Representative pictures of primary porcine kidney epithelial cells (PKC) at different states of confluence. Pictures show PKC cultures of passage 0, 7 days after isolation with different confluence levels: A, post-confluent (>100% confluence); B, confluent (100% confluence); C, semi-confluent (~70% confluence); the used terms of confluence define the various density states of the cultures, i.e. non-confluent (described as <100% confluence), confluent (a state where the dish is completely covered with cells, described as 100% confluence) and post-confluent (a state, where the maximal cell number is reached, described as >100%). The latter does not mean that these cells grow in multilayers, but that they are able to close ranks more tightly before they stop proliferating due to contact inhibition.
Heussner and Dietrich BMC Cell Biology 2013 14:55 doi:10.1186/1471-2121-14-55