After this productive period, signals within the skin instruct some follicles to enter a new phase known as catagen, or the regressing stage, causing hair follicles to shrink to a fraction of their original length.

在这段高产时期之后，皮肤里的信号命令一些发囊进入一个新的阶段，这个阶段叫做毛发生长中期，或者倒退期，倒退期使发囊缩小至他们原来长度的一小段。