Homogenous tubular containing either air or fluid mainly for the process of exchanging their products between each other

• Formed of numerous minute canals
  • nephron joins to form
    • renal pelvis , ureter
  • seminiferous tubules joins to form
    • vas deferens , epididymis , rete testis
  • alveoli joins to form
    • bronchioles , bronchi , trachea
  • exocrine ducts
  • villi
    • chorionic villi
    • gastric villi
      • microvilli
    • renal villi
  • capillaries
    • glomerular capillaries
    • fenestrated capillaries
    • sinusoidal capillaries

• Containing a circular group of epithelial cells
  • Follicle
    • Thyroid Follicle
    • Ovarian Follicle
• Juices
  • ग्रन्थि , गदूद , GLANDULE, Kernel, Emunctory, Almond, Bur, Sweet-bread, Nut.