Describe the role of the following in human beings:
(i) Seminal vesicles (ii) Prostate glands.
(i) Seminal vesicles : It secretes alkaline secretions which lower the -pH of the semen and provide nourishment. It also store sperms in some lower vertebrates and invertebrates (earthworm, insects).
(ii) Prostate glands: The secretions of these glands keep the sperm active and mobile. It secretes alkaline fluid comprising up to a third of semen volume and assists sperm motility.