principal act主要行为principaladj.主要的；首要的n.本金；资本；校长；主角；委托人；主犯principal decision- making校长决策principal picture components图像主要分量principal resonant frequency主要谐振频率principal distance of camera摄影机主距principal functional regions主体功能区principal way of doing st.主要做法Principal of cost accounting成本核算原则principal direction of glide脂移方向principal- agent mechanism委托-代理机制principal resonance response主共振响应

1. Tight junctions between adjacent principal cells permit the formation of a specific microenvironment in the lumen of the epididymis that is essential for sperm maturation.
   主细胞之间的紧密连接将附睾管腔形成一个特殊的微环境以促进精子成熟。