MIGRATION AND PROLIFERATION OF PROGENITOR CELLS IN THE CONNECTIVE-TISSUE OF RAT GINGIVAL PAPILLA

The aim of this investigation was to determine whether gingival fibrob last progenitor cells undergo division and whether there is evidence o f migration of their progeny from the paravascular sites within the in terdental gingival septum (IGS). 30 male hooded Lister rats aged 6 wee ks, were killed in groups of ten, 3, 75 and 171 h after a single injec tion of tritiated thymidine, Autoradiographs were examined of transver se Historesin sections of the papilla between second and third mandibu lar molars in 29 specimens, taken from equidistant intervals between t he col and alveolar bone crest. Median grain counts in the whole papil la were greatest within 10 mu m of blood vessels at 3 h (p < 0.02) and decreased throughout the papilla with time (p < 0.0001). The median g rain counts at level 5, nearest the periodontal ligament, were greates t at all times (p < 0.01). The distance of labelled nuclei from blood vessel walls increased with time, most notably at level 5 (p < 0.001). The mean Clustering Index increased (p < 0.01) from 4.6% at 3 h to 12 .3% and 11.6% at 75 h and 171 h respectively. At 75 h, the median grai n count of clustered nuclei was smaller (p < 0.01) than that of nonclu stered nuclei. These data are consistent with the occurrence of clonal division and migration within the IGS and the presence of a slowly cy cling cell population near to the periodontal ligament.