spermatozoon


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spermatozoon:

see spermsperm
or spermatozoon
, in biology, the male gamete (sex cell), corresponding to the female ovum in organisms that reproduce sexually. In higher animals the sperm is produced in the testis of the male; it is much smaller than the ovum and consists primarily of a head,
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Spermatozoon

 

the male sexual cell in animals.

In all vertebrates and most invertebrates a flagellum, or tail, enables the spermatozoa to move forward. The spermatozoa of some worms, myriopods, crustaceans, mites, and ticks are tailless and are characterized by a wide variation in structure and by amoeboid movement. Spermatozoa range in length, according to species, from tens to hundreds of micrometers; the spermatozoa of insects may reach several millimeters in length.

Spermatozoa with tails have a comparatively short head that may be spherical, conical, or hooked in shape. A nucleus containing condensed chromatin is found in the head. At the head’s anterior end there is an acrosome containing lysins. Below the head there is a thinner middle piece that ends in a threadlike tail. In most animal species the middle piece is short and encloses a basal granule (centriole) consisting of nine triplets of short microtubules arranged in a ring and surrounded by a halo of four to ten large mitochondria.

Extending from the basal granule is an axial filament, or axo-neme, which by contracting enables the flagellum to beat and the spermatozoon to move. The ultrastructure of the axial filament is virtually the same in all spermatozoa and is similar to that of cilia. A filament consists of fibrils (microtubules 200–250 angstroms in diameter), two of which lie in the center surrounded by a ring of nine peripheral fibril doublets (9 + 2). Sometimes nine additional fibrils are found outside the doublets (9 + 9 + 2). Flagellate peripheral fibrils are transformed directly into microtubules of the basal granule, and the central fibrils remain free. Proteins similar to actin and myosin (found in skeletal muscles) and capable of splitting ATP are found in flagellate axial filaments in fibrils and in structures directly associated with fibrils.

In insects the head of a spermatozoon is very elongated and sometimes spirally coiled, extending almost imperceptibly into a long tail. Much of the tail contains a distinctive structure of mitochondrial origin called a mitochondrial helix.

In many animals several types of spermatozoa are formed in the testes. Most are atypical, resulting from spermatogenic disturbances primarily occurring during meiosis. These spermatozoa apparently cannot fertilize ova.

REFERENCES

Wilson, E. Kletka i ee rol’ v razvitii i nasledstvennosti, vol. 1. Moscow-Leningrad, 1936. (Translated from English.)
Rukovodstvo po tsitologii, vol. 2. Moscow-Leningrad, 1966.
Hancock, J. L. “The Ultrastructure of Mammalian Spermatozoa.” In Advances in Reproductive Physiology. London, 1966.

L. V. DANILOVA

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

spermatozoon

[spər‚mad·ə′zō·ən]
(histology)
A mature male germ cell. Also known as sperm.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

spermatozoon

any of the male reproductive cells released in the semen during ejaculation, consisting of a flattened egg-shaped head, a long neck, and a whiplike tail by which it moves to fertilize the female ovum
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Therefore, it is possible that sperm water fluxes triggered by hypo- and hyperosmotic shock may be mediated by aquaporins of the spermatozoon plasma membrane (Alavi and Cosson, 2006).
Van Steirteghem, "Pregnancies after intracytoplasmic injection of single spermatozoon into an oocyte," The Lancet, vol.
Ultrastructural and cytochemical studies of the spermatid and spermatozoon of Culex quinquefasciatus (Culicidae).
2) induction of the acrosome reaction, and 3) fusion of the spermatozoon and the oocyte.
Dimensions that define a normal spermatozoon are based on sperm that have been fixed and stained using the Papanicolaou method.
The uneven contour of the head portion was evident in scanning electron microscopic aspects of the spermatozoon. No acrosomal structure was detected in the head.
There is little information available on the mechanism whereby the spermatozoon could influence embryo development.
Electron microscope study on the spermatozoon of the liphistiid spider Heptathela kimurai.
The final step in the developmental process, termed spermiogenesis, is the conversion of a haploid round spermatid to a polarized, flagellated, motile spermatozoon or sperm (see Figure 1).
(1998) documented positively significant correlation between body weight and seminal volume, pH, and abnormal spermatozoa rate, whereas a negative correlation exits between body weight and motility, spermatozoon concentration and live spermatozoon rate in poultry.
Thus, it should be expected that a high rate of these patients will be candidates for ART because with intracytoplasmic sperm injection (ICSI) as the ultimate means, an oocyte needs only one viable spermatozoon for fertilization.
reported that spermatozoon ROS content directly influences the levels and locations of tyrosine phosphorylation and then enables the spermatozoa to undergo acrosome reaction [14].