300
JOHN RUNNSTRÖM
phenomenon of formation of lipoprotein blister referred to above (Section
II,D). There must be a close connection between the state of the hyaline
layer, primarily its villi, and the structure of the interior cytoplasm.
The acid polysaccharides of the hyaline layer and their moieties of
protein or lipid must correspond to the matrix of the proximal region
öf the cortical particles. It is possible that a secretion process from the
cortical cytoplasm is also involved in the formation of these acid mucopolysaccharides. Anyhow, in more advanced stages of development a
secretion occurs. This is proved by the disappearance of the Hale reaction in late blastulae transferred to sulfate-free sea water, as shown
by Immers (1956). The same author demonstrated the presence of acid
mucopolysaccharides in the perivitelline space in Echinus
esculentus.
These may originate from the matrix of the distal region of the cortical
particles—a material that is exuded immediately after the opening of
these particles. This release of substances rich in acid mucopolysaccharides has been subject to a new thorough study by Ishihara (1964).
C. Concavity Formation in the Egg Surface and the
Smoothening of the Fertilization Membrane
The formation of a concavity in the proximal region of the egg has
been mentioned previously (Section H,D). Phase-contrast pictures of the
concavity in normal Paracentrotus
eggs may be found in work by
Runnström (1962, Figs. 1-5). The concavity is first perceived at 20-30
sec after (rapid) insemination, attains its full development at about 45
sec, and disappears at 50-60 sec after insemination. The attached
spermatozoon is usually found in the center of the fully developed concavity; 45 sec after insemination the diameter of the concavity was
about 60 μ. The changes in the egg surface were followed by successive
fixations in 4% neutral formaldehyde. The observations on this material
showed that the fertilization membrane first becomes smooth in a region
that only slightly extends beyond the border of the concavity (Runnström, 1962, Fig. 2).
In the distal region (relative to the concavity) the fertilization membrane appears granular. This is, however, not due to an incomplete incorporation of the lamellae but to the presence of connections between
the egg surface and the membrane corresponding to the conditions illustrated in Fig. 30. In normal eggs these connections are broken 60-70
sec after insemination (Section ΙΙΙ,Β). In phase contrast the smooth
membrane looks darker than the granular membrane, but the retardation does not change. The electron-microscopic study shows that the egg
surface is rather smooth within the concavity. The villi are retracted;
this is the cause of the rather great increase in surface that the con-
JOHN RUNNSTRÖM
phenomenon of formation of lipoprotein blister referred to above (Section
II,D). There must be a close connection between the state of the hyaline
layer, primarily its villi, and the structure of the interior cytoplasm.
The acid polysaccharides of the hyaline layer and their moieties of
protein or lipid must correspond to the matrix of the proximal region
öf the cortical particles. It is possible that a secretion process from the
cortical cytoplasm is also involved in the formation of these acid mucopolysaccharides. Anyhow, in more advanced stages of development a
secretion occurs. This is proved by the disappearance of the Hale reaction in late blastulae transferred to sulfate-free sea water, as shown
by Immers (1956). The same author demonstrated the presence of acid
mucopolysaccharides in the perivitelline space in Echinus
esculentus.
These may originate from the matrix of the distal region of the cortical
particles—a material that is exuded immediately after the opening of
these particles. This release of substances rich in acid mucopolysaccharides has been subject to a new thorough study by Ishihara (1964).
C. Concavity Formation in the Egg Surface and the
Smoothening of the Fertilization Membrane
The formation of a concavity in the proximal region of the egg has
been mentioned previously (Section H,D). Phase-contrast pictures of the
concavity in normal Paracentrotus
eggs may be found in work by
Runnström (1962, Figs. 1-5). The concavity is first perceived at 20-30
sec after (rapid) insemination, attains its full development at about 45
sec, and disappears at 50-60 sec after insemination. The attached
spermatozoon is usually found in the center of the fully developed concavity; 45 sec after insemination the diameter of the concavity was
about 60 μ. The changes in the egg surface were followed by successive
fixations in 4% neutral formaldehyde. The observations on this material
showed that the fertilization membrane first becomes smooth in a region
that only slightly extends beyond the border of the concavity (Runnström, 1962, Fig. 2).
In the distal region (relative to the concavity) the fertilization membrane appears granular. This is, however, not due to an incomplete incorporation of the lamellae but to the presence of connections between
the egg surface and the membrane corresponding to the conditions illustrated in Fig. 30. In normal eggs these connections are broken 60-70
sec after insemination (Section ΙΙΙ,Β). In phase contrast the smooth
membrane looks darker than the granular membrane, but the retardation does not change. The electron-microscopic study shows that the egg
surface is rather smooth within the concavity. The villi are retracted;
this is the cause of the rather great increase in surface that the con-