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International Journal of Marine Science 2013, Vol.3, No.37, 295-305
http://ijms.sophiapublisher.com
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due to the multiple interventions of the spongin fibers
in regular as well as irregular fashion. Among the four
sponges, the skeletal arrangement was almost similar
for
F. cavernosa
and
H. cribriformis
, whose skeletal
network was formed to be branched in multiple
directions. The terminal portion of the spongin fiber in
F. cavernosa
(Inset) is highlighted to expose the bunch
of oxeae and collagen packed by an outer cuticular
layer. The junctional region of the spongin network in
H. cribriformis
(Inset) is covered with a membrane
like material. Ramifying spongin fibers were seen in
C.
fibrosa
, where native spongin network was observed
to be thicker and internal striations of the spongin
were clearly visible at high magnification (Inset). The
spongin network observed in
D. fragilis
was unique in
possessing multiple types of fibres loaded with sand
grains, broken spicules and other foreign material
covered by a very thin transparent layer of amorphous
material, softly holding the bunch of parallely
arranged detritus material (Inset) with the support of
tiny collagenous material.
Scanning electron microscopy
Ultrastructural orientation of the differential skeletal
make up and varied distribution of spongin in extra
cellular matrix of four experimental marine sponges
was analyzed by Scanning Electron Microscopy (SEM)
(Figure 3-6). SEM analyses depict the branching and
pattern of spongin network and the lattice distribution
of silicon layers cemented around the interlacing
skeletal fibers. At higher magnifications,
C. fibrosa
exhibited a distinct skeleton formed of thick walls of
silicon based sheets layered along with the spongin
and uniform sized spicules (Figure 3). The peeled off,
fragmented material at the broken portions of the
tissue seem to appear as collagenous layers packed at
different densities. On the other hand, SEM analysis
of
D. fragilis
depicted
a number of spacious cavities
called atria, formed of bundles of different variety of
material composed of detritus and fragmented spicules
intercalated with amorphous siliceous material rather
than much fibrous protein (Figure 4).
It is clearly observed from the SEM results that
carpets of amorphous material are seen much in the
case of
F. cavernosa
(Figure 5)
.
The skeleton found to
be majorly formed of large spongin fibers supported
Figure 3 Scanning electron micrographs of
Callyspongia
fibrosa
showing the much interlacing skeletal network.
A)
Disrupted spongin network exposing the collagenous form of
terminal portions and B) Enlarged view of spongin network
showing peeled off amorphous layer
Figure 4 Scanning electron micrographs of
Dysidea fragilis.
A)
Enlarged view of skeletal branches formed by high density of
detritus material; B) Enlarged view of a branch of skeleton
formed of diversified spiraster like material and C) Image
showing a variety of large spiraster
by the proteinaceous sheets of extracellular material,
mainly impregnated with spicule like fragments
intercalated with collagen fibrils passing through the
sponge atria. Although the cellular (pinacocytes and
choanocytes) appearance in the experimental sponge
sections was not remarkable because of the processing