→ The structure of a sperm is a microscopic structure composed of a head, neck, a middle piece and a tail.
→ A plasma membrane envelops the whole body of sperm.
→ The sperm head contains an elongated haploid nucleus, the anterior portion of which is covered by a cap-like structure, acrosome.
→ The acrosome is filled with enzymes that help fertilisation of the ovum.
→ The middle piece possesses numerous mitochondria, which produce energy for the movement of tail that facilitate sperm motility essential for fertilisation.
→ The human male ejaculates about 200 to 300 million sperms during a coitus of which, for normal fertility, at least 60 per cent sperms must have normal shape and size and at least 40 per cent of them must show vigorous motility.
→ Sperms released from the seminiferous tubules, are transported by the accessory ducts. Secretions of epididymis, vas deferens, seminal vesicle and prostate are essential for maturation and motility of sperms.
→ The seminal plasma along with the sperms constitute the semen.
→ The functions of male sex accessory ducts and glands are maintained by the testicular hormones (androgens).