While the formulae are specific to uniform and isotropic systems, the theoretical foundations of these formulae are in principle valid also for non-uniform and anisotropic systems (assuming that electrons in the normal state form a Fermi liquid). The basic idea has always been that with the superconducting coherence length ξ0 in the conventional BCS superconductors being some 2-3 orders of magnitude greater than the interatomic distance, these superconductors can to a good approximation be assumed uniform. In other words, a paired state in a BCS superconducting state extending over many interatomic distances, it experiences an almost uniform background. This cannot be said insofar as the high-Tc superconductors are concerned, since in these the Tc  is generally by some 2 orders of magnitude greater than the Tc  in the conventional BCS superconductors, whereby the superconducting coherence lengths in the former superconductors are by the same proportion smaller than in the latter.

@Behanam Farid Sir.....Thank you.

You are welcome Utpal.