Rhopalium


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Rho`pa´li`um


n.1.(Zool.) One of the marginal sensory bodies of medusæ belonging to the Discophora.
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rainensis, the former based mainly on medusa size, bell wart size, and an apparent reduced number of eyes per rhopalium (compared with other cubozoans).
For recordings from the "pacemaker region" of a rhopalium, the electrode was placed on the aboral surface of the rhopalium (side opposite the eyes; inset in Fig.
In probing a rhopalium with a fiber optic light guide while recording from the pacemaker region, the complex eyes were found to be the areas most sensitive to photic stimulation.
In the lappets of the arms, away from the rhopalium, the FMRF-IR network was more random in neurite orientation relative to the strict radial orientation of tubulin-IR neurites (Fig.
First, in the region adjacent to a rhopalium, the neurites had a preferred orientation leading from the rhopalium (Fig.
FMRFamide immunoreactivity in the rhopalium was localized to a small network of cells surrounding the attachment site of the rhopalial stalk, as previously described (Martin, 2004; Skogh et ah, 2006; Parkefelt and Ekstrom, 2009).
In the region of the rhopalium, some neurons turned radially to extend into a compressed network within the smooth muscle band.
Each rhopalium had six eyes: one lower lens eye with a maximum diameter of 230 [micro]m, one upper lens eye with a maximum diameter of 150 [micro]m, a pair of pit eyes with a diameter of 20-30 [micro]m, and a pair of slit eyes with a length of 50-70 [micro]m (Fig.
Each rhopalium contains a statolith and six eyes: two camera-type lensed eyes (with cornea, retina, and lens), and four simple eyes (two slit-shaped ocelli and two pit-shaped ocelli) (Berger, 1898; Conant, 1898).
At each of the four perradii, a rhopalium hangs in an exumbrellar concavity (niche), a short distance up from the margin.
With 8 marginal arms, each with a terminal rhopalium flanked by 2 lappets.