The Drosophila larva shows a clear segmental
patterning. The subdivision of the fly embryo into segmental entities
is a stepwise process that takes place within the first three hours
To understand the genetic program that leads to the segmental subdivision
of the body, Christiane Nüsslein-Vollhard and Eric Wieschaus
carried out a large screen for mutants in which the patterning process
is impaired. The analysis of the mutants identified was the first
step towards a detailed understanding of the underlying genetic program
that leads to the formation of the larval metameric pattern.
Drosophila larva bears characteristic rows of denticles at
its ventral side. Segments in different parts of the body show characteristic
denticle patterning, and within each segment, single cell rows can
be identified through absence or presence, as well as characteristic
shape of the denticles. Nüsslein-Vollhard and Wieschaus interpreted
mutant phenotypes by analyzing these denticle patterns.