ISSN:
1432-234X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary The ocellus of a synaptid holothurian,Opheodesoma spectabilis, is composed of sensory and supportive cells and underlain by numerous bundles of tentacular nerve fibers. Pigment cells in the tentacular nerve envelope the ocellus. A sensory cell is divided into three parts: an apical part from which a single cilicum and numerous microvilli arise, a slender middle part, and an enlarged basal part that contains an oval nucleus and gives rise to an axon. The axonemes in the cilia show varying degrees of remodelling. The following changes result from exposure to light: the microvilli become shorter and irregularly arranged; plasmalemmal invaginations engulf the microvilli; coated vesicles of varying appearances and membranous fragments become abundant; microtubules are less evident in the apical part; and small flat vesicles appear along the plasma membrane in the middle part. The evolution of photosensory cells and membrane turnover are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00993740
