Longitudinal section of the pecten oculi of a pigeon (HE): folds (1)
The pecten consists of multiple folds or pleats that are apically held together by a â€˜bridgeâ€™. The folds attach basally at intervals along the whole border of the optic disc. The number of the folds varies amongst different bird species. Generally , diurnal birds have a bigger pecten with more pleats than nocturnal birds. The domestic fowl is described to have 16-18 pleats, pigeons 13-14, whereas owls only 5-10.