Fig. 1.-Normal male urethra. Retrograde ureth- rogram shows smooth margins of urethra with gentle taperIng in region of membranous urethra (white arrow). Note filling defectin prostatic urethra caused by verumontanum (black arrow). Received November 30, 1987; accepted after revision February 25, 1988. I Department of Radiology, Columbia-Presbyterian Medical Center, 622 W. 1 68th St., New York, NY 1 0032. Address reprint requests to E. S. Amis, Jr. 2 Department of Radiology, Rhode Island Hospital, Providence, RI 02903. 321 AJR 151:321-324, August 1988 0361-803X/88/1512-0321 C American Roentgen Ray Society Pictorial Essay i:.;;::. ,.. Y. . Radiology of Male Periurethral Structures Edward S. Amis, Jr.,1Jeffrey H. Newhouse,1 and John J. Cronan2 Interpretation of male urethrograms is usually straightfor- ward [1 ]. However, the urethra is surrounded by several structures that may be opacified during urethrography and produce confusing images. This essay will illustrate these structures and discuss their clinical importance. Anatomy The male anterior urethra (Figs. 1 and 2) extends from the external meatus to the urogenital diaphragm and courses through the corpus spongiosum. It is lined by the glands of Littre, whose secretions lubricate the urethra. The accessory sex glands of Cowper are paired structures that lie on either side of the membranous urethra; their ducts extend approxi- mately 2 cm caudally and enter the proximal bulbar urethra. The verumontanum lies in the posterior wall of the prostatic urethra; it is a small mound of tissue whose distal end marks the beginning of the membranous urethra. A small saccular depression in the center of the verumontanum, the utricle, represents a mUllerian remnant. Just distal to the utricle are the orifices of the paired ejaculatory ducts, which bifurcate at V h m co(p,s spong,osw Fig. 2.-Male urethra and periurethral structures (ejac. = ejaculatory).