Strong allele.

Larvae show no proventricular defects.

Mutant embryos have a lawn of row-2, row-3, row-4, row-5 and row-6-type ventral denticles, with naked patches in alternate segments.

en⁵⁷ embryos had normal wg and arm protein distribution during midembryonic stages but changes were seen in protein accumulation at later stages.

en mutant embryos lack all Keilin's organs. en⁵⁹/en⁵⁷ embryos grew in in vivo culture, producing implants containing imaginal discs and all larval tissues. Metamorphosed implants were often characteristic of eye-antenna discs.

The odd⁵ phenotype is largely suppressed by en⁵⁷ in double homozygotes.

Some cells from the embryonic central nervous system are missing in the thoracic region in homozygotes.

en⁵⁷/en¹ flies have wild-type shape wings and a wild-type scutellum. Vein III appears thickened and tends to have a posteriorwards bulge about halfway along its length. The anterior crossvein (ACV) is often reduced or absent. Small plexae of vein tissue tend to occur close to the ACV and the posterior crossvein. Vein IV is frequently interrupted and often carries campaniform sensilla. Bristles are occasionally seen in the posterior row, but they never have the characteristics of the middle triple row.

Homozygous en⁵⁷ cells in mosaic animals made by nuclear transplantation do not develop normally in posterior parts of the epidermis and some regions of the CNS, but form normal patterns in mesodermal and endodermal organs.

Posterior homozygous clones in the proboscis are often associated with abnormal bristle patterns. Clones in the posterior part of the wing are abnormal: the wing is enlarged and the posterior margin has large socketed bristles and a well-developed triple row in the clone. Posterior clones do not respect the anteroposterior compartment boundary in the wing. Posterior clones in the leg are often grossly enlarged with a huge increase in the number of bristles. In the male, clones in the genitalia are often associated with missing parts of the claspers, lateral plate and hypandrium, and clones in the analia form unusually shaped anal plates and are often associated with missing genital parts.