Cell-cell recognition.
The earlier step of morphogenesis is the segregation of cell lines which are homogeneous cell populations each endowed with its own specific developmental program. In order for the program to unfold in each line cells must be endowed with specific surface properties whereby the cells belonging to the same line can recognize each other as such in addition to recognizing those belonging to other cell lines as different. Experiments supporting this view are described. The hypothesis is presented that the cell-cell recognition system is phylogenetically linked with the invention of sexuality.
D000818:Animals; D002449:Cell Aggregation; D002450:Cell Communication; D002454:Cell Differentiation; D002460:Cell Line; D003063:Cnidaria; D005854:Germ Cells / Q000502:physiology; D013499:Surface Properties