Figure 1

Hematoxylin-Eosin stain preparation of lung sections (original magnification 100×) obtained from autopsied rats following injection with a low (100 cfu per injection, panel A), medium (1000 cfu per injection, panel B) and high (10,000 cfu per injection, panel C) inoculum of type 6B pneumococcus in 0.5% low melting-point agarose. As the size of the inoculum increases, there is a clear progression from normal-appearing lung, focal pneumonia and diffuse pneumonia. Shown are 3 slides from a representative experiment.