SPERMATOZOA

From Big Medical Encyclopedia

SPERMATOZOA (Greek sperma, spermat[os] seed + zoon living being + eidos look; synonym: spermiya, seed threads, spermatozoons) — men's sex cells.

Pages are opened by the medical student J. Ham approximately in 1680 and later are described by A. Levenguk., to-ry divided S. on men's and women's. In 1841 Kelliker found out that S., like other cells of an organism, arise from cells. At many animals and the inferior plants of S. is the mobile cell supplied with a flagellum. In the course of S.'s evolution nek-ry backboneless animals and the higher plants lost a flagellum.

Fig. 1. Diagrammatic representation of a structure of a spermatozoon: I \head; II \neck; III \tail; 1 — an acrosome; 2 — a kernel; 3 — a proximal tsentriola; 4 — axial filament; 5 — mitochondrial educations; 6 — terminal filament.

Externally S. of the person is similar to a pin or to a tadpole. It consists of a head, a neck and a tail, or a flagellum, to-ry comes to an end with fine terminal filament or a bunch of their (fig. 1). Total length of a spermatozoon is 50 — 60 microns (a head of 5 — 6 microns, a neck of 6 — 7 microns, a tail of 40 — 50 microns).

Fig. 2. Diffraction patterns of a spermatozoon: and — longitudinal section through a head and a neck of a spermatozoon, x 60 000; — cross section through a head of a spermatozoon in the field of an acrosome, x 65 000: 1 — a kernel; 2 — a proximal tsentriola; 3 — mitochondrions; 4 — a cytolemma; 5 — a nuclear envelope; 6 — an acrosome.

The head has the ovoid form, its end is pointed (fig. 2). The most part of volume of a head is occupied by the homogeneous, unstructured kernel surrounded with a thin coat of cytoplasm. The kernel contains DNA, in a cut the genetic information which is transferred to posterity is coded. Ahead of a kernel the acrosome, or a front hat is located — derivative Golgi's complex. In an upper part of a short neck, adjoining the lower pole of a kernel, the proximal tsentriola is located. The axial filament (an axoneme, or an axial bunch) going along a tail, surrounded with several covers departs from the bottom of a tsentriola. In S.'s neck and an initial part of a tail it is possible to see mitochondrions and groups of membranes of a cytoplasmic reticulum. Mitochondrial educations spiralno surround axial filament almost throughout a tail. Axial filament consists of two central fibrilla surrounded with nine double fibrilla located concentrically. On both sides of a tail over this cover there are two longitudinal tyazh located in the plane of two central fibrilla. The tail comes to an end with fine terminal filament or their bunch. All S. is surrounded with a membrane (cytolemma).

In a form of a head of S. nek-ry researchers distinguish ginospermatozoida, in an oblong head to-rykh there is a stick, and andro-spermatozoa, in a round head to-rykh the point is visible. Assume that from men, in sperm to-rykh androspermatozoida prevail, boys are born more often.

The major biol. properties C. are their mobility and ability to to fertilization (see). Pages are capable to move, bending a tail in the plane of a head. Speed of the movement C. makes 3 mm/min.

In a drop of an ejaculate the movement C. chaotic. In corresponding mobile fiziol. to Wednesday their movement is arranged and is directed against the current (a positive rheotaxsis).

At the movement C. a large amount of energy is spent. The basic biochemical processes in S. providing with their necessary energy are oxidation (see. Redoxreactions ), glycolysis (see), phosphorylation (see). As substrate for implementation of the specified biopower processes serve the chemical connections which are contained in S. and sperm (fructose, glucose, milk to - that, ATP, etc.) and enzymes (see. Sperm ).

Mature S. bear negative electric charge that interferes with their colliding and agglutination, edges is observed at change of pH of the environment in the acid party, in the infected ejaculate under the influence of immune and other factors. The problem of agglutination of S. is important as one of estimated pathogenetic mechanisms infertility (see). The facts testimonial of an important role of an autoallergy in a pathogeny of infertility are found. So, it is proved that the ripening spermatids (see. Spermatogenesis ) and especially S. are antigens for own organism, and at disturbance of a special barrier between blood and contents of seed tubules the autoimmune process leading to an immovability and agglutination of Page develops.

In a vagina of the woman S. keep mobility during 1 — 2,5 hour depending on a condition of the vulval environment (in acid condition of S. perish quicker). In slime of a neck of uterus S.'s mobility remains till 38 — 48 o'clock. There is an opinion that S. continue to move ahead actively and in fallopian (uterine, T.) to pipe. However most of researchers consider that it is connected with reductions of smooth muscles of a uterine tube.

Pages keep the mobility and fertilizing capacity at t ° from 0 to 40 °. Temperature, optimum for S., is 37 °. At a temperature over 40 ° the movement C. stops. At snap-freezing at a temperature of liquid nitrogen (— 192 °) S. do not perish and a long time keep fertilizing capacity. However the sperm stored more than 3 days is not applied to artificial insemination. The optimum environment for S. is isotonic. Hyper - and hypotonic solutions negatively influence S. Dlitelnost's mobility of experience of S. in solutions of electrolytes depends on ionic composition of solutions: the valency of cations is higher, the quicker there occurs agglutination and death of Page.

Direct solar and strong artificial light kills with S. UF-lu-chi with the wavelength of 250 — 270 nanometers are very pernicious for S., however beams with the wavelength of 300 nanometers are almost harmless.

Pages are quite steady against impact of ionizing radiation: doses to 100 000 I am glad (1000 to Gr) do not suppress their activity, however influence of radiation on heredity at the same time is rather big. Perniciously formalin, phenol, lysol, compounds of mercury, potassium permanganate, streptocides, many antibiotics acts on S. However crystal penicillin, streptomycin in bactericidal, and oxytetracycline in bacteriostatic concentration almost do not influence viability of Page.

At pathology in an ejaculate S.'s number decreases, the percent of mobile and morphologically normal forms decreases (see. Sperm ). Sometimes mature S. are absent, and only cells of a spermatogenesis meet (see. Azoospermism ). All S. can be motionless (see. Necrospermia ). In nek-ry cases neither S., nor cells of a spermatogenesis are in sperm (aspermia) or the ejaculate is absent (see. Aspermatism ).



Bibliography: Kagan S.A. Pathology of a spermatogenesis, L., 1969, bibliogr.; M about l-N and r E. The general spermatology, the lane with it., Budapest, 1969, bibliogr.; Vasterling H. W. Praktische Sper-matologie, Stuttgart, 1960, Bibliogr.


V. V. Mazin.

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