EM 395 Testis

Testis

Scanning electron microscopy (SEM) of several cross-sections of seminiferous tubules within the testis.

Seminiferous tubules are the site of sperm production (spermatogenesis) in the testis. Tightly coiled tubules, which, if uncoiled, would measure several meters in length. They are lined with a layer of cells called the germinal epithelium.

• Germinal Epithelium (green) - cannot distinguish the identity of most cells
  • Spermatogenic Cells - developing sperm cells at various stages of spermatogenesis (spermatogonia, spermatocytes, spermatids, and mature spermatozoa)
    • Sperm Tails (blue)
  • Sertoli Cells - provide physical and nutritional support for developing sperm cells
    • Tall, columnar cells that extend from the basal lamina to the lumen of the seminiferous tubules
    • Tight junctions between Sertoli cells form the blood-testis barrier
• Interstitial Tissue (tan) - fills the spaces between the seminiferous tubules
  • Leydig Cells (or interstitial cells) - located in the interstitial spaces between the seminiferous tubules
    • Primarily responsible for producing testosterone
    • Luteinizing hormone (LH) from the pituitary stimulates the production of testosterone
  • Blood vessels, lymphatic vessels, and nerve fibers
  • Macrophages - principal immune cells in the testis
    • Immune surveillance
    • Involved in the regulation of Leydig cells

Any disruption of the functioning of the seminiferous tubule may affect male infertility.