Purple stained nuclei evident within native cartilage of H&E stained specimens (Fig. 4). Progressive loss of nuclei with increased exposure to detergent/enzymatic decellularization in protocol A with no nuclei visible after 35 days. Protocol B demonstrates that after 14 days of decellularization using trypsin for the first 7 cycles, adequate decellularization can be achieved. Figure 4 displays absence of nuclei after 14 days. In the absence of trypsin as in protocol A, 35 days were required to achieve a similar histological picture of decellularization.