FIG. 5.

Representative transmission electron micrographs of respiratory epithelial cells infected with GBS type III strain M781 grown at a cell mass doubling time of 1.8 h with 0% (A and B) and 5% (C and D) DO₂. Although GBS cells grown under the two conditions apparently adhere to the respiratory cells (A and C), the number of GBS cells located intracellularly (indicated by arrows) is high only when GBS is grown with 5% DO₂ (D). Bars: 500 nm (A), 500 nm (B), 1 μm (C), and 500 nm (D). Magnification: ×15,000 (A), ×10,000 (B), ×6,500 (C), and ×10,000 (D).