Spermatozoon Structure and Function

Spermatozoon (Male Gamete)

• Spermatozoon, also known as sperm or sperm cell, is the male gamete.
• A mature spermatozoon has a specific structure, including a head, neck, middle piece, and tail.

Spermatozoon Structure

• Head: Contains a densely-packed haploid nucleus and an acrosomal cap.
  • The head is typically ovoid or piriform in shape.
  • The acrosomal cap contains enzymes, such as acrosin and hyaluronidase.
  • The acrosomal cap is about half the length of the head.
• Neck: A short constriction connecting the head and middle piece.
  • The neck contains centrioles, which are essential for cell division.
  • The length is approximately 0.3 µm.
• Middle Piece: Contains numerous mitochondria arranged in a spiral sheath.
  • The mitochondria provide energy for the movement of the sperm.
  • The middle piece is about 7 µm long.
• Tail: A long, slender tail that extends from the middle piece.
  • The tail has a core of microtubules called the axoneme, surrounded by plasma membrane.
  • The tail propels the sperm forward.
  • The tail is around 40 µm long and 0.5 µm wide.

Ovum (Female Gamete)

• The ovum, or egg cell, is the female gamete.
• It's a large, rounded cell with a distinctive structure.

Ovum Characteristics

• Size: Large, approximately 200 µm in diameter.
• Shape: Rounded.
• Motility: Immotile.
• Viability: Viable for approximately 24 hours after ovulation.
• Yolk: Rich in nutritive yolk.
  • The yolk is composed primarily of lecithin.
  • The yolk content is isolecithal, which indicates a uniform distribution of yolk throughout the cytoplasm.

Ovum Structure

• Nucleus: Contains a haploid nucleus (23 chromosomes) and a nucleolus.
• Nucleolus: Also known as the germinal spot.
• Cytoplasm: Contains various organelles (as well as formative yolk) and nutritive yolk.
• Zona Pellucida: An external layer composed of glycoproteins.
• Corona Radiata: A layer of cells surrounding the zona pellucida, protecting the ovum.
• Cortical Granules: Located within the cytoplasm, contain enzymes that help prevent polyspermy.

Sperm and Egg Summary

• The mature spermatozoon has a specific structure that enables it to move and fertilize an ovum.
• The ovum is large and immobile, containing nutrients and reserves needed for early embryonic development.