NAILS

From Big Medical Encyclopedia

NAILS [unguis (PNA); ungues (JNA, BNA)] — the appendages of skin in the form of dense horn plates which are located on a dorsum of trailer phalanxes of fingers of hands and legs.

N at the person protect soft tissues of finger-tips from various external influences, hl. obr. mechanical.

Embryology

At the person N. begin to develop on the 3rd month of an antenatal life. At first there are primary nail beds (a bed of a nail, T.), or fields, to-rye represent modified sites of skin on back (dorsal) surfaces trailer (distal, T.) phalanxes of fingers of hands and legs, consisting of reinforced epithelial layer and the subject connective tissue basis — dermas; further epithelial layer slightly plunges into connecting fabric of a derma; with side and back the parties it is surrounded by the skin folds making nail rollers (rollers of a nail, T.). At the same time in the center of nail beds there is a keratinization (keratinization of an epithelium) creating so-called false nails. Actually N. develop at later stage of development from the epithelium which is in back (proximal) parts of the nail beds covered with back nail rollers. This epithelium plays a role of a nail matrix (a matrix of a nail, T.), i.e. is the place of growth of a nail plate (plates of a nail, T.). In the beginning the developing nail plates are completely covered with the thin keratinized coat, to-ry passes to them from nail rollers. By the end of the pre-natal period this layer remains at edges of nail plates and remains on their rear edge during all subsequent life in the form of a so-called eponychium (eponychium) — a nadnogtevy plate (thin skin).

Owing to slow growth in the pre-natal period of N. reach the ends of fingers only by the time of the birth, remaining in the forefronts very thin and soft. After the birth there is a strengthened process of growth and N.'s keratinization: nail plates turn into dense horn educations.

Anatomy and histology

Fig. 1. Diagrammatic representation of a nail phalanx of a finger of a hand: 1 — skin of a finger; 2 - back nail roller; 3 — an eponychium; 4 — an alveole of a nail: 5 — a plate of a nail; 6 — edge of a nail; 7 — a cross groove of a nail bed; 8 — the lateral nail roller.

Nail plates of a convex squared shape with the rounded-off corners, white color with a pink shade. N.'s coloring depends on degree of a krovenapolneniye of vessels of a nail bed and transparency of a nail plate. An outer surface smooth, internal — uneven (longitudinal rollers alternate with grooves). The sizes of nail plates at adults: length is 10 — 15 mm, width is 10 — 17 mm, thickness is 0,30 — 0,37 mm. The nail plate (lamina unguis) lies on a nail bed (lectulus unguis), a cut from sides and at the basis is limited to folds of skin — nail rollers — lateral and back (vallum unguis lat., post.). Between a nail bed and nail rollers there are narrow lateral and back nail bosoms (sinus unguis lat., post.). The nail plate the edges presses in them, and is especially deep in a back nail bosom. The nail plate is subdivided into three parts: root, body and edge. A root H. (radix unguis) call the tail of a nail plate lying in a back nail bosom and covered from above with the nail roller. Only the small site of a root H. acts from under the back roller in the form of a white strip of a semi-lunar form — an alveole of II. (lunula). The alveole is better noticeable on N. of thumbs. Edge, or a ledge, N. (margo liber unguis) is the free front end of a nail plate supporting limits of a nail bed. In the course of N.'s growth its edge gradually increases therefore it is regularly cut, giving N. the desirable form and the sizes. Body of H. (corpus unguis) is made by other part of a nail plate limited in front to N.'s edge, behind a root H., and from sides lateral rollers (fig. 1).

The nail plate is formed by horn scales (squamulae corneae) of a flat polygonal form skintight to each other filled with a firm keratin (eukeratiny). In horn scales of a root H., except a keratin, there are remains of cellular kernels. The nail plate is translucent.

