engrailed (en) is a segmentation gene expressed in a series of stripes throughout embryonic development. Here, I show that regulatory sequences for striped expression are present within the first intron of en. The 1-kb intron is able to confer striped expression early, but not late, in development.

ventral ganglion
In the ventral ganglion engrailed appears to be expressed by a subset of cells, primarily in the posterior regions of each segment. In wing discs from animals that are homozygous for the en1 mutation, the pattern of expression of the gene is altered, as opposed to being simply reduced uniformly in the posterior cells.

engrailed is first expressed in early gastrulating embryos, three to four hours after fertilization. The first stripe is just posterior to the deep groove subdividing the head (cephalic furrow). Subsequently, 13 other stripes appear along the longitudinal axis of the embryo.

wingless, a member of the Wnt gene family, is an essential gene for segmentation in Drosophila, and is also involved in many other patterning events. The gene encodes a secreted protein that can regulate gene expression in adjacent cells.

Its earliest identifiable role during development of Drosophila is in the embryonic segmentation cascade, wherein wingless functions as a segment polarity gene and serves to pattern each individual segment along the antero-posterior axis of the developing embryo.

Engrailed (En) is a member of the homeobox gene family, which encodes a homeodomain-containing transcription factor that is essential during early development.

In Drosophila, the “engrailed” (en) gene plays an important role, determining segmentation during development and is required for the formation of posterior compartments.

: having no wings or very rudimentary wings.

The critical roles of Wingless during adult intestinal development, which include regulation of target gene activation, boundary formation, stem cell proliferation, epithelial cell fate specification, muscle differentiation, gut folding, and signaling crosstalk with the Decapentaplegic pathway, are all were disrupted …

In characteristic style Nature, Cell and Science broadcasted the news: Wingless was –and by the way still is- a Morphogen. Particularly during a crucial phase in the growth of the wing disc, all cells appears to express low levels of wingless.

The engrailed gene is thought to be a ‘selector’ gene that controls the expression of other genes to confer a ‘posterior identity’ on groups of cells that are related to each other by lineage.

The engrailed gene is thought to be a ‘selector’ gene that controls the expression of other genes to confer a ‘posterior identity’ on groups of cells that are related to each other by lineage. It has a late role in patterning the wing margin, which includes cells within the anterior compartment.