Man has three types of accessory glands. The secretion of these glands take part in semen formation :
(1) Prostate Glands : It is large lobulated, gland situated at the base of urethra. This gland secrets slightly white alkaline fluid which forms 25-30% of total semen and contains phosphates, citrates, lysozyme, fibrinolysin, spermin etc. It activates the sperms, provides nutrition and prevents coagulation of semen.
(2) Seminal Vesicle : These are one pair situated between the bladder and rectum. It is muscular and sacculated glands. These glands secrete alkaline fluid forming 60% of total semen. It contains prostaglandins and fructose. Fructose provides energy to sperms whereas prostaglandin stimulates vaginal contractions to help in fusion of gametes.
(3) Cowper Glands or Bulbourethral Gland : These glands secrete a viscous, sticky alkaline fluid during copulation which lubricates the penis and removes the acidity
of vaginal passage to protect the sperms. In this way we can conclude that secretum of accessory glands help in semen formation and reproductive process.