Fig. 8

Structural analysis of ovaries using immunohistochemistry and confocal laser-scanning microscopy. A Wild-type ovary (one half) with germarium (marked with ‘g’) at the tips of the ovarioles and growing oocytes. White arrowheads point to oocytes that reached a mature size. Lateral oviduct (red asterisk) is widened and presumably contains mature oocytes. B ‘Small-ovary’ phenotype from PC2 background: In this milder form of the phenotype the proportions of the ovarioles are maintained but the size of the most mature oocytes is reduced (white arrowheads) when compared to wild-type ovaries. Oviducts (red asterisks) do not contain mature eggs. C More severe ‘small-ovary’ (from PC1/3 background). Ovarioles remain slender due to the small oocytes, which show an irregular outline. Some oocytes are seen disintegrating (white arrows) and oviducts (asterisks) do not seem to contain mature eggs. Mild and severe ‘small ovary’ phenotypes were seen in both PC1/3 and PC2 knockdowns. D Ovary of an untreated beetle starved for 10 days after eclosion, showing a similar ‘small-ovary’ morphology. Oviducts (red asterisks) do not contain mature eggs. E–H Higher magnification captures of individual mature oocytes. E) Wild type: the oocyte membrane lines the follicle sheet without gaps. The white star marks the expected position of the nucleus which is not stained in the fully grown wild-type oocytes, probably due to insufficient penetration of the dye. F Oocyte from a mild ‘small-ovary’ phenotype. Similar to wild type, the egg is oval, and the cell membrane is lined by the follicle cell sheet without gaps. G High magnification of an oocyte from a severe ‘small ovary’ background: The oocyte is not oval and detached from the follicle sheet (red arrows). H An oocyte of a ‘starved’ background displays a similar gap between the egg membrane and the follicle sheet (red arrow). A–G are maximum intensity Z-projections (created with imageJ) and are based on multichannel confocal laser scanning image stacks with each channel using the same plane thickness to avoid optical shift