Fig. 1

Transverse section of Trophon geversianus ovary in paraplast sections, stained with Sudan black B. a The area occupied by a vitellogenic oocyte (O) and its nucleus (N) is delimited, resulting in the cytoplasm area (C). b The software identifies every blue pixel within the cytoplasm. The area occupied by lipids (L) is the sum of the blue pixels. Scale bar 50 μm (color figure online)