Quark mass matrices and observable quantities

A nearly historical account of quark mass matrix models is given, and the structure of quark mass matrices in the Standard Model is studied. For a minimal parameter basis suggested earlier, where $M_u$ is diagonal and $M_{d11}$, $M_{d13}$, $M_{d31}$ are zero, the dependence of mass matrices on the CP violating phase $\delta$ of $V_{CKM}$ is reported: all parameters are almost independent, except $M_{d22}$ and $M_{d23}$, and the equality $|M_{d22}|=M_{d23}$ is obtained for a value of $\delta$ very close to the value which is favoured by experiments. Moreover, on this basis, $M_{d12} \simeq M_{d21}$ and $M_{d33} \simeq 2M_{d32}$. Some comments on mass matrices in left-right symmetric models are added.