10
IVAN UOODBODY
(c) Perophura viridh Vcrrill (Deck et al., 1966) (Fig. 5 ) . The test of
Perophora is much thinner m d more translucent than in Phallusia.
Filaments of about 80 A diameter lie in a homogeneousground substance ;
the structure of those lilanicnts in c.onHistent with their being a cellulose.
The matrix of the test) contains protein and carbohydrates, and vanadocytes (morula cells) wander through the matrix. Deck and his coworkers believed that the vmadocytes contain glycogen but consider
that it does not Contribute to the basic carbohydrate of the test. If the
glycogen was the precursor of the test matrix it would be expected to
occur in the cell in membrane-bounded intra-cellular compartments,
and this is not the case. Furthermore, the vanadocytes do not have a
well-developed Golgi-complex such as would be found in a cell secreting
a glycoprotein material. In the test matrix the vanadocytes appear
most frequently as empty shells, having discharged their contents.
As in Pyura (vide infra) labelled glucose appears rapidly in the cells of
the mantle wall and during a period of five days passes right through
the test. Furthermore the epithelial cells of the mantle, ae in Pyura,
have an abundant endoplasmic reticulum and hypertrophied Golgi
zones suggesting this as the site of active secretion.
(d) Ciona intestinalis (Bierbauer and Vagas, 1962). The test is made
of a fibrillar network containing mucopolysaccharides. Secretion of tevt
material is from the mantle wall. C i o w differs from some other solitary
ascidians in having no blood vessels in the main part of the test but
only in the posterior pedicel (Millar, 1963s) and hence the mantle is the
only possible site for fleeretion of test material. (See also Pdrb, 1948b;
Dilly, 1969a.)
(e) Dendrodoa groesuEaria (Van Beneden) (Barrington and Thorp,
1968). The test is thin but tough and devoid of blood vewle. The
matrix is composed of both acid mucopolysaccharidea and protein
some of which is conjugated as mucoprotein. The toughness of the
test is attributable to proteinaceous fibres coupled with a quinone
tanning system. The test substance appears to be secreted from the
mantle epidermis but unlike some other ascidians the morula cells,
which are rich in glycoyroteiri, do not migrate through the mantle and
appear to contribute materials directly to the epidermis. According
to Barrington and Thorpe the mantle cells probably produce both
carbohydrate and protein and wandering " polyphenol " cells in the
test are responsible for the quinone-tanning system of proteins. This
system may also aid in the process of iodine binding in the tunic
(see p. 28). In this context it is noteworthy that in Ciona (Barrington
and Bmron, 1960) iodineted structural protc?ins are confined to the
outer cuticle of the test, whereas in Dendrodon the procesR of iodination
IVAN UOODBODY
(c) Perophura viridh Vcrrill (Deck et al., 1966) (Fig. 5 ) . The test of
Perophora is much thinner m d more translucent than in Phallusia.
Filaments of about 80 A diameter lie in a homogeneousground substance ;
the structure of those lilanicnts in c.onHistent with their being a cellulose.
The matrix of the test) contains protein and carbohydrates, and vanadocytes (morula cells) wander through the matrix. Deck and his coworkers believed that the vmadocytes contain glycogen but consider
that it does not Contribute to the basic carbohydrate of the test. If the
glycogen was the precursor of the test matrix it would be expected to
occur in the cell in membrane-bounded intra-cellular compartments,
and this is not the case. Furthermore, the vanadocytes do not have a
well-developed Golgi-complex such as would be found in a cell secreting
a glycoprotein material. In the test matrix the vanadocytes appear
most frequently as empty shells, having discharged their contents.
As in Pyura (vide infra) labelled glucose appears rapidly in the cells of
the mantle wall and during a period of five days passes right through
the test. Furthermore the epithelial cells of the mantle, ae in Pyura,
have an abundant endoplasmic reticulum and hypertrophied Golgi
zones suggesting this as the site of active secretion.
(d) Ciona intestinalis (Bierbauer and Vagas, 1962). The test is made
of a fibrillar network containing mucopolysaccharides. Secretion of tevt
material is from the mantle wall. C i o w differs from some other solitary
ascidians in having no blood vessels in the main part of the test but
only in the posterior pedicel (Millar, 1963s) and hence the mantle is the
only possible site for fleeretion of test material. (See also Pdrb, 1948b;
Dilly, 1969a.)
(e) Dendrodoa groesuEaria (Van Beneden) (Barrington and Thorp,
1968). The test is thin but tough and devoid of blood vewle. The
matrix is composed of both acid mucopolysaccharidea and protein
some of which is conjugated as mucoprotein. The toughness of the
test is attributable to proteinaceous fibres coupled with a quinone
tanning system. The test substance appears to be secreted from the
mantle epidermis but unlike some other ascidians the morula cells,
which are rich in glycoyroteiri, do not migrate through the mantle and
appear to contribute materials directly to the epidermis. According
to Barrington and Thorpe the mantle cells probably produce both
carbohydrate and protein and wandering " polyphenol " cells in the
test are responsible for the quinone-tanning system of proteins. This
system may also aid in the process of iodine binding in the tunic
(see p. 28). In this context it is noteworthy that in Ciona (Barrington
and Bmron, 1960) iodineted structural protc?ins are confined to the
outer cuticle of the test, whereas in Dendrodon the procesR of iodination