The prostate is a heterogenous organ located within the pelvic cavity anterior to the rectum. It consists of both glandular and fibrous components, all of which are enclosed by a common capsule. In recent decades, the development of transrectal ultrasonography has provided an effective tool for prostate examination. The technique delineates normal intraprostatic anatomy and is also useful for the detection of both benign and neoplastic prostate disease.
The embryologic development of the prostate is highly dependent on androgenic hormones. The organ begins to form at about the eleventh week of gestation (7:33-34). Stimulated by testosterone, multiple solid outgrowths emerge from the urethral epithelium about the entrance of the mesonephric ducts. These outgrowths eventually form the prostate's glandular elements. While the mesenchyme into which they grow contributes to the prostatic capsule, the Wolffian duct forms the stroma and epithelium of the intraprostatic vas deferens and ejaculatory ducts (6:8-9).
Upon gross examination, the prostate resembles an inverted cone measuring about 4.1 cm wide, 3.3 cm long, and 2.4 cm deep. Normally, it weighs approximately 20 grams. The organ is bordered posteriorly by the rectum, anteriorly by the pubis symphysis, and laterally by the levator ani and obturator internus muscles. Moreover, it lies posterior to the urogenital diaphragm and inferior to the bladder. It is positioned such that the base of the cone abuts the bladder while its apex points caudally (5:274).
Although the different elements of the prostate are tightly fused, they may be divided into distinct anterior, posterior, middle, and lateral lobes. The organ's nonfunctional anterior lobe consists primarily of fibromuscular stroma. In contrast, the middle, the posterior, the two lateral lobes, and the transition zones comprise the glandular portion of the prostate. The middle lobe consist...