I believe Tolkien said that Orcs reproduced 'in the way of the children of Iluvatar', that is, I assume, by giving birth. Fully-formed Uruk Hai emerging from slime was the creation of Peter Jackson, not Tolkien.
Mind you, I don't really blame anyone for not wanting to think about this in too much detail. Orc sex, orc babies - ew!
__________________
Out went the candle, and we were left darkling
|