Fig. 7. Micrographs of cross sections of the red stripe zone. (A–C) White spider. (A) Unstained section. The red zone (left) and the white zone (right) of the epidermis. Two types of granules in the red zone are shown: the basal red type III (ommochromes) (asterisk) and type I granules (short, thick arrow) in the apical region of the cell. Only type I granules (long, thin arrow) are present in the white zone (bar, 20 µm). (B) Section of the red stripe zone showing fluorescent type I granules (arrow) in the apical and medial region of the epidermis. Note the absence of fluorescence from nuclei and the type III granules (basal region of the epidermis) (bar, 20 µm). (C) Electron micrograph of the red stripe showing a detail of the distribution of the type I and type III granules (bar, 2 µm). (D,E,F) Yellow spider. (D) The red zone (left; arrow) and the yellow zone (right) of the epidermis. Only type III granules (red and yellow) were observed in the red zone (bar, 20 µm). (E) Same region as in D, observed under UV light. Only the type II granules of the yellow zone show autofluorescence (arrow, half right of the picture) (bar, 20 µm). (F) Electron micrograph showing a detail of the same region as D and E. The dotted line delimits the red stripe and yellow regions (bar, 2 µm). C, cuticle; Gr I, granule type I; Gr III, granule type III.