EM 362 Spermatozoa

Spermatozoa

Scanning electron microscopy (SEM) of spermatozoon on the surface of the uterine epithelium.

• Spermatozoon - male gamete on the uterine surface
  • Head (orange) - contains the compact nucleus
  • Neck (cyan) - short segment that contains the centrioles
  • Tail (green) - long flagellum that contains the axonemal complex that forms its core
    • Middle Piece (light green) - initial region surrounded by a helical sheath of tightly packed mitochondria
    • Principal Piece (dark green) - axoneme surrounded by the fibrous sheath
    • End Piece (dark green) - only contains the axoneme
• Uterine Epithelium - lines the inner surface of the uterus (endometrium)
  • Ciliated Cells (yellow) - covered with long cilia
    • Play a role in the movement of substances within the uterine cavity
  • Secretory Cells (tan) - non-ciliated cells covered with short microvilli
    • Secrete a variety of substances, including glycogen, proteins, and lipids, to nourish the embryo and support early pregnancy
    • Each has a centrally placed vestigial cilium (purple)

Courtesy of Pietro M. Motta, Department of Anatomy, University of Rome, Rome, Italy.