Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
pages 42
| are produced, viz., the mature ovum and three polar bodies, each of which contains two chromosomes, i.e., one-half the number present in the nuclei of the somatic cells of members of the same species. The nucleus of the mature ovum is termed the female pronucleus. |
| 3. The Spermatozoön |
| The spermatozoa or male germ cells are developed in the testes and are present in enormous numbers in the seminal fluid. Each consists of a small but greatly modified cell. The human spermatozoön possesses a head, a neck, a connecting piece or body, and a tail (Fig. 6). |
 |
FIG. 6– Human spermatozoön. Diagrammatic. A. Surface view. B. Profile view. In C the head, neck, and connecting piece are more highly magnified. (See enlarged image) |
| The head is oval or elliptical, but flattened, so that when viewed in profile it is pear-shaped. Its anterior two-thirds are covered by a layer of modified protoplasm, which is named the head-cap. This, in some animals, e. g., the salamander, is prolonged into a barbed spear-like process or perforator, which probably facilitates the entrance of the spermatozoön into the ovum. The posterior part of the head exhibits an affinity for certain reagents, and presents a transversely striated appearance, being crossed by three or four dark bands. In some animals a central rodlike filament extends forward for about two-thirds of the length of the head, while in others a rounded body is seen near its center. The head contains a mass of |