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Figure 15
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The blastogenic cycle, the process of bud
formation resulting in the resorption of the adult zooid, of a botryllid ascidian is described. At any one stage, three generations
are usually observed (Berrill, 1947). The adult zooid produces a bud from its
body wall. The primary bud also produces a budlet which becomes a primary bud
once the adult zooid is resorbed (Berrill, 1947). A single cycle lasts approximately
seven days and the complete lifespan of an individual zooid is about three
weeks (Berrill, 1947). Abbreviations: branchial sac (bs), epidermis (ep), heart
(ht), peribranchial epithelium and stomach (st). Diagram adapted from Okuyama &
Saito, 2001.
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Figure 15
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