The =uterus masculinus= or =prostatic utricle= is a rudimentary
structure of variable size and form, situated centrally on the posterior
part of the dorsal surface of the bladder. When well developed, it
consists of a median flattened tube, some three or four inches (ca. 7.5
to 10 cm.) long, and about half an inch (ca. 1 to 1.5 cm.) wide, the
anterior part of which lies in the urogenital fold and gives off two
slender processes or cornua; the latter curve forward and outward in the
fold a variable distance, being sometimes traceable as far as the
anterior end of the ampulla of the vas deferens. The posterior extremity
of the tube passes under the isthmus of the prostate, and opens into the
urethra on the summit of the colliculus or joins an ejaculatory duct. It
has a muscular coat and a mucous lining. In many cases it consists
merely of a very small central tubule with a blind anterior end, or a
band, not at all sharply marked off from the adjacent tissue; in other
cases it cannot be recognized. It is interesting chiefly as being a
remnant of the ducts of Müller and the homologue of the uterus and
vagina.