secondary ossification center

例句：

1. 1. The growth of the bone is a complex process involving multiple stages.
   骨骼的生长是一个复杂的过程，涉及多个阶段。
2. 2.The secondary ossification center is where the bone begins to harden and form.
   次级骨化中心是骨骼开始硬化并形成的地方。
3. 3. During puberty, the secondary ossification center undergoes significant changes in size and shape.
   青春期期间，次级骨化中心的大小和形状会发生显著变化。