phenotype affects entity vulval development vulval development phenotype reproductive system development variant vulva development variant vulva development abnormal WBPhenotype:0000699 C_elegans_phenotype_ontology Variations in the progression of the egg-laying organ of female and hermaphrodite nematodes over time, from its formation to the mature structure compared to control. In nematodes, the vulva is formed from ventral epidermal cells during larval stages to give rise to a fully formed vulva in the adult.