3 research outputs found
The embryoid development of Strigamia maritimaand its bearing on post-embryonic segmentation of geophilomorph centipedes
Trunk segment numbers and sequential segmentation in myriapods
Sequential segmentation from a posterior
\u2018\u2018proliferative zone\u2019\u2019 is considered to be the primitive
mechanism of segmentation in arthropods. Several studies
of embryonic and post-embryonic development and gene
expression suggest that this occurs in all major arthropod taxa.
Sequential segmentation is often associated with the idea
of posterior production of body units that accumulate along
the main body axis. However, the precise mechanism of
sequential segmentation has not been identified yet, and,
while searching for the genetic circuitry able to generate a
first periodic pattern in the embryo, we can at least outline
the distinctive role in segmentation of a proliferative zone.
A perusal of myriapod segmentation patterns suggests
that these patterns result from multi-layered developmental
processes, where gene expression and epigenetic
mechanisms interact in a nonstrictly hierarchical way. The
posterior zone is possibly a zone of periodic signal production,
but, in general, the resulting segmental pattern is not
completely attributable to the activity of the signal generator.
In this sense, a posterior proliferative zone would be more a
\u2018\u2018segmental organizer\u2019\u2019 than a \u2018\u2018segment generator.\u2019\u201