Methods Immature rabbits (One month old ) were divided into control group (treated with intratracheal 0.2 ml/kg normal saline) and BLM group (treated with intratracheal 4u/kg BLM).

• 方法 1月龄幼兔分为2周对照组(8只)和BLM组(10只)； 4周对照组(6只)，BLM组(9只)。