It is enlarged to form a bulb at the base of the penis and again at the end of the penis to form the navicular fossa (Fig. 5.45B). The two bulbo-urethral glands in the deep perineal pouch are part of the male reproductive system and open into the bulb of the spongy urethra. The external urethral orifice is the sagittal slit at the end of the penis.