Fine structure of complex ocelli of a cubomedusan, Tamoya bursaria Haeckel.

The retina of the distal and proximal lens-bearing complex ocelli are composed of pigmented sensory cells and long pigmented cells. A ciliary sheath from each sensory cell, together with the processes of long pigmented cells, extends through the vitreous layer as far as the capsule that envelops the lens. Each ciliary sheath has several ballon-like swellings and the ciliary microtubules, arranged in the 9+2 pattern in the proximal part, are markedly disorganized distally in the swollen parts, out of which extends most of the microvilli in the vitreous layer. It is suggested that some of the microvilli may originate in vesicles that are constricted off from the surface of the pigmented sensory cells. Closely packed microvilli run in parallel in short bundles. In addition to characteristic junctions between sensory cells, junctions that are presumably synaptic and, of a new type in coelenterates, are observed between sensory cells and nerve endings.