Posterior segmentation of the Drosophila embryo in the absence of a maternal posterior organizer gene.

Maternal hunchback activity suppresses the genetic pathway for abdomen formation in the Drosophila embryo. The active component of the posterior group of maternal genes, nanos, acts as a specific repressor of hunchback in the posterior region. Absence of both repressors results in normal embryos, indicating that posterior segmentation may not directly require maternal determinants.