In view of the limitations inherent to phenomenological approaches, the problem of the internal structure of defects in nematics is here afforded from a molecular viewpoint. By using an extension of the Maier-Saupe mean-field potential which accounts for distorted states of nematics, the general equation applicable inside a defect is obtained by self-consistency. The specific example of the hedgehog point defect is developed in detail. It is shown that the size of the defect core depends on the order parameter characterizing the undistorted nematic phase: the core size decreases when the order parameter increases.