Figure 4: TEM images of Bi-stained sections of bacterial cells associated with the immature sheath prepared at days 2 and 3. (A) A cross-section of the cell associated with an immature fibrous sheath having electron-dense metal deposits on the outer surface (day 2). (B) A longitudinal section of the cells surrounded by an immature fibrous sheath (day 2). Details of assemblage of microfibrils are shown in inset. (C) A cross-section of the cell associated with an immature fibrous sheath with a high electron density attributable to a heavy deposition of metals (day 3). (D) A longitudinal section of the linked cells surrounded by an immature sheath with a heavily electron-dense fibrous outer surface (day 3). Details of the electron-dense fibrous assembly are shown in inset.