The nail bed includes an epithelium and the subject connecting fabric — a derma, or a corium. An epithelium of a nail bed — the Hyponychial plate (thin skin), or giionikhiya (hyponychium) — represents the rostkovy layer of epidermis of skin consisting of basal and acanthceous cells. The nail plate lying on it corresponds to a corneous layer of epidermis. Giionikhy presses in a derma of a nail bed in the form of longitudinal combs, to-rye sharply break under free edge of N. where giionikhiya comes to an end with the thickening delimited from skin of a finger by a nail groove. Connecting fabric between combs a giponpkhiya forms a number of the small longitudinal folds rich with blood vessels. Considerable part of collagenic fibers of a nail bed goes deep into to a trailer bone phalanx of a finger where they are interwoven into a periosteum and thanks to it carry out a role of a bridle of a nail (retinaculum unguis). The proximal (back) site epiteltsya a nail bed — a nail matrix (matrix unguis) — thicker, is located on connecting fabric of the derma forming not longitudinal folds, but high nipples, to-rye krovosnabzhatsya plentifully and innervated. The front border of a nail matrix is designated on N. by an alveole, white color a cut is caused by the fact that through a thick epithelium of a nail matrix blood vessels of a derma are not visible.

Between a matrix and a root H. there is no sharp border — the matrix is a rostkovy layer of an epithelium, and substance of a root H. — its corneous layer. The matrix consists of large light slabodifferentsirovanny epithelial cells — onychoblasts (onychoblasti). In their cytoplasm preke-ratinovy fibrilla collects and there are no granules of eleidin. In a matrix onychoblasts breed (share) and then are exposed to firm keratinization (see. Keratinization ), turning without intermediate stages into horn scales of a nail plate; at the same time the peeling, i.e. rejection of horn cells from a surface, does not occur. Therefore, continuously being replenished with cells in the matrix, the nail plate gradually grows in length. Growth of a nail plate happens also on other part of a nail bed, but much more slowly and hl. obr. in thickness. In one month it grows approximately by 1,5 — 3 mm, and its regeneration happens in 96 — 115 days. On N.'s hands grow by two-three times quicker, than standing; at men N.'s growth is more expressed, than at women. Cross grooves on a surface of a nail plate indicate change of rate of its growth that takes place at damages of a matrix of N.

Fig. 2. The diagrammatic representation of cross section of a phalanx of a finger in a zone of a nail: 1 — a plate of a nail; 2 — giponikhiya; 3 — a derma; 4 — a lateral bosom of a nail; 5 — the lateral nail roller; 6 — an eponychium; 7 — a bone phalanx.
Fig. 3. The diagrammatic representation of longitudinal section of a phalanx of a finger in a zone of a nail: 1 — a root of a nail; 2 — an eponychium; 3 — the back nail roller; 4 — a matrix of a nail; 5 — a derma; 6 — a bone phalanx.

Structure of nail rollers same, as well as skin (see). The Rostkovy layer of epidermis of nail rollers passes into an epithelium of a matrix and a nail bed, and a corneous layer — a part in substance of a nail plate, a part approaches it from edges, forming the eponychium (a nadnogtevy plate) well noticeable on a surface of an alveole of N.; it closes access to a root of a nail (fig. 2, 3).

N. contains 10,1 — 13,7% of water and 0,15 — 0,76% of zhiropodobny substances (cholesterol and its ethers). From organic matters the main are protein — the keratin steady against action of various chemical agents having property of double refraction and containing sulfur (to 5%), cystine (10 — 12,9%), arginine (7,1 — 10%), tyrosine (apprx. 3%), a lysine (2,6 — 2,8%), phenylalanine (2,5%), tryptophane (1,1%), a histidine (0,5%), and from mineral substances calcium, phosphorus, zinc, arsenic, etc.

N.'s blood supply is carried out by manual arteries, branches to-rykh form the fascial and skin textures passing into textures in a derma of nail beds and a matrix of N. The final arteries branching on capillaries pleated depart from them and nipples of a derma of N. Krov comes to veniplexes and then gathers in manual veins. An arteriovenous anastomosis of glomal type is widespread in vascular textures of N.

N are well innervated. In fabrics of nail beds and N.'s matrix numerous sensitive are located nerve terminations (see).

Pathology

Diseases of a nail plate and a nail bed (onychia), and also nail rollers — paronychias (see) can be inborn and acquired.

Uniform classification of diseases of N. does not exist. J. Heller in 1927 allocated: inborn diseases of N., hyponychial tumors, N.'s diseases as symptoms of skin diseases, N.'s changes at diseases of all organism, N.'s defeat at diseases of a nervous system, N.'s change at fractures of bones, N.'s defeats at intoxications and the prof. diseases. Pardo Kastello (V. Pardo Castello, 1960) in pathology And. allocated specific defeats of N., an onikhodistro-fiya, N.'s defeat at a dermatosis and system diseases, inborn damages of nails.

