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Fig. 2. Ommatidia, filtering pigment distribution and pattern of opsin gene
expression in lycaenid butterflies. (A) Longitudinal (left) and tangential
views (right) of the two types of ommatidia in the ventral eye of P.
icarus, non-pigmented (I) and red-pigmented (II). Purple pupillary
pigments are also present distally all in R1–8 photoreceptor cells
regulating the amount of light entering each ommatidium. c, cornea; cc,
crystalline cone; 9, the ninth photoreceptor; tp, tapetum; L, lamina; M,
medulla. (B) Red-filtering pigment in the lateral eye of P. icarus is
present in some ommatidia (a) and absent in others (b). (C) Cartoon of the six
ommatidial subtypes found in the ventral retina of L. rubidus with
respect to the non-overlapping expression of UVRh (UV, gray),
BRh1 (B1, dark blue) and BRh2 (B2, light blue) mRNAs in R1
and R2 photoreceptor cells. The LWRh mRNA (orange) is expressed in
the R3–8 cells. Note: the red-filtering pigment (red dots) of L
rubidus is coordinately expressed in the same ommatidia as those
expressing BRh2. Experimental data upon which the cartoon is based
are from Sison-Mangus et al. (Sison-Mangus
et al., 2006).