The distribution of two cell-adhesion molecules, E- and P-cadherin, was stu
died in relation to morphological changes in Hertwig's epithelial root shea
th. Before root dentinogenesis had started, the root sheath expressed both
cadherins. As dentinogenesis proceeded, the sheath fragmented and lost P-ca
dherin rapidly and E-cadherin slowly, whereas the intact sheath at the apic
al end continued to express both. These results suggest that the two cadher
ins play a part in root as well as in crown development, and indicate that
the decrease in the amount of these molecules and the fragmentation of the
epithelial root sheath are interrelated. (C) 1999 Elsevier Science Ltd. All
rights reserved.