Fig 1. Extensive lesions suggestive of tuberculosis were observed in lymph nodes from calves naturally infected with M. bovis and compared to lesions found in adult cattle.

(A) Mediastinal lymph node with severe granulomatous lymphadenitis and (B) H&E, 40x showing a granuloma encapsulated by connective tissue and abundant necrosis and mineralization from a 3-year-old Holstein-Friesian dairy cow. (C) Mediastinal lymph node with extensive areas of caseous necrosis and microhemorrhages and (D) H&E, 40x showing a granuloma without connective tissue and abundant necrosis and mineralization from a one-month-old Holstein-Friesian calf.