These movements result in the internalization of the naupliar mesoderm and endoderm and in the localization of teloblasts
in the most posterior part of the nauplius larva (Hertzler and Clark, 1992; Hertzler, 2002, 2005; Alwes and Scholtz, 2004; Biffis et al., 2009).
That might have accelerated the formation of teloblasts
from which adult structures are formed.
The progeny of 4d are named here using a new nomenclature modified after that of Conklin (1897), where the teloblasts
are designated with a capital letter, M, and the daughters with a lower case letter, m.
Expression of hunchback protein in a subset of ectodermal teloblasts
of the oligochaete annelid Tubifex.
Mesoderm formation in polychaetes is attributed to two teloblasts
, derivatives of the 4d blastomere, which reside between the posterior ectoderm and the lining of the developing gut (6).