Anatomy of the Testis

The Testis

• The testis is surrounded by a dense connective tissue capsule called the tunica albuginea.
• The tunica albuginea divides the testis into approximately 250 pyramidal compartments or testicular lobules.
• Each lobule contains:
  • Connective tissue with endocrine interstitial cells (Leydig cells) that secrete testosterone.
  • One to four highly convoluted seminiferous tubules where sperm production occurs.

Functions of the Testis

• Production of spermatozoa.
• Production of male sex hormones, mainly testosterone.

Germinal Epithelium

• The germinal epithelium is primarily composed of sex cells and a few supporting cells (Sertoli cells).
• The cells lie on a basement membrane surrounded by a connective tissue sheath.

Sex Cells (Spermatogenic Cells)

• Form 4-8 layers in the seminiferous tubules.
• Differentiate progressively from the base to the lumen of the seminiferous tubule.
• Cells include:
  • Spermatogonia
  • Primary spermatocytes
  • Secondary spermatocytes
  • Spermatids
• These cells change to spermatozoa through spermiogenesis.

Sertoli Cells

• Tall columnar cells with bases resting on the basement membrane.
• Apical cell membranes are highly folded and project into the lumina of the seminiferous tubules.
• Cells have pale irregular nuclei with a large nucleolus.
• Lateral cell membranes of adjacent Sertoli cells form occluding junctions, establishing a blood-testis barrier.

Functions of Sertoli Cells

• Provide physical and nutritional support to developing germ cells.
• Perform phagocytosis of cytoplasm eliminated during spermiogenesis.
• Establish a blood-testis barrier by forming zonulae occludentes between adjacent Sertoli cells.

Interstitial Connective Tissue

• Loose connective tissue containing macrophages, fibroblasts, and mast cells.

This quiz covers the structure and functions of the testis, including the tunica albuginea, testicular lobules, and seminiferous tubules. It also explores the production of spermatozoa and testosterone.