Genetic variation is stored in a populationâs gene poolâthe combined. alleles of all of the individuals in a population. Different combinations of. alleles in a gene pool can be formed when organisms mate and have offspring. Each allele exists at a certain rate, or frequency.
Also found in: Wikipedia. cosÂ·tal surÂ·face. the surface of certain structures that face the ribs; they are the costal surfaces of the lungs (facies costalis pulmonis [TA]) and the scapula (facies costalis scapulae [TA]).
Apical surface: upper surface. Basal surface: inner surfface. -microvilli forms brush borders (inestine) -cilia (moves, lining of trachea) -noncellular basal lamina. (adhesive sheet of glycoproteins secreted by epithelial cells. -works as a filter to see what can diffuse from underlying connective tissue.