The identification and mapping of spectral cell types in the retina of Periplaneta americana

Selective adaptation and subsequent histological examination reveal two receptor types in Periplaneta in the ratio 3 (UV)∶5 (green). This is supported by statistical analysis of 25 ommatidia for each treatment.Both receptor types occur in the same ommatidium (Fig. 1).The position of each receptor type is fixed within ommatidia, the pattern being repeated across the entire retina (Figs. 1, 3, 4).Mirror-images of receptor patterns occur only between the two compound eyes about a dorsal-ventral axis (Fig. 1).No inter-retinal transfer of adaptation effects exists.The extent of the palisade and rate of pigment migration is very localized within individual cells and is related to the amount of rhabdomere immediately present.