A marked historical change occurs at the epiphysis of the ribs of infected pigs. 病猪肋骨骨骺处出现明显的组织学病变。
With unceasing growth of hyperplasia and ossification of epiphysis cartilage, it makes bone to grow unceasingly, therefore it grows. 在生长发育期，骺软骨不断增生和骨化，使骨不断增长，于是个子长高了。
