Blood Types and the Population. O positive is the most common blood type. Not all ethnic groups have the same mix of these blood types. Hispanic people, for example, have a relatively high number of Oâs, while Asian people have a relatively high number of Bâs.The mix of the different blood types in the U.S. population is:n addition to the A and B antigens, there is a third antigen called the Rh factor, which can be either present (+) or absent (â). In general, Rh negative blood is given to Rh-negative patients, and Rh positive blood or Rh negative blood may be given to Rh positive patients.
Medical Definition of LENTIGO. 1. : a small melanotic spot in the skin in which the formation of pigment is unrelated to exposure to sunlight and which is potentially malignant; especially: nevusâcompare freckle. 2. : freckle.
Updated November 24, 2014. Definition: Dentin is a tissue that is calcified and consists of tiny tubules or tubes. It is the second layer of the tooth and is normally covered by enamel and covers the pulp, making up the majority of the tooth's structure. Both denser and harder than bone, the color of dentin may range anywhere from grey to black but is typically a pale yellow.