Urethra

Abstract

The male urethra may be subdivided into the anterior and posterior urethra. Starting at the bladder neck, the posterior urethra is lined with transitional epithelium and consists of the prostatic urethra and the membranous urethra. The prostatic urethra is characterized by the orifices of numerous prostatic ductules and by the verumontanum or seminal collicle at its posterior aspect. The latter represents a small mound that carries the orifices of the ejaculatory ducts at its lateral aspects and the prostatic utricle as a blindly ending diverticulum in its center. The membranous urethra crosses through the urogenital diaphragm, to connect the intracorporal part of the urethra to the extracorporal or anterior part. The anterior urethra, in turn, is lined with squamous cell epithelium and completely surrounded by the corpus spongiosum. It divides into the bulbous urethra and the pendulous urethra. The bulbous urethra is characterized by its covering by the bulbocavernosus muscle inferiorly, and by the openings of the bulbourethral or Cowper's gland ducts. Cowper's glands are up to 4.5 cm long. In addition, numerous small lacunar Littre's glands open into the anterior urethra. At the distal end of the urethra, close to its orifice, the navicular fossa represents a bulbus dilation of about 1 cm in length (Barbaric 1994).