother and an unaffected fath ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Cutaneous Conditions
Many skin conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square metres, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin.Burns, Tony; ''et al''. (2006) ''Rook's Textbook of Dermatology CD-ROM''. Wiley-Blackwell. . Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kraissl's Lines
Kraissl's lines are a set of anatomical skin lines. They differ from Langer's lines in that unlike Langer's lines, which are defined in term of collagen orientation, Kraissl's lines are the lines of maximum skin tension. Whereas Langer's lines were defined in cadavers, Kraissl's lines have been defined in living individuals. Also, the method used to identify Kraissl's lines is not traumatic. See also * Blaschko's lines * Langer's lines Langer's lines, Langer lines of skin tension, or sometimes called cleavage lines, are topological lines drawn on a map of the human body. They are parallel to the natural orientation of collagen fibers in the dermis, and generally perpendicular to ... References Skin lines {{Dermatology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermatome (anatomy)
A dermatome is an area of skin that is mainly supplied by afferent nerve fibres from the dorsal root of any given spinal nerve. There are 8 cervical nerves (C1 being an exception with no dermatome), 12 thoracic nerves, 5 lumbar nerves and 5 sacral nerves. Each of these nerves relays sensation (including pain) from a particular region of skin to the brain. The term is also used to refer to a part of an embryonic somite. Along the thorax and abdomen the dermatomes are like a stack of discs forming a human, each supplied by a different spinal nerve. Along the arms and the legs, the pattern is different: the dermatomes run longitudinally along the limbs. Although the general pattern is similar in all people, the precise areas of innervation are as unique to an individual as fingerprints. An area of skin innervated by a single nerve is called a peripheral nerve field. The word ''dermatome'' is formed from Ancient Greek δέρμα 'skin, hide' and τέμνω 'cut'. Clinical signif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-inactivation
X-inactivation (also called Lyonization, after English geneticist Mary Lyon) is a process by which one of the copies of the X chromosome is inactivated in therian female mammals. The inactive X chromosome is silenced by being packaged into a transcriptionally inactive structure called heterochromatin. As nearly all female mammals have two X chromosomes, X-inactivation prevents them from having twice as many X chromosome gene products as males, who only possess a single copy of the X chromosome (see dosage compensation). The choice of which X chromosome will be inactivated in a particular embryonic cell is random in placental mammals such as humans, but once an X chromosome is inactivated it will remain inactive throughout the lifetime of the cell and its descendants in the organism (its cell line). The result is that the choice of inactivated X chromosome in all the cells of the organism is a random distribution, often with about half the cells having the paternal X chromos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Langer's Lines
Langer's lines, Langer lines of skin tension, or sometimes called cleavage lines, are topological lines drawn on a map of the human body. They are parallel to the natural orientation of collagen fibers in the dermis, and generally perpendicular to the underlying muscle fibers. Langer's lines have relevance to forensic science and the development of surgical techniques. History The lines were first discovered in 1861 by Austrian anatomist Karl Langer (1819–1887), though he cited the surgeon Baron Dupuytren as being the first to recognise the phenomenon. Langer punctured numerous holes at short distances from each other into the skin of a cadaver with a tool that had a circular-shaped tip, similar to an ice pick. He noticed that the resultant punctures in the skin had ellipsoidal shapes. From this testing he observed patterns and was able to determine "line directions" by the longer axes of the ellipsoidal holes and lines. Application Knowing the direction of Langer's lines withi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Heredity
The ''Journal of Heredity'' is a peer-reviewed scientific journal concerned with heredity in a biological sense, covering all aspects of genetics. It is published by Oxford University Press on behalf of the American Genetic Association. History The trends in topics that have been published in the journal reflect the history of the discipline of genetics.Crow, J F (2004). "Genetics: Alive and Well. The First Hundred Years as Viewed Through the Pages of the Journal of Heredity. WILHEMINE E. KEY 2003 INVITATIONAL LECTURE". J Hered (95(5):365–374. Early issues included many papers on eugenics, particularly under the editorial leadership of the journal's first two editors-in-chief, Paul Popenoe and R. C. Cook. Emphasis on eugenics in the journal declined throughout the 1940s and 1950s as support for the topic waned in the scientific community and the general public; when Cook's daughter, Barbara Kuhn, took over as editor in 1962 after her father's 40-year service, "...the subject ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nevus
Nevus (plural nevi) is a nonspecific medical term for a visible, circumscribed, chronic lesion of the skin or mucosa. The term originates from ''nævus'', which is Latin for "birthmark"; however, a nevus can be either congenital (present at birth) or acquired. Common terms, including mole, birthmark, and beauty mark, are used to describe nevi, but these terms do not distinguish specific types of nevi from one another. Classification The term ''nevus'' is applied to a number of conditions caused by neoplasias and hyperplasias of melanocytes, as well as a number of pigmentation disorders, both hypermelanotic (containing increased melanin, the pigment responsible for skin color) and hypomelanotic (containing decreased melanin). Suspicious skin moles which are multi-colored or pink may be a finding in skin cancer. Increased melanin Usually acquired * Melanocytic nevus ** Melanocytic nevi can be categorized based on the location of melanocytic cells *** Junctional: epidermis * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lupus Erythematosus
Lupus erythematosus is a collection of autoimmune diseases in which the human immune system becomes hyperactive and attacks healthy tissues. Symptoms of these diseases can affect many different body systems, including joints, skin, kidneys, blood cells, heart, and lungs. The most common and most severe form is systemic lupus erythematosus. Signs and symptoms Symptoms vary from person to person, and may come and go. Almost everyone with lupus has joint pain and swelling. Some develop arthritis. Frequently affected joints are the fingers, hands, wrists, and knees. Other common symptoms include: * chest pain during respiration * joint pain (stiffness and swelling) * painless oral ulcer * fatigue * weight loss * headaches * fever with no other cause * Skin lesions that appear worse after sun exposure * general discomfort, uneasiness, or ill feeling ( malaise) * hair loss * sensitivity to sunlight * a "butterfly" facial rash, seen in about half of people with SLE * swollen lymp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichen Planus
Lichen planus (LP) is a chronic inflammatory and immune-mediated disease that affects the skin, nails, hair, and mucous membranes. It is not an actual lichen, and is only named that because it looks like one. It is characterized by polygonal, flat-topped, violaceous papules and plaques with overlying, reticulated, fine white scale ( Wickham's striae), commonly affecting dorsal hands, flexural wrists and forearms, trunk, anterior lower legs and oral mucosa. The hue may be gray-brown in people with darker skin. Although there is a broad clinical range of LP manifestations, the skin and oral cavity remain as the major sites of involvement. The cause is unknown, but it is thought to be the result of an autoimmune process with an unknown initial trigger. There is no cure, but many different medications and procedures have been used in efforts to control the symptoms. The term lichenoid reaction (lichenoid eruption or lichenoid lesion) refers to a lesion of similar or identical histopa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
