[Stephen Tucker (OP)]

One of my cats recently had to some of his fur shaved off in order to have blood drawn accurately. As the patch grew back, I began to wonder... How does cat fur "know" when it is long enough to stop growing? And how does it "know" when to detach from the cat?

Genes, hormones, etc., I'm sure, but more detail would be wonderful.  Thanks!

[RD]

answer to similar question here ... http://www.thenakedscientists.com/forum/index.php?topic=6182.msg62397#msg62397