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Structure of Human Sperm

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The sperm or male gamete is a microscopic cell. It consists of four parts.
  • Head 
  • Neck
  • Middle Piece
  • Tail



HEAD
Human sperm has a flat and oval head. It has a large, compact nucleus and small acrosome at the tip of the nucleus. Acrosome is formed of Golgi apparatus. It contains hydrolytic enzymes. The nucleus contains haploid set of chromosomes. The head is covered by a fibrillar sheath. The nucleus consists of condensed DNA and basic proteins.

NECK
The neck is very short. It contains two centrioles – one proximal and one distal. The proximal centriole is towards nucleus and plays a key role in the first cleavage of the zygote. The distal centriole is towards tail and gives rise to axial filament of the sperm, which consists of 9 – sets of microtubules triplet arranged in ring.

MIDDLE PIECE
It is cylindrical. It contains many mitochondria coiled tightly around the axial filament, called mitochondrial spiral. The mitochondria provide energy for the movement of sperms in the female genital tract.

TAIL
The tail is long, slender, tapering and strengthed by axial filament.  It is formed of cytoplasm. The axial filament projects behind as end piece.

The entire sperm is enclosed by a plasma membrane. The sperm swims with the help of tail.

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