Vascular regeneration and angiogenic-like sprouting mechanism in a compound ascidian is similar to vertebrates
Article first published online: 1 SEP 2008
© 2008 The Author(s). Journal compilation © 2008 Wiley Periodicals, Inc.
Evolution & Development
Volume 10, Issue 5, pages 591–605, September/October 2008
How to Cite
Gasparini, F., Burighel, P., Manni, L. and Zaniolo, G. (2008), Vascular regeneration and angiogenic-like sprouting mechanism in a compound ascidian is similar to vertebrates. Evolution & Development, 10: 591–605. doi: 10.1111/j.1525-142X.2008.00274.x
- Issue published online: 1 SEP 2008
- Article first published online: 1 SEP 2008
SUMMARY Tunicates are useful models for comparing differing developmental processes such as embryogenesis, asexual reproduction, and regeneration, because they are the closest relatives to vertebrates and are the only chordates to reproduce both sexually and asexually. Among them, the ascidian Botryllus schlosseri displays high regenerative potential of the colonial circulatory system (CCS). The CCS runs in the common tunic, forming an anastomized network of vessels defined by simple epithelia and connected to the open circulatory system of the zooids. During asexual propagation, new vessels form by means of a tubular-sprouting mechanism, resembling that occurring in other metazoans, particularly during vertebrate angiogenesis. We studied the regeneration of experimentally ablated CCS by analyzing the general dynamics of reorganization of vessels and tunic, their ultrastructure, cell proliferation, and the immunohistology of regenerating structures using antibodies against vertebrate angiogenic factors-vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), epidermal growth factor (EGF), and receptors: VEGFR-1, VEGFR-2, and EGFR. Results show that the regenerative process of CCS occurs by a sprouting mechanism, with participation of angiogenic factors. They also show correspondence between the CCS sprouting of B. schlosseri and angiogenic sprouting in vertebrates, during both normal development and regeneration, and support the idea that this morphogenetic mechanism was co-opted during the evolution of various developmental processes in different taxa.