"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... I. broadest view; II. profile, of k, kernel or nucleus of the head, and m, filamentous body, ending in s, the long slender tail." —Whitney, 1889

Human Spermatozoa

"One of the numberless microscopic bodies contained in semen, to which the seminal fluid owes its vitality,…

Spermatozoa of the salamander (1) and human (2). Labels: a, long pointed head; b, elliptical structure ; c, filiform body; d, fine filament; e, homogeneous membrane.

Spermatozoa of a Salamander and Human

Spermatozoa of the salamander (1) and human (2). Labels: a, long pointed head; b, elliptical structure…

"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... I. broadest view; II. profile, of k, kernel or nucleus of the head, and m, filamentous body, ending in s, the long slender tail." —Whitney, 1889
<p>Illustration of two spermatozoa from an ape.

Spermatozoa of an Ape

"One of the numberless microscopic bodies contained in semen, to which the seminal fluid owes its vitality,…

Spermatozooid, mature male germ cells, of <i>Adiantum capillus-veneris</i>. Also called spermatozoid.

Spermatozooid of the Southern Maidenhair Fern and Venus Hair Fern

Spermatozooid, mature male germ cells, of Adiantum capillus-veneris. Also called spermatozoid.

"Two female sporosacs (degenerate medusae) of Hydraetinia echinata. a, ectoderm; b, endoderm; o, eggcella; g, entric cavity. In A an invagination of the ectoderm, which is more complete in B, represents the rudiment of the sub-umbrella space." &mdash; Encyclopedia Britannica, 1893

Sporosac

"Two female sporosacs (degenerate medusae) of Hydraetinia echinata. a, ectoderm; b, endoderm; o, eggcella;…

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric cavity and its continuations; the lighter shading represents the genital products (ova or sperm). Medualform person still attached by a stalk at the aboral pole to a colony." &mdash; Encyclopedia Britannica, 1893

Sporosae

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric…

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric cavity and its continuations; the lighter shading represents the genital products (ova or sperm). Modified medusiform person, with margin of the disc (umbrella) united above and importforato (mouthless) manubrium." &mdash; Encyclopedia Britannica, 1893

Sporosae

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric…

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric cavity and its continuations; the lighter shading represents the genital products (ova or sperm). Sporosac, with imcomplete extension of the enteric cavity into the umbrella,-rudimentary invagination above to form the sub-umbrella cavity." &mdash; Encyclopedia Britannica, 1893

Sporosae

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric…

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric cavity and its continuations; the lighter shading represents the genital products (ova or sperm). Sporosac with manubrial portion only of the enteric cavity." &mdash; Encyclopedia Britannica, 1893

Sporosae

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric…

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric cavity and its continuations; the lighter shading represents the genital products (ova or sperm). Sporosac without any trace of manubrium." &mdash; Encyclopedia Britannica, 1893

Sporosae

"Gradual degeneration of the medusa bud into the form of a sporosae. The black represents the enteric…