We generated an oocyte specific deletion using Zp3 cre to study our gene of interest in mouse oocyte development. But, the heterozygous mice (+/- genotype in their oocyte) consistently give lower numbers of oocytes than the homozygous KO (-/- genotype in their oocyte) mice. The homozygous KO mice almost give similar number of oocytes as the control. Is it possible that sometimes the heterozygous deletion displays a more effective phenotype than a homozygous deletion?