The circulatory system in the blastozooid
of the colonial ascidian Botryllus schlosseri (Pallas).
Each blastozooid can propagate both sexually and asexually.
Both processes may also operate in Botryllus schlosseri, where the origin of budding and organogenesis in the new blastozooid derives from a specialized region of the atrial epithelium that appears as a thickened button-like area (Manni et al, 2007; Fig.
Unmanipulated clutches were monitored for fusion or rejection over the oozooid stage (less than 7 days old) and in the week after takeover by the first asexual generation (called a blastozooid
, herein referred to as a zooid) 8-15 days post-settlement.
Reproductive outcomes in these chimeras could be as simple as the direct gametic representation of the diverse blastozooid units in the chimera; or could be as complex as the outcomes of selective resorption or germ cell parasitism that generate skewing from that simple representation (Pancer et al.
Until the time of chimeric colony senescence and death, robust blastozooids from all partners appeared to coexist within a single fused colony (Fig.
After this, several warnings were received during March across the ISCh: March 20 at Maillen Island (600 thousand oozooids and 54 thousand blastozooids
This first generation of blastozooids
produces its own buds, which in turn mature in about a week and subsequently die after giving rise to an additional set of zooids.