O. K. Shaposhnikov (1961) divided N.'s pathology into four groups: inborn changes of N.; the trophic changes of N. connected with disturbance of functions of various bodies and systems (in particular, a nervous system); N.'s diseases connected with influence of local factors — physical, chemical, biological; N.'s changes at various diseases of skin.

Fig. 1. Nails of hands at an onychogryphosis: nail plates are sharply deformed, thickened, their color is changed. Fig. 2. Nails at psoriasis: nail plates grow dull, become fragile, the free edge is thickened and otsloyen from a nail bed.

Inborn changes of nails meet seldom. They are shown by a thickening, a hypertrophy (pachyonychia), thinning and an atrophy (onychoatrophia) of a nail plate, replacement with its shapeless horn masses (an epidermal nail); at an anonychia (anonychia congenita) — completely there is no one, several or all N., and the nail bed is covered with a thin skin. N., normal on the structure, can be increased (macronychia) or is reduced (mikroni-hiya) in sizes that is observed quite often in parallel with change of the sizes of all finger (macro - or a microdactylia). The nail plate can have various form: convex, flat — a platonikhiya, platonychia (fig. 4, a); concave, with saucer-shaped deepening — spoon-shaped N., a koilonychia, koilonychia (fig. 4,6); with longitudinal and cross striation, kogteobrazny — an onychogryphosis, onycho-gryphosis (tsvetn. fig. 1). At an onychogryphosis the nail plate is thickened (hyperonychia), becomes extraordinary firm, dim, lurid or brown color, reaches in length of several centimeters, rises and bent aside, reminding a claw or a mutton horn (fig. 4?). The free edge of N. can rise and have the form of a keg or a tower — so-called tower N. (ungues in turricula).

Inborn dystrophy of a nail bed is characterized hyperkeratosis (see). The union and N.'s deformation are observed at syndactylias (see).

Inborn changes of N. (a hereditary onikhodistrofiya) can be manifestation of a number of hereditary diseases of skin: ichthyosis (see), keratodermias, a violent epidermolysis (see. Epidermolysis violent ), diseases to Darya (see. to Darya disease ), etc. At a kongenitalny polykeratosis of Yadasson — Lewandowski (see. Yadassona — Lewandowski a syndrome ), to the being rare genodermatosis (see), the combination of an inborn pachyonychia (pachyonychia congenita) to a widespread follicular or symmetric palmar and bottom hyperkeratosis, bulging, a hyperhidrosis, anomalies of development of hair, teeth and bones, opacification of a cornea, a leukoplakia of a mucous membrane of an oral cavity, and also mental disturbances is noted. At inborn diseases of N. vitamin therapy, including long reception of vitamin A (100 000 ME a day), drugs gelatin are shown.

Rice 4. Pathological changes of nails: and — a plantonikhiya (a flat plate of a nail); — a koilonychia (saucer-shaped deepening of a plate of a nail); in — kogteobrazny nails (to an onychogryphosis of — dystrophy of a nail in the form of grooves of Bo; d — department of free edge of a nail plate in the form of the semi-lunar line at an onikholiziya; e — the Hyponychial hematoma; — the grown nail with an ulceration of the nail roller; z — a hyponychial fibromatosis.

Trophic changes of nails. Among the acquired N.'s changes (the acquired dystrophic onychia) the important place is taken by the defeats caused by trophic frustration in the field of a nail matrix with disturbance temporarily of its function. At the same time almost all N. quickly are surprised; changes of nail plates on fingers are in one stage of development, the inflammatory phenomena in the field of nail rollers are absent. The struck nail plates lose usual gloss, become dim, yellowish-gray; on their surface there are cross strips (plicae horizontales) called by the arc-shaped grooves of Bo (fig. 4, d), and pointed deepenings. Are less often observed fragility of H. (fragilitas unguis), onikhoreksis (onychorrhexis) — splitting of H. in lengthwise direction, beginning usually with free edge of a nail plate (plicae longitudinales); lag (onychochisia), or department (onycholysis), H. from a nail bed, N. developing gradually from a first line (fig. 4, e) towards an alveole (in nek-ry cases this process is connected with development of a hyponychial hyperkeratosis); an ulceration (helconyxis) and N.'s thickening, emergence of tuberosity on them. Bystry separation from the subject fabrics of a nail plate which then (e.g., at an insignificant injury) disappears is called onikho-madezy (onychomadesis). N. meet thinning and saucer-shaped concavity of a nail plate, the free edge a cut becomes jagged — an onychogryphosis, and also wide convex nail plates with the free edge bent from top to bottom — the so-called nails of Hippocrates (sy. Hippocrates a nail) which are combined with a thickening of trailer phalanxes of fingers (see. Drum fingers ). Median dystrophy of N. — a medial longitudinal groove, or the channel passing from an alveole to free edge of N. of thumbs of hands (dystrophia unguium mediana canaliformis) is occasionally observed.

