In his memoirs, legendary 18th-century lover Giacomo Casanova recommended the use of condoms—which he called “English riding coats”—to protect against unwanted pregnancies.
As germ cells mature, they move to the center of seminiferous tubules (about 150 microns across). Hairlike structures are flagella of new rat sperm. University of Kansas Medical Center
Human sperm, showing DNA (blue), membrane (red), and proteins (green) used to penetrate the egg.
Log in
Subscribers, enter your e-mail address for full access to the Science News archives and digital editions.