Characterization of the regeneration of the arm of the echinoderm Ophiothrix lineata (Lyman, 1860)

Abstract

Body regeneration is a common ability in most protostomate species, opposite to the lack
of such ability in deuterostomates. Regeneration in Echinodermata species is important to
understand regeneration in some exceptional chordate species. Echinodermata species have
a great ability to regenerate anatomical structures from their three germinal layers. In present
study, an arm was cut at its insertion in disc, at the first vertebra in Ophiotrix lineata, which
is a deuterostomate eccinoderm in search for its regeneration ability by recording periodical
stages in such a potential ability, since the very starting of a bud until the whole functional

differentiation. Records were taken every five days during a one-month span. Histological ex-
aminations were performed through the first eight days after amputation. Results demonstrated

a growth of 0.23 mm per day. Regeneration process was observed in four stages as follows:
first, re-epithelization of hurt disc, second, the formation of a regenerative blastema, third,
lengthening and segmentation of blastema, and fourth, cellular differentiation and mechanical
function of regenerated arm. It is remarkable the rapid formation of blastema as well as the
presence of radial nerve at sixth day after amputation.