Morphology of the medusa marginal tentacle in <i>Aurelia sp</i>.<i>1</i>.

<p>All scale bars equal 50 μm. (A) Illustration of a longitudinal section of the medusa marginal tentacle in <i>Aurelia</i>. (B) Phalloidin staining of three marginal tentacles (upper left proximal, lower right distal), which elucidate the muscle chord running down the oral side of each tentacle. A single tentacle has been digitally isolated using Adobe Photoshop in the upper-right box (left proximal, bottom oral) to clarify the distinction between the proximal “blade” (bl) and distal “constriction” (co). (C) Confocal longitudinal section of the marginal tentacle, showing where the proximal “blade” changes into the radially symmetrical distal “constriction”. (D) Another confocal longitudinal section, highlighting the dense packing of endodermal (en) cells in the distal portion of the tentacle. Note the distinction between this morphology and the chordal morphology seen in the polyp (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134741#pone.0134741.g002" target="_blank">Fig 2A and 2B</a>). (E) Z-projection illustrating the modular clusters of cells in the distal portion of the marginal tentacle. (F) A longitudinal section of Fig 3E. (G) A Z-projection of phalloidin staining in Fig 3E. Note in (F) and (G) that phalloidin bands do not appear to generate cohesive longitudinal musculature, but instead form localized musculature within each module (H) Low-magnification image of neural distribution across the medusa bell. Arrowheads indicate putative clusters of Ttub-positive neurites. (I) High magnification of the proximal-most end of the tentacle, showing FMRFamide and Ttub-positive neurites associated with the muscle chord. (J) A Z-projection revealing the high concentration of “capsule”-positive cnidocytes in the tentacle ectoderm. (K) A partially fired cnidocyte from 2J (white box), digitally isolated using Adobe Photoshop. (L) Longitudinal TEM section of a microbasic heterotrichous eurytele (X 9,000).