Normal fetal brain at 22 weeks gestation (unlabelled - see labelled images below). Note the five layered laminar appearance, appropriate for this stage of gestation. The Sylvian fissures are becoming squared, but still open. The parieto-occipital fissures are present, and the calcarine fissures are becoming visible. The cingulate sulcus is not yet visible. The brain surface is generally smooth, with no secondary or tertiary sulci present.