[Anatomy and sonography of the prostate].

According to the data of John McNeal, a three-dimensional model of the prostate is presented; this is based on his serial sections of the prostate in different, carefully selected planes. The urethra is the anatomical reference point. The proximal urethral segment is covered by the transition zone, periurethral tissue and the preprostatic sphincter. The two main glandular regions of the prostate are the central zone and the peripheral zone. Carcinoma arises mainly in the peripheral zone, while benign prostatic hyperplasia (BPH) arises mainly in the transition zone.