...vertebrates lack a penis and turn the...
...the scrotum and penis. The internal reproductive...
...rate. The human penis contains the urethra...
...that drain the penis, causing it to...
...engorgement of the penis with blood causes...
...insertion of the penis into the vagina....
...vessels of the penis. This allows blood...
...an erection. The penis of some mammals...
...helps stiffen the penis. A male usually...
...shaft of the penis is covered by...
...head, or glans penis, is covered by...
...to the glans penis and the glans...
...skin on the penis and the labia...
...the vagina and penis for coitus. Vasocongestion...
...erection of the penis and clitoris; enlargement...
...(removal of the penis from the vagina...
...fits over the penis to collect semen....