Figure 6

Stress concentration near two merged pools of cells undergoing apoptosis and replacement with GAGs. (a) Two collections of cells belonging to neighboring intra-lamellar regions are replaced by GAGs. The elastic lamella separating the two pools was removed prior to the study and the angular extent of the pools was assumed to be twice that of the single pool studied in Fig. 4 (1* = 4°, 2* = 8°, 3* = 16°, 4* = 40°). Shown are changes in circumferential stress of the (b) nearest elastic lamella and (c) intra-lamella space, as well as the second nearest (d) intra-lamellar space and (e) elastic lamella. Horizontal dashed lines show the baseline stress before introducing the pools. The model predicts that stress concentrations caused by two merged pools are in general higher than for a single-pool situation, especially at higher pressures. Rupture of the nearest elastic lamellae allows the elevated stress to reach the nearest and second nearest intra-lamellar cells (c and d), and to increase the chance of SMC damage. Meanwhile, the stress in the second nearest elastic lamellae also experiences a jump (e, step IV: lamellar disruption), more than the case with a single pool (Fig. 4e), thus predicting facilitated lamellar disruption and propagation of damage into the wall.