a$)$ Explain the zonal structures of cartilage tissue? Draw schematic diagrams What are the differences in between the zonal layers? Type at least $3$ of them. $(5$pts$).$

b$)$ Explain two of the currently in use cartilage tissue regeneration application. $(5$pts$)$

c$)$ Why cartilage tissue cannot be regenerated by itself? $(5$pts$)$

d$)$ What are the fundamental requirements of cartilage engineering scaffolds? $(5$pts$)$