Grade IV: The malignant tissue has cells that look most abnormal and tend to grow quickly.
第四级：有恶性组织细胞看起来最不正常的，而且往往增长迅速。
2
Grade I: The tissue is benign.
级：组织是良性的。
3
Objective to investigate the expressions of matrix metalloproteinase 2 (MMP 2) and tissue inhibitor of metalloproteinase 2 (TIMP 2) in astrocytoma and their relations to the pathological grade.