Reiswig, H.M.; Mehl, D. (1991). Tissue organization of Farrea occa (Porifera, Hexactinellida). Zoomorphology. 110: 301-311.
Reiswig, H.M.; Mehl, D.
Tissue organization of <i>Farrea occa</i> (Porifera, Hexactinellida).
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The tissue organization of Farrea occa has been examind by light microscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). It was found to agree closely with the hexactinellid model established for Rhabdocalyptus dawsoni by Mackie and Singla (1983) in consisting of a thin general syncytium incorporating few discrete cellular components, several of which share membrane continuity with the general syncytium by distinctive plug junctions. The general syncytium, supported by a thin collagenous mesolamella, is specialized regionally as dermal membrane, gastral membrane, peripheral trabecular strands, and primary reticulum (R1) of flagellated chambers. Extensions of the syncytium, which lack mesolamella support, form the distinctive secondary reticulum (R2) inside chambers and a newly discovered structure, the "inner membrane", which occupies the central region of flagellated chambers. The choanosyncytia are enucleate networks
of collar bodies and stolons embedded in R1 and plugged to R1 and choanoblasts. The discrete cell population consists of choanoblasts and archeocytes located in the thin mesohyle space and plugged to syncytial elements, cystencytes and vacuolar cells also located in the mesohyle but lacking plug connections, and granular cells emergent on R1 and apparently not bearing plug connections. The status of scleroblast syncytia has not
been resolved. Large populations of rod-shaped bacteria occupy the mesohyle space; intracellular ovoid bodies, possible symbiotic prokaryotes, are common in R1 and R2. The previously unknown inner membrane probably functions to control flagellar activity on a very localized scale and to accumulate and release egesta in packages.