Ultrastructural organization of choanocyte chambers in the haploscleridPellina semitubulosa(Porifera, Demospongiae): A cue for water flow into the sponge body

Abstract

Citing articles: 1 View citing articles Ital. J. Zool., 64: 291-296 (1997) ABSTRACTThe choanocyte chambers of the haplosclerid Pellina semitubulosa were investigated with regard to their ultrastructural architecture. They are separated from the mesohyl and contain central cells arranged to form a uniform layer. Their cytoplasmic extensions enter the distal parts of the choanocyte collars, thus enveloping the end of the microvilli. Central cells seal up all the spaces between choanocyte collars. On the basis of choanocyte chamber architecture, a water flow dynamics and related filter feeding activity is proposed, which supports a water passageway through the small microvillar slits into the interior of the collar. A slight detachment of the central cells from the microvillar ends originates spaces for a direct water flow into the chamber. Such a plastic organization might enhance the filtration efficiency and prevent chamber clogging as well.

Some steps of spermatogenesis inHalichondria semitubulosa(Demospongiae, Halichondriidae)

“…The specimens are small in size and may grow as epibionts on algal thalli. This species has been the subject of previous investigations focused on the architecture of the aquiferous system (Sciscioli et al 1997), and on the silica content and spicule size variations (Mercurio et al 2000). In the former paper, based on the fine organization of the choanocyte chambers, the water flow dynamics and related filter-feeding activity were described.…”