The true internal kidney, mesenchyme, and various muscles, including the retractor muscles, arc derived from other progeny of the 3ML and 3MR teloblast
That might have accelerated the formation of teloblasts
from which adult structures are formed.
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).