To solve the problem of determining the number of orbitals with electron density along the axis from the given set, we need to analyze each orbital type: $p_x$, $p_y$, $p_z$, $d_{xy}$, $d_{yz}$, $d_{xz}$, $d_{z^2}$, and $d_{x^2-y^2}$.
Considering the above analysis, the orbitals with electron density along the axis are $p_x$, $p_y$, $p_z$, $d_{z^2}$, and $d_{x^2-y^2}$. Hence, the total count is 5.
The total number of molecular orbitals formed from 2s and 2p atomic orbitals of a diatomic molecule is _________.