258
JOHN RUNNSTRÖM
ever, to give a more evident staining. This stain which was used in more
recent experiments carried out by Immers gave results parallel to those
obtained with the Hale reagent. This points to the conclusion that the
acid group of polysaccharides is mainly responsible for the staining with
Alcian blue. This stain was, nevertheless, very useful as a complement
to the Hale staining; in such cases as the mature Paracentrotus
egg,
Alcian blue gave a better contrast.
The stainability with the Hale reagent or with Alcian blue means
that the linkage between polysaccharide sulfate and protein is weak.
This change may be more pronounced in species such as Arbacia,
Echinocardium, and Echinus
(Immers, 1960) or Pseudocentrotus
depressus
(Aketa, 1962), whereas in Paracentrotus
and Psammechinus
a certain
degree of masking persists even in the mature egg.
In Aketa's Fig. 1, representing the unfertilized egg of
Pseudocentrotus
depressus, the single cortical particles are seen to be stained by Alcian
blue, whereas the surrounding cortex is not stained. This does not exclude the possibility, however, that masked acid polysaccharides are
present in the cortex outside the particles. Immers' (1961b) autoradiographic studies on incorporation of S
3 5
0 4 -sulfate in unfertilized eggs
of Echinus esculentus indicate that it is incorporated only in the cortical
particles but not in the surrounding cortical cytoplasm (see Immers,
1961b, Fig. 8). In Paracentrotus,
however, there seems to be a continuous
surface layer of sulfated compounds. It is, however, difficult to decide
whether this is due to the presence of sulfated compounds outside the
particles or to a closer packing of the cortical particles. It will again be
necessary to resort to higher resolution autoradiography in order to solve
this question. In view of the strong labeling within the cytoplasm of the
oocyte, the question arises as to whether the sulfated compounds are
really used up in the differentiation of the cortical particles or whether
there is, in addition, a secretory process taking place which results in a
decrease of the content of sulfated polysaccharides in the cytoplasm
outside the cortical particles. The question may also be raised as to
whether all the components of the cortical particles are involved in the
unmasking. Most probably the matrix of the cortical particles is the
main site of unmasking. The change within the matrix could be a preparation for the opening of the particle occurring upon fertilization.
Immers (unpublished data, 1964) has extracted the acid polysaccharides
from unfertilized eggs and found two fractions, both rich in sulfate. The
one component is water-soluble and accessible to precipitation by basic
dyes; the other is not water-soluble and was not accessible to precipitation by basic dyes. The latter form could be made soluble and "unmasked" by rather weak acid treatment.
JOHN RUNNSTRÖM
ever, to give a more evident staining. This stain which was used in more
recent experiments carried out by Immers gave results parallel to those
obtained with the Hale reagent. This points to the conclusion that the
acid group of polysaccharides is mainly responsible for the staining with
Alcian blue. This stain was, nevertheless, very useful as a complement
to the Hale staining; in such cases as the mature Paracentrotus
egg,
Alcian blue gave a better contrast.
The stainability with the Hale reagent or with Alcian blue means
that the linkage between polysaccharide sulfate and protein is weak.
This change may be more pronounced in species such as Arbacia,
Echinocardium, and Echinus
(Immers, 1960) or Pseudocentrotus
depressus
(Aketa, 1962), whereas in Paracentrotus
and Psammechinus
a certain
degree of masking persists even in the mature egg.
In Aketa's Fig. 1, representing the unfertilized egg of
Pseudocentrotus
depressus, the single cortical particles are seen to be stained by Alcian
blue, whereas the surrounding cortex is not stained. This does not exclude the possibility, however, that masked acid polysaccharides are
present in the cortex outside the particles. Immers' (1961b) autoradiographic studies on incorporation of S
3 5
0 4 -sulfate in unfertilized eggs
of Echinus esculentus indicate that it is incorporated only in the cortical
particles but not in the surrounding cortical cytoplasm (see Immers,
1961b, Fig. 8). In Paracentrotus,
however, there seems to be a continuous
surface layer of sulfated compounds. It is, however, difficult to decide
whether this is due to the presence of sulfated compounds outside the
particles or to a closer packing of the cortical particles. It will again be
necessary to resort to higher resolution autoradiography in order to solve
this question. In view of the strong labeling within the cytoplasm of the
oocyte, the question arises as to whether the sulfated compounds are
really used up in the differentiation of the cortical particles or whether
there is, in addition, a secretory process taking place which results in a
decrease of the content of sulfated polysaccharides in the cytoplasm
outside the cortical particles. The question may also be raised as to
whether all the components of the cortical particles are involved in the
unmasking. Most probably the matrix of the cortical particles is the
main site of unmasking. The change within the matrix could be a preparation for the opening of the particle occurring upon fertilization.
Immers (unpublished data, 1964) has extracted the acid polysaccharides
from unfertilized eggs and found two fractions, both rich in sulfate. The
one component is water-soluble and accessible to precipitation by basic
dyes; the other is not water-soluble and was not accessible to precipitation by basic dyes. The latter form could be made soluble and "unmasked" by rather weak acid treatment.