At incomplete keratinization of cells of a nail plate owing to disturbance of normal function of a matrix in its thickness single or multiple spots or strips of milky-white color, a different form and the size — a so-called leukonychia, s are formed. canities of H. (leukonychia, or leukopathia unguium, canities unguium). Distinguish a leukonychia limited, or dot (l. punctata), polosovidny (l. striata) and a total leukonychia in the form of a set of the white spots covering all N. (l. totalis), edges more often happens inborn (an inborn leukonychia). Option of a leukonychia is «the messovsky strip» — emergence of the strip of white color located distalny alveoles cross to N.'s longitudinal axis, edges with N.'s growth moves ahead. In nek-ry cases development of a leukonychia is promoted by an injury, napr, at manicure. Manifestation of trophic disturbances of N. is also the nervous onychalgia which is characterized by a painful hyperesthesia of any part of a nail.

Dystrophic onychias can be observed at many inf. diseases (belly and typhus, pneumonia, malaria, scarlet fever, measles, rubella, dysentery, etc.), hron, specific infections (tuberculosis, syphilis, leprosy), diseases of a nervous system (neuritis of various origin, myelosyringosis, poliomyelitis, multiple sclerosis, back to tabes, etc.). N.'s dystrophy is noted at a Raynaud's disease, a varicosity, elephantiasis, atherosclerosis, rheumatism, funkts, frustration and diseases of endocrine system (a diffusion toxic craw, a hypothyroidism, an acromegalia, Itsenko's syndrome — Cushing, a tetany), at nek-ry diseases of blood (e.g., a chlorosis), a nutritional dystrophy, intoxications (profvrednost, hron, alcoholism, etc.), after heavy operations and childbirth. Dystrophic changes of N. meet at some hypovitaminoses. At N.'s pellagra become opaque, grayish-yellow color, become covered by longitudinal grooves, more rare cross white strips. At deficit of vitamin A N.'s thickening in connection with development of a hyponychial hyperkeratosis is noted. At a scurvy the hemorrhages in the field of a nail bed leading sometimes to peeling of nail plates can be observed.

At neuritis, a leprosy, a sclerodactylia the nadnogtevy plate can expand and cover a part of a nail plate, in particular an alveole, forming a so-called alate pleva (pterygium unguis), edges sometimes happens inborn.

At trophic changes of N. the drugs improving peripheric circulation are recommended inside (vitamins A, With, groups B, iron preparations, calcium, phosphorus, gelatin); locally at N.'s hypertrophies hot trays with the subsequent use of keratolytic means in the form of varnishes and ointments are shown; at an onychogryphosis — stripping of the struck N. after a preliminary softening of its 50% of salicylic or 20% ureal a plaster-hm, Onycholysinum; at they-holizise — rubbing in in a nail bed of corticosteroid ointments; at dystrophic onychias and paronychias — massage and novocainic blockade.

Also treatment of the basic disease which caused defeat of N is carried out.

Decolourizations of nails. N become pale at anemia, vasomotor spasms, red at a polycythemia. At jaundice, a carotenemia yellow coloring of N. can appear, at an addisonovy disease, long reception of antibiotics of group of tetracyclines, drugs of arsenic — brown, at intake of drugs of a quinolinic row — bluish or flavovirent. N.'s hyperpegmentation in the form of strips can be a constant (e.g., at a nevus of a nail bed) and temporary (after impact of x-ray emission, in nek-ry cases owing to treatment by corticosteroid hormones).

