prostatic utricle 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 or uterus masculinus or (in older literature) vesicula prostatica. prostatic utriclevesiculae seminales and ampullæ of ductus deferentes, seen from the front.the male urethra laid open on its anterior (upper) surface.detailsprecursorremnant of paramesonephric ductidentifierslatinutriculus prostaticus, utriculus masculinus, vagina masculina, sinus pocularista98a09.4.02.009ta23449fma19702anatomical terminology 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. dissection of prostate showing prostatic utricle opening into the prostatic urethra. function the prostatic utricle is the homologue of the uterus and vagina, usually described as derived from the paramesonephric duct, 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."