224
JOHN RUNNSTRÖM
plasmin (Runnström and Kriszat, unpublished data, 1964) proved also
capable of attacking the vitelline membrane. This shows that lysine,
arginine, and tyrosine are all present as components in the vitelline
membrane of the species concerned and are critical for its continuity.
Thrombin was inactive, which is in keeping with the high specificity of
this enzyme. The eggs of Echinocardium
cordatum behaved somewhat
exceptionally, since treatment with trypsin, which causes dissolution of
the vitelline membrane in other species, here caused an elevation of the
fertilization membrane (Runnström, 1948). The same was found by
Moore (1951) to hold for Dendraster excentricus. According to Minganti
(1954) the vitelline membrane must be somewhat more resistant against
trypsin in oocytes than in mature eggs of Psammechinus
miliaris.
Runnström (1948) and Monroy and Runnström (1948) suggested that
the properties of the vitelline membrane in sea urchin eggs may be explained by assuming that it is constituted of two main components: (1)
rather loosely linked fibrous proteins and (2) more complicated proteins of globular type. The first component is mainly responsible for the
trypsin sensitivity; by its breakdown the globular proteins may be released and scattered as in the experiments concerning the action of A III
on oocytes referred to above.
The electron micrographs published by Lönning (1964) and by Baxandall et al. (1964b) give support to the view that the vitelline membrane has a composite structure; thicker and thinner regions alternate,
although in a less pronounced way than before maturation. Upon treatment with 0.001% trypsin it seemed evident from unpublished material
(Runnström, 1964), that a ground substance in the vitelline membrane
became diffuse, whereas granular components were still delimited.
After exposure to a higher concentration of trypsin, the vitelline membrane was fully removed, as indicated by both electron micrographs and observations on fertilization of the pretreated eggs. It remains unsettled as to whether both the main components are broken
down by the enzyme action or whether the granular components are
only released into the medium.
Baxandall et al. (1964b) carried out an investigation in which the
reaction of the surface layers of Paracentrotus
eggs with ferritin-labeled
antiegg γ-globulins were studied with electron microscopy on thin sections. They showed by this method that the vitelline membrane is rich
in both heat-stable and heat-labile egg antigens. After the antiegg γglobulin had been absorbed to detect heat-labile antigen and heatstable insoluble antigen, the vitelline membrane separated from the
cytoplasmic surface and was elevated to some extent, but at certain
intervals connections with the cytoplasmic surface seemed to remain (Fig.
JOHN RUNNSTRÖM
plasmin (Runnström and Kriszat, unpublished data, 1964) proved also
capable of attacking the vitelline membrane. This shows that lysine,
arginine, and tyrosine are all present as components in the vitelline
membrane of the species concerned and are critical for its continuity.
Thrombin was inactive, which is in keeping with the high specificity of
this enzyme. The eggs of Echinocardium
cordatum behaved somewhat
exceptionally, since treatment with trypsin, which causes dissolution of
the vitelline membrane in other species, here caused an elevation of the
fertilization membrane (Runnström, 1948). The same was found by
Moore (1951) to hold for Dendraster excentricus. According to Minganti
(1954) the vitelline membrane must be somewhat more resistant against
trypsin in oocytes than in mature eggs of Psammechinus
miliaris.
Runnström (1948) and Monroy and Runnström (1948) suggested that
the properties of the vitelline membrane in sea urchin eggs may be explained by assuming that it is constituted of two main components: (1)
rather loosely linked fibrous proteins and (2) more complicated proteins of globular type. The first component is mainly responsible for the
trypsin sensitivity; by its breakdown the globular proteins may be released and scattered as in the experiments concerning the action of A III
on oocytes referred to above.
The electron micrographs published by Lönning (1964) and by Baxandall et al. (1964b) give support to the view that the vitelline membrane has a composite structure; thicker and thinner regions alternate,
although in a less pronounced way than before maturation. Upon treatment with 0.001% trypsin it seemed evident from unpublished material
(Runnström, 1964), that a ground substance in the vitelline membrane
became diffuse, whereas granular components were still delimited.
After exposure to a higher concentration of trypsin, the vitelline membrane was fully removed, as indicated by both electron micrographs and observations on fertilization of the pretreated eggs. It remains unsettled as to whether both the main components are broken
down by the enzyme action or whether the granular components are
only released into the medium.
Baxandall et al. (1964b) carried out an investigation in which the
reaction of the surface layers of Paracentrotus
eggs with ferritin-labeled
antiegg γ-globulins were studied with electron microscopy on thin sections. They showed by this method that the vitelline membrane is rich
in both heat-stable and heat-labile egg antigens. After the antiegg γglobulin had been absorbed to detect heat-labile antigen and heatstable insoluble antigen, the vitelline membrane separated from the
cytoplasmic surface and was elevated to some extent, but at certain
intervals connections with the cytoplasmic surface seemed to remain (Fig.