VITELLINE MEMBRANE AND CORTICAL PARTICLES 267
the cytoplasmic membrane. Endo (1961b) and Runnström and Manelli
(1964) showed that in Polyspermie eggs delayed cortical particles were
found around each site of entrance of a spermatozoon. The number of
particles was higher around one of the penetration sites, probably that
of the spermatozoon that established the first effective attachment to the
egg surface (Runnström and Manelli, loc. cit.). The explanation may
be that a certain movement of cortical cytoplasm takes place in the
direction of the site of sperm attachment. This movement, which is indicated by numerous observations, may bring some of the cortical particles out of their strategic position close to the surface layer. Somewhat
later there may be a backward cytoplasmic movement that brings the
cortical particles in the appropriate position to contact the plasma membrane, which in turn would lead to their opening. Electron micrographs
occasionally indicated that cortical particles may migrate some distance
along with the male nucleus toward the interior of the egg. This occurred, for example, often in Paracentrotus
eggs that had been pretreated
with and inseminated in the presence of ribonuclease (Runnström, 1962).
The extrusion of the lamella could occur with great force in ribonucleasetreated eggs. The lamella could be ejected over a distance of several
microns and penetrate through the fertilization membrane, which in
these eggs, must have pores so wide as to allow the passage of the
lamellae. These were immobilized in the interior part of the jelly coat.
The absence of any Brownian movement seemed to indicate a gelation
of the jelly immediately surrounding the lamellae.
The electronmicrographs consistently show that the single cortical
particles have a rather different orientation of their axes (see Fig. 14).
It may be supposed that a stricter orientation of the particles occurs
shortly before their opening. This must presuppose a certain rotation of
the particles. It seems evident that a final radial orientation of the axes
is a prerequisite for the formation of the stomata, which brings about
an open communication between the interior of the cortical particle and
the perivitelline space.
The cortical particles first open up around the site of effective sperm
attachment, but the process spreads from here over the egg surface. This
corresponds to what Just (1939) described as a wave of activation.
On basis of work on artificial activation of the eggs of the fish Oryzias
latipes, Yamamoto (1949, 1954, 1961) distinguished between the primary
phase (stimulation) and the secondary impulse that spreads over the
egg. The same conception is no doubt valid also for a natural fertilization. An impulse is propagated from the site of effective sperm attachment. The impulse causes the successive opening and evacuation of the
cortical particles, as was shown by Allen (1954) and Sugiyama (1953,
the cytoplasmic membrane. Endo (1961b) and Runnström and Manelli
(1964) showed that in Polyspermie eggs