. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SENESCENCE IN A COLONIAL ASCIDIAN 371. Figure 2. Bnnyllus scli/osseri colonies at different stages of nonrandom senescence, (a) Appearance of star-shaped groups of zooids in a nonsenescent colony, (b) A representative colony 3 days following the onset of senescence. Note the dark pigmentation pattern within zooids and accumulation of pigment cells in blood vessels and ampullae, (c) At day 6 of nonrandom senescence, there is loss of colonial architecture. The zooids within individual systems have disconnected from one another
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SENESCENCE IN A COLONIAL ASCIDIAN 371. Figure 2. Bnnyllus scli/osseri colonies at different stages of nonrandom senescence, (a) Appearance of star-shaped groups of zooids in a nonsenescent colony, (b) A representative colony 3 days following the onset of senescence. Note the dark pigmentation pattern within zooids and accumulation of pigment cells in blood vessels and ampullae, (c) At day 6 of nonrandom senescence, there is loss of colonial architecture. The zooids within individual systems have disconnected from one another following loss of the common excurrent siphon. Note that the siphons from individual zooids have greatly dilated. Systemic blood flow has almost shut down except for the central part of the colony, (d) The end stage of senescence (day 7) is characterized by complete stasis of the colonial vasculature and dead zooids with closed siphons, (el A different colony at day 5 of nonrandom senescence, observed at 60 hours following the onset of takeover (bottom left corner). Note that the zooids of the previous asexual generation are still visible (black arrows).(f) The same colony observed at 110 hours following onset of takeover, depicting dead zooids with resorption products still visible (black arrows). Panels a-c and d represent dorsal and ventral views respectively of zooids from different portions of the same colony (orange color morph) undergoing nonrandom senescence. Panels e-f are dorsal views of the same part of a different colony (blue/brown color morph). The numbers at the bottom left portion of panels a-d represent the days following onset of nonrandom senescence. Abbreviations: am, ampulla; bv, blood vessels; es, excurrent siphon; os, oral siphon; t, tunic. Asterisks represent the region occupied by the common excurrent siphon. Scale bars equal 1 mm for panels a-d and e-f Please note that these images are extracted from scanned page images that may have be
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
