The photoreceptor array of the dipteran retina

Abstract The regular facetted appearance of the dipteran compound eye conceals an equally regular array of photoreceptors and interneurons that constitutes one of the most thoroughly analysed visual systems in any animal. The functional organization of the photoreceptor array, particularly in the house fly, Musca domestica , is now appreciated in unparalleled detail. A ‘standard set' of five spectral classes of photoreceptors is distributed over most of the eye and is supplemented by two discrete functional eye regions. One of these regions appears specialized for the analysis of polarized light patterns in the sky, and the other—found only in males — is apparently devoted to the task of tracking females in flight.