Microgrid concept provides an appropriate context for installing distributed generation resources and providing reliability and power quality for sensitive loads. Most of the literature have analyzed the effects of different power control strategies of inverter-based distributed energy resources on the stability of microgrids and only a few of them have addressed various load models in their formulation and analysis. This paper proposes a well-structured formulation for state-space representation of comprehensive static and dynamic load models in an islanded microgrids environment. Impact of considering induction motor models on root loci of eigenvalues is analyzed and sensitivity calculation is performed to account for the effect of different load model parameters on system oscillatory modes.