Selective habitation of bacteria on "intermediate soft" keratin surfaces of the rat tongue.

Scanning and light microscopy reveals a selective and restrictive pattern of indigenous bacterial colonization on the tongue of rats which is accounted for by the preferred attachment of bacteria to an "intermediate soft" keratin substrate. Total intravenous feeding of rats for 10 days did not alter this colonization pattern indicating that oral intake of food is not responsible for maintenance of this pattern.