Human population can be classified into secretors and non-secretors. These are categorized on the basis of presence or absence of the blood group antigens (A, B and H) in the body fluids and secretions, such as saliva, perspiration, tears, semen, serum, mucus present in the digestive tract or respiratory cavities etc. Secretors are individuals that secrete bloodstream group antigens in their body fluids while non-secretors are the people that do not secrete them in their..
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