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Examine the prostatic part of the urethra which begins at the internal urethral orifice and runs inferiorly through the prostate gland to the level of the superior fascia of the urogenital diaphragm. The prostatic part is the widest part of the urethra. On the posterior wall of the prostatic urethra, identify the elevation called the seminal colliculus, which lies on the urethral crest [in higher magnification]. On the anterior surface of the seminal colliculus, identify the central opening of the prostatic utricle [located below the tip of the probe]. This blind-end pouch is a homologue of the vagina in the female. Attempt to identify the openings of the two ejaculatory ducts.
 
Lateral to the seminal colliculus, identify two prostatic sinuses. The prostatic ducts (20-30 in number) that open to the prostatic sinuses secretes the alkaline fluid, a product of the prostate gland.

Links and References:
Grant's: 3.28
Netter (1ed.): 347, 362 (2ed.): 343, 358
Rohen/Yokochi: 317, 318, 319