Greatly reduced anterior structures and expanded gnathal and thoracic structures.

Eggs derived from homozygous females cellularise normally but become abnormal at gastrulation; the cephalic furrow is shifted forward and the anterior most cells form an inverted posterior end, forming a posterior midgut, proctodeal region and often Malpighian tubules. Anterior head structures of the cuticle are missing.

The thoracic and segmented head anlagen is enlarged while the posterior pattern is compressed. Low levels of bcd protein are distributed in a shallow gradient throughout the embryo.

Embryos derived from bcd⁶/bcd⁷ females show some development of at least thoracic and frequently head structures when injected at the anterior tip with cytoplasm taken from the anterior tip of wild-type embryos. In contrast, cytoplasm taken from the anterior tip of embryos derived from exu¹/exu² females shows barely detectable rescuing activity when injected into the anterior tip of embryos derived from bcd⁶/bcd⁷ females. The phenotype of embryos derived from exu¹/exu² females is more or less unmodified if cytoplasm is removed from the anterior tip of the embryo.