  By using a Path Integral formalism, we study the fluctuating fields in the
order parameter for a 3D uniform Fermi gas at T<Tc. The BCS-BEC crossover
condition is included into the analysis in the framework of the usual s-wave
scattering approximation. The general expressions for the temperature
dependence of the partition function and the quadratic average in the
fluctuations fields are explicitly established in terms of the BCS-Gor'kov
correlation propagators.
