The =prostate= (Prostata) is a musculo-glandular organ which lies on the
neck of the bladder and the beginning of the urethra, beneath the
rectum. It consists of two lateral lobes and a connecting isthmus.
The =lateral lobes=, right and left (Lobus dexter et sinister), are
somewhat prismatic in form, and are directed forward, outward, and
somewhat upward. The antero-internal surface of each lobe is concave and
partly embraces the corresponding vesicula seminalis. The dorsal surface
is concave and is in relation with the rectum. The ventral surface is
convex and lies on the obturator internus muscle and fat. The apex is
pointed and lies near the posterior end of the superior ischiatic spine.
The =isthmus= is a thin, transverse band, about four-fifths of an inch
(ca. 2 cm.) wide. It lies over the junction of the bladder with the
urethra, the uterus masculinus, the terminal parts of the vasa
deferentia, and the necks of the vesiculæ seminales. Dorsally it is
partly covered by transverse fibers of the urethral (Wilson’s) muscle.
=Structure.=—The prostate is inclosed in a fibro-muscular =capsule=,
which sends thick, somewhat radially arranged =trabeculæ= into the gland
substance, dividing it into spheroidal or ovoid =lobules=. The lobules
contain a central space in which the prostatic secretion (Succus
prostaticus) collects. The walls of these spaces are pouched out to form
tubular diverticula, and the latter present saccular dilatations. These
cavities are all lined by cubical epithelium. There are 15 to 20
=prostatic ducts= (Ductus prostatici) on either side, which perforate
the urethra and open lateral to the colliculus seminalis. The
=blood-supply= is derived from the =internal pudic artery=.
The surface of the prostate is commonly tuberculate in old subjects,
and amyloid bodies and calcareous concretions may be found in it.