1. Ectochondral ossification refers to the process by which bone develops directly from cartilage.（外骨发育是指骨骺从软骨直接发育的过程。）
2. Ectochondral bone growth is a critical step in the formation of the skeleton during embryonic development.（外骨骺生长是胚胎发育过程中骨骼形成的关键步骤。）