Corpus spongiosum

Erectile tissue body in both male and females, the corpus spongiosum begin development as paired erectile tissue structures.  In females the corpus spongiosum remain two separate bodies that are just lateral to the labia minora.  They sit on either side of the vagina and are collectively called the bulb of the vestibule.  The vestibule is that part of the vagina that contains both the vaginal opening and the urethral opening.  

In males the corpus spongiosum fuse together in the midline, form and surround the penile urethra, and the fused bodies are called the bulb of the penis.