Single cancellous osteomas, unlike exostosis, are a relatively rare lesion in the external auditory canal.

单性疏松瘤，不像外生，个外耳道较见的病灶。

Blood production —The marrow, located within the medullary cavity of long bones and the interstices of cancellous bone, produces blood cells in a process called haematopoiesis.

造-位于长腔和松质间隙内，通过造作用产生细胞。