We report here photoluminescence studies of multilayer InAs quantum dot structures grown by MOVPE on (001)-oriented GaAs substrates. AFM measurements reveal prolate shapes of the dots, oriented along the [1-10] direction. Different orientations relative to the interfaces between the GaAs matrix and InAs dots are probed using polarized excitation and detection. We suggest a possible role of local fields in models of the matrix-dot mixtures in the in-plane anisotropic response.