Hairlike structures are flagella of new rat sperm.
Even with all that's changed in the world, today's Casanovas have few more contraceptive choices for themselves than the original did. It's primarily abstinence, withdrawal, or condoms for men, whether they have many partners or just one. A surgical approach to contraception for men, vasectomy, which became available in the early part of the 20th century, presents the only notable addition. In contrast, the number of contraceptive choices available to women has dramatically increased during this century, especially forms of so-called hormonal contraception such as birth control pills. Some women are uncomfortable with or can't take hormonal contraception.