Proteome maps obtained by synchronization of the wild-type Caenorhabditis elegans development reflected stage-dependent molecular differences and revealed dynamic cytoskeletal processes during ontogenesis. Distinct protein spots that may function as molecular markers for the corresponding developmental stages were mass spectrometrically identified. The amount of the Cu(2+)- Zn(2+) superoxide dismutase (CE23550) and an aspartyl proteinase (CE21681) was highest in the first larval stage (L1) and decreased during the ontogenesis from the first larval stage to the adult. Tropomyosin III (CE29059) was prominently present in the first and second larval stage (L1/L2). Abundances of actin 1 or 4 (CE12358 or CE13148) and tropomyosin I (CE28782) were particularly high in multiple spots in the third larval stage (L3). Interestingly, the amount of DIM-1 protein (CE27706), reflected by two spots, was the lowest in this stage. A particular splicing factor (CE31089) was detected only in the fourth larval stage (L4), whereas a spot with high abundance representing the cuticle collagen (CE02272) was only found highly expressed in adult animals (A). In addition, a Ca(2+)-binding protein (CE12368) and one protein spot which has not yet been identified, both reached their maximal spot intensities in the adult stage (A). Moreover, the ASP-1, CCT-5, GPD-1, GPD-2, HSP-6, HSP-16.2, IFB-2, LEC-2, LIN-53, LMN-1, MDH-1, NUD-1, RPA-0, RSP-12, SOD-1, TBB-1, TBB-2, TMY-1, UNC-60, and VIT-2 proteins for which mutants are available and two still unidentified protein spots which were present in all developmental stages, have been reproducibly localized in proteome maps of distinct ontogenesis states.