Module 8: Figure sperm structure
Structure of a typical mammalian spermatozoon.
The head of the sperm has an acrosomal cap, which contains the acrosome that is released during the acrosomal reaction at the beginning of fertilization. Most of the head is taken up by the large nucleus. The connecting piece (also known as the neck region) attaches the head to the long flagellum that is divided into three sections: the middle piece, the principal piece and the end piece. All the mitochondria in the sperm are concentrated in the middle piece, where they form a highly ordered sheath wrapped around the flagellum (for details of this section, see Module 8: Figure sperm connecting piece). Reproduced from William Bloom and Don W. Fawcett, A Textbook of Histology, 10th edition (W.B. Saunders, 1975), © 1975 by W.B. Saunders Company, reproduced by permission of Edward Arnold; see Bloom and Fawcett 1975.