. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 528 DANIEL L. ALKON. FIGURE 20. Formaldehyde-induced fluorescence in the optic ganglion (OG). A: phase contrast optics showing the ganglion and individual axons within the optic nerve (ON). B: fluorescence microscopy of the above. One cell within the optic ganglion has intense greenish fluorescence indicative of catecholamines. Note that the fluorescent material is concentrated in the cytoplasm and in the axon, but not in the nucleus (Heldman ct al., 1979). front of the force vector experience the weight of the statoconia (a
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 528 DANIEL L. ALKON. FIGURE 20. Formaldehyde-induced fluorescence in the optic ganglion (OG). A: phase contrast optics showing the ganglion and individual axons within the optic nerve (ON). B: fluorescence microscopy of the above. One cell within the optic ganglion has intense greenish fluorescence indicative of catecholamines. Note that the fluorescent material is concentrated in the cytoplasm and in the axon, but not in the nucleus (Heldman ct al., 1979). front of the force vector experience the weight of the statoconia (as accelerated by rotation) and move with a fundamental frequency of 7 Hz. Hair cells located on the statocyst so as to be behind the force vector hyperpolarize, show a decreased voltage noise, and decrease firing in response to rotation. The hairs of these cells behind the force vector do not interact with the statoconia, which have been moved (as accelerated by rotation) to the opposite half of the statocyst (Fig. 22). These hairs move with a fundamental frequency of 10 Hz. These observations and a number of additional experiments involving alteration of hair movement (with such treatments as cooling, hypertonicity, chloral hydrate, vanadate, and 4,4'-dithiobisphenyl azide) indicate that the hair cell generator po- tentials arise from summation of increased voltage noise (DeFelice and Alkon, 1977; Grossman et al., 1978; Stommel ct al., in press) which in turn arises from force exerted by the statoconia on the hairs but not from hair bending per sc. This force then causes sustained membrane distortion and consequent conductance changes at the base of the cilia (Fig. 23) rather than on the ciliary shafts. The hair cells in Hermissenda, unlike vertebrate hair cells, have axons which join together to form the static nerve, which extends for 30-40 //.m before entering the pleural ganglion. Cutting the nerve proximal to this point of entry can elimi- nate all spontaneous impulses an
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