Navicular fossa of male urethra
The navicular fossa is a short dilated portion of the male urethra within the glans penis just proximal to the external urethral meatus. The roof of the fossa is especially dilated, forming a lacuna; medical instruments being inserted into the male urethra should initially be directed towards the floor of the fossa' so as not to get snagged at the fossa. It is one of three dilations of the male urethra.'
The wall of the navicular fossa is the only part of the urethra that is lined with stratified squamous epithelium.
During development, the glans of the penis is initially solid but cannulates to give rise to the navicular fossa.