spermatozoon

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The mature fertilizing gamete of a male organism, usually consisting of a round or cylindrical nucleated cell, a short neck, and a thin motile tail. Also called sperm cell, zoosperm.

Century Dictionary and Cyclopedia

1. n. One of the numberless microscopic bodies contained in semen, to which the seminal fluid owes its vitality, and which are the immediate and active means of impregnating or fertilizing the ovum of the female; a spermatic cell or filament; a spermatozoan or spermatozooid. Spermatozoa are the vital and essential product of a spermary, male gonad, or testis, as ova are of the ovary or female gonad; their production, or the ability to produce them, is the characteristic distinction of the male from the female organism, whatever their size or shape or other physical character, and however various may be the organ in which they are produced. Spermatozoa, like ova, have the morphological value of the cell; and a spermatozoön is usually a cell in which a cell-wall, cell-contents, and cell-nucleus, with or without a nucleolus, may be. distinguished. The form may be spherical, like the ovum, and indistinguishable therefrom by any physical character; more frequently, and especially in the higher animals, these little bodies are shaped like a tadpole, with a small spherical or discoidal head, a succeeding rod-like or bacillar part, and a long slender tail or caudal filament, capable of spontaneous vibratile movements, by means of which the spermatozoa swim actively in the seminal fluid, like a shoal of microscopic fishes, every one seeking, in the passages of the female into which the fluid has been injected, to discover the ovum in which to bury itself, in order to undergo dissolution in the substance of the ovum. They are smaller than the corresponding ovum, and several or many of them may be embedded in one ovum. The actual union of spermatozoa with an ovum, and fusion of their respective protoplasms, is required for impregnation, and is the consummation of sexual intercourse, to which all other acts and processes are simply ancillary or subservient. Spermatozoa may be killed by cold, or chemical or mechanical injury, like any other cells. These bodies, very similar to various animalcules, were discovered and named spermatozoa by Leeuwenhoek in 1677; they were at first and long afterward regarded as independent organisms, variously classed as parasitic helminths or infu-sorians—such a view being held, for instance, by Von Baer so late as 1827 or 1835. Von Siebold, who found them in various vertebrates, called them spermatozooids. Their true nature appears to have been first recognized by Kölliker. Spermatozoa or their equivalents are diagnostic of the male sex under whatever conditions they exist, whether in male individuals separate from the female, or in those many hermaphrodite animals which unite the two sexes in one individual; and the organ which produces them is invariably a testis or its equivalent spermary, of whatever character. The male elements of the lowest animals, however, as Protozoa, do not ordinarily receive the name spermatozoa, this being specially applied to the more elaborate male cells of the character above described. The origination of spermatozoa has of late years been the subject of much research and discussion; the details of the process, as observed in different animals, or under different conditions of investigation, together with conflicting doctrinal conclusions, have occasioned a large special vocabulary. See many words preceding and following this one.
2. n. A genus of animalcules.

Wiktionary

1. n. cytology The reproductive cell or gamete of the male, carried in semen, that fertilizes the ovum to produce the zygote.

GNU Webster's 1913

1. n. (Biol.) Same as spermatozoid.

WordNet 3.0

1. n. the male reproductive cell; the male gamete