Figure 5: Proliferation in the embryonic chicken growth plate is disrupted by the removal of mechanical stimuli.

PCNA expression in (a) control and (b) immobilized distal femur at E14. The mean ± SEM % total cells which express PCNA in the 1) articular cartilage, 2) “resting zone” cartilage, 3) proliferative zone and 4) prehypertrophic/hypertrophic zone was quantified in (c) control and (d) immobilised (n = 5 for each group) limbs at E14, after 4 days of treatment. (e) Mean ± SEM % total cells in each zone. Phosphohistone H3 expression in the (f) control and (g) immobilized distal femur at E14. The mean ± SEM % total cells that are phosphohistone H3 positive was quantified from a representative view of the epiphysis of (h) control and (i) immobilized limbs at E14, after 4 days of treatment, and E18, after 8 days of treatment (n = 5 in each group). (j) Mean ± SEM % total cells phosphohistone H3 positive. BrdU incorporation in (k) control and (l) immobilized E16 chick limbs sacrificed 4 hours after BrdU administration, after 6 days of treatment. The mean ± SEM % total cells which are BrdU positive in the proliferative zone (shown by dotted lines) or the prehypertrophic/hypertrophic zones of (m) control and (n) immobilised limbs (n = 5 in each group; indicated by yellow squares) 4 hours after BrdU administration was quantified. (o) Mean ± SEM % total cells phosphohistone positive in these regions. Mean values from the two treatment groups were analysed by Mann-Whitney U test. *Indicates P < 0.05. Scale bars represent 200 μm.