Electron microscopic demonstration of close contact between intracellular mycobacteria and the phagosomal membrane

Ultrathin sections of granulomatous lung lesions of tuberculous mice were subjected to electron microscopy to observe the intraphagosomal behaviour of mycobacteria. The close contact between the external surface of the bacterial cell wall and the phagosomal membrane was a characteristic feature, This was also observed with ultrathin sections of a mycobacterial specimen harvested from the homogenate of such lungs. The significance of this event was interpreted in relation to the mechanism of mycobacterial infection.