Regeneration in the Hemichordate Ptychodera flava

Humphreys Tom

Sasaki Akane

Uenishi Gene

Taparra Kekoa

Arimoto Asuka

Tagawa Kuni

Zoological Science

When the body of P. flava is severed, the animal has the ability to regenerate its missing anterior or posterior as appropriate. We have focused on anterior regeneration when the head and branchial regions are severed from the body of the worm. After transection, the body wall contracts and heals closed in 2 to 3 days. By the third day a small blastema is evident at the point of closure. The blastema grows rapidly and begins the process of differentiating into a head with a proboscis and collar. At 5 days the blastema has increased greatly in size and differentiated into a central bulb, the forming proboscis, and two lateral crescents, the forming collar. Between 5 and 7 days a mouth opens ventral to the differentiating blastema. Over the next few days the lateral crescents extend to encircle the proboscis and mouth, making a fully formed collar. By 10 to 12 days a new head, sized to fit the worm's body, has grown attached to the severed site. At about this time the animal regains apparently normal burrowing behavior. After the head is formed, a second blastema-like area appears between the new head and the old body and a new branchial region is inserted by regeneration from this blastema over the next 2 to 3 weeks. The regenerating tissues are unpigmented and whitish such that in-situ hybridization can be used to study the expression of genes during the formation of new tissues.

animal model

brain evolution

SEM

gill

in-situ hybridization

regeneration

acorn worm

Zoology [ 480 ]

eng

Zoological Society of Japan

日本動物学会

Copyright (c) 2010 Zoological Society of Japan

[NCID] AA10545874

[ISSN] 0289-0003

[DOI] 10.2108/zsj.27.91

[DOI] http://dx.doi.org/10.2108/zsj.27.91