Prostatic utricle

The prostatic utricle (Latin for "small pouch of the prostate") is a small indentation in the prostatic urethra, at the apex of the urethral crest, on the seminal colliculus (verumontanum), laterally flanked by openings of the ejaculatory ducts. It is also known as the vagina masculina, uterus masculinus or (in older literature) vesicula prostatica.

Structure
It is often described as "blind", meaning that it is a duct that does not lead to any other structures. It tends to be about one cm in length. It can sometimes be enlarged. The utricle is deemed enlarged if it allows insertion of a cystoscope at least 2 cm deep. This is often associated with hypospadias.



Function
The prostatic utricle is a remnant that is homologous to the female uterus (including the cervix) and vagina, usually described as derived from the paramesonephric ducts, although this is occasionally disputed.

In 1905, Robert William Taylor described the function of the utricle: "In coitus it so contracts that it draws upon the openings of the ejaculatory ducts, and thus renders them so patulous that the semen readily passes through."