Injury of nails is usually connected with influence of local factors. The constant mechanical irritation of N. often causes thinning (deleting, grinding) of nail plates (e.g., a professional onychia in workers of brick and weaver's production). Destruction of free edge of a nail plate can be observed at an addiction (especially at children) to bite N. — so-called onychophagies (onychophagia). Repeated strippings of a nail plate sometimes cause gradual development of a total leukonychia. Different traumatic damages and wounds of a matrix of N. (bruises, squeezing, excessive moving away of the back nail roller at manicure) lead to change of a form of a nail plate, emergence on it longitudinal grooves, cracks, to splitting on two halves with consecutive development between them the horn roller, or a comb. The bruise or infringement of trailer phalanxes of fingers causes hyponychial hematomas — regional or total (fig. 4, e). Hemorrhages are followed by the acute pain which is replaced by numbness owing to a prelum of nerve terminations the streamed blood. At total hematomas the nail plate usually throughout separates from a bed and in 5 — 6 months is replaced with new, normal N. At localization of a hematoma in the field of an alveole when the matrix is involved in process, again formed nail plate quite often is deformed.

Often growing of edge of a nail plate, usually lateral, in the nail roller adjoining to it (fig. 4, g) — the so-called grown N. meets (see. grown ). Various traumatic damages of N. are observed also at the persons suffering from various persuasive states, napr, a mania of parasitism, so-called onychotillomania, at a cut destruction or own N.' wrest is made for the purpose of «removal of worms from under them».

N.'s damages can be caused by influence of high or low temperature, and also nek-ry types of a radiant energy. At freezing injuries of the I degree on nail plates quite often there are one or several cross grooves. At freezing injuries and burns of the II degree with localization of bubbles on a dorsum of trailer phalanxes of fingers of N. can exfoliate partially or completely from a nail bed. At deeper thermal influences there is a sharp damage of a nail bed and matrix leading to N.'s deformations up to development of an onychogryphosis, sometimes N.'s growth stops. At perfigeration (see), especially fingers of feet, development of a nodnogtevy hyperkeratosis and change of a form of a nail plate is possible. At the persons which are exposed to long impact of ionizing radiation the radiation injuries of skin which are combined with dystrophic changes of a nail plate (thinning, striation, fragility, various deformations) can be observed.

N.'s changes from effect of chemical substances are connected more often about professional harm-nostyami. At the same time color of nail plates can change owing to implementation of various colorants, napr, compounds of chrome. Long impact on N. of chemical irritants (alkalis, acids, corrosive sublimate, formalin, etc.) is frequent in combination with mechanical influence leads to thinning of free edge of a nail plate, an inflammation (it is frequent with ulcerations) a nail bed, to partial separation of a nail plate from a nail bed.

Changes of nails at various skin diseases. At to eczema (see) the dot or diffusion loosening, opacification of a nail plate, emergence on it cross and longitudinal grooves is quite often observed, flaking, N.'s splitting on two horn plates adjoining to each other — onikhoshizis is more rare (onychoschisis).

At psoriasis (see) N. are surprised often, especially at common and exudative forms, and also at a psoriasis erythrosis and arthropathies. Sometimes N.'s changes precede development of skin process (the isolated N.'s psoriasis). They grow dull, turn yellow, become fragile, their free edge is thickened and exfoliates from a nail bed — onycholysis psoriatica (tsvetn. fig. 2). Often at psoriasis there are punctulate deepenings on N.'s surfaces reminding a thimble — the so-called naperstko-Vyya nails; development of hyponychial hemorrhages, psoriasis paronychias, an onychogryphosis, an onychomalacia (hapalonychia) is possible.

At a pruritic dermatosis — a skin itch (see. Itch skin ), neurodermatitis (see) — the surface of a nail plate from friction about skin at its combing becomes brilliant, as if polished, the free edge of N. grinds off. At herpes red flat (see), especially generalized it is also long proceeding, on N. the longitudinal fillets and combs alternating among themselves are quite often formed various depth. N.'s defeat is possible also at many others is long the current dermatosis (keratoza, a gemodermiya, a scleroderma). At the Norwegian to a mange (see) N. are thickened, loosened, turning into shapeless horn weight. Emergence on skin of trailer phalanxes of brushes of sinyushnokrasny spots with a melkoplastinchaty peeling along with pallor in coloring of nail plates is characteristic of a system lupus erythematosus (see. Lupus erythematosus ). Fungus diseases of N. most often are caused by filamentous fungi (see. Onychomycosis ); defeat of the nail roller and a nail plate yeast-like fungi is possible (see. Candidiasis ).

Treatment of onychias of this group is carried out depending on a basic disease. Pyococci and a pyocyanic stick cause a paronychia and an onychia. To implementation inf. the agent agnails — small anguishes of skin of nail rollers promote.

Tumors of a nail bed meet seldom. The hyponychial fibromatosis (fibromatosis subungualis) described in 1916 belongs to benign tumors. Half of landom (R. Polland). The disease is characterized by development painless, dense, light pink color of the tumorous educations (fig. 4, h) representing growth of connecting fabric of a nail bed; it is often combined with adenoma of sebaceous glands of Pringl (see. Adenoma of sebaceous glands ). Carry dermoid cysts to malformations (see. Dermoid ). Perhaps also development hyponychial glomal tumor (see) and keratoacanthomas (see). The Hyponychial melanoma described by J. Getchinson under the name «melanotichesky nogteeda» belongs to malignant tumors of a nail bed; the tumor develops more often from pigmental nevus (see); in the beginning it represents the blue-black spot translucent through a nail plate and then a nodular form the education burgeoning and destroying by N. On a nail bed planocellular cancer in the form of slowly growing painful dense small knot gradually raising N. seldom develops; at disintegration of a tumor there comes its ulceration and bleeding. Separate cases of hyponychial sarcoma and Bowen's disease are described (see. Bowen disease ) with defeat of a nail bed. At hyponychial exostoses together with N. the nail bed is involved in process.

Treatment of tumors operational; apply radiation therapy or combine operation with the subsequent radiation therapy, use also diathermocoagulation.

Hygiene and prevention of diseases of nails

N.'s Hygiene consists in washing of hands with soap and a brush, cleaning of hyponychial spaces with a nogtechistka. Care of N. shall be regular. In process of N.'s growth it is regularly necessary to cut that serves the hygienic and cosmetic purposes. At the same time strict observance of sanitary and hygienic rules is important, it is necessary to avoid injuries of skin of nail rollers. Places of accidental cuts process hydrogen peroxide, tincture of iodine, etc.

During the carrying out manicure and pedicure in hairdressing salon it is necessary to observe also specified requirements; all tools should be disinfected in alcohol or special disinfecting solutions. After manicure and a pedicure light massage of fingers with nutritious cream is useful. The patient having diseases of nails (or at suspicion on an onychomycosis), manicure and a pedicure in hairdressing salons do not make.

Regular washing of legs and elimination of perspiration is prevention against implementation in N. of parasitic fungi and development of onychomycoses. Timely treatment of the diseases which are followed by onychias and paronychias, elimination of harmful effects of various irritants (chemical, mechanical) is one of prophylactics of damage of nails.



Bibliography: Andriasyan G. K. Fungus diseases of nails, M., 1951; Arabian A. N. and Boole porter JI. A. Trophoneurotic onychias, in book: Vopr, the general patol., clinics and treatments of a dermatosis, under the editorship of S.E. Gorbovitsky, page 181, JI., 1958; Ariyevich A. M. and Sh e of c and r at - l and L. T. Patologiya of nails, Tbilisi, 1976, bibliogr.; Histology, under the editorship of V. G. Yeliseyev, page 420, M., 1972; 3 and - varzin A. A. Kurs of histology and microscopical anatomy, page 342, JI., 1939; To and l and N of t and e in with to and I am K. A. Morfologiya and physiology of skin of the person, page 143, Kiev, 1972; M about to r about at with about in M. S. Kliniko-morfologichesky picture of dystrophies of nails of not clear etiology, Vestn, dermas, and veins., No. 5, page 37, 1974; Petten B. M. Embryology of the person, the lane with English, page 236, M., 1959; Sh e to l and to about in N. D. Diseases of nails, M., 1975, bibliogr.; Alkie-w i with z J. u. P f i s t e r R. Atlas der Nagelkrankheiten, Stuttgart — N. Y., 1976; Handbuch der Haut-und Geschlechtskrank-heiten, hrsg. y. J. Jadassohn, Bd 13, T. 2, B., 1927; Pardo Castello V. Pardo O. A. Diseases of the nails, Springfield, 1960; S a m m a n P. D. The nails in diseases, L., 1965.


O. K. Shaposhnikov; E. F. Kotovsky (embr., An., gist.).

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