Prostate gland

The prostate (Figs 4.92, 4.93; see also Fig. 4.81) lies below the bladder. The urethra and the two ejaculatory ducts pass through the prostate. The ejaculatory ducts drain into the prostatic part of the urethra. The prostate has a base and an apex – the base, which is the upper surface, is fused with the bladder neck and the blunt apex projects downwards. The posterior surface of the prostate has a groove which is normally felt on rectal examination. When the prostate enlarges this groove disappears. Veins of the prostate drain into the prostatic venous plexus around the gland. This in turn is connected to the vertebral venous plexuses (Batson's veins). There are no valves in these connections. Malignant tumours of the prostate spread through these veins into the vertebral column.

The prostate contains fibromuscular tissues and glands which open into the urethra. The prostate has a central and a peripheral zone which respectively have approximately 25% and 75% of the glandular tissue each. The wedge-shaped central zone which forms the base of the gland contains small glands which are not coiled. The ducts of the central zone open at apex on the verumontanum (see prostatic urethra, p. 114). The peripheral zone forming the lower part of the gland surrounds the central zone but does not reach the upper part of the gland. Glands of the peripheral zone are long and tortuous and the ducts open into the prostatic sinuses. Prostatic secretion added to the seminal fluid is important for the survival of spermatozoa.

Benign hyperplasia/hypertrophy of the prostate is extremely common in men above the age of 60. It is the central zone of the prostate which is usually affected by benign hypertrophy. The peripheral zone is almost exclusively the site of origin of carcinoma of the prostate. See Clinical box 4.22.