Do you mean the whitish build up on some newborns' nipples? If so, that is a hormonal reaction that happens in the womb due to the mother's hormones...
In fact, some full term male infants have actually secreted their mother's milk through their nipples.
If you are asking a different question, try rephrasing, because I am not sure what you are asking either.
at 3:17 AM on Jul. 8, 2009