Penis in males is the main copulatory organ. It carries sperms and urine. It delivers sperms into the female body so that the sperms can fertilize the ovum. Penis is able to enter the female vagina because it is made up of three erectile tissues. These are two corpora cavernosa and one corpora spongiosum through which urethra passes. This erectile tissue becomes engorged with blood and thus the penis becomes hard and stiff. Such erectile tissue is seen in females too and is known as clitoris. The erectile tissue present is corpora cavernosa. Clitoris is present at the anterior junction of labia minora. Hence clitoris is homologous to the penis. Homologous organs are those organs that are similar in embryonic origin but different in function.