Mean pulmonary CFU counts in sensitized and non-sensitized rabbits. At necropsy, multiple samples of the right lung, left lung, caseous center and cavitary wall were obtained. The log CFU count/gram of tissue was determined after homogenization and plating dilutions. Non-sensitized rabbits had greater CFUs in the lung parenchyma bilaterally. Non-cavitary caseous centers in non-sensitized rabbits had fewer CFUs compared to sensitized animals. Cavitary lesions were uniquely observed in sensitized rabbits. P values, for which none achieved significance, are based on average CFU counts of sensitized versus non-sensitized rabbits at each comparable intrathoracic site. Error bars represent standard error of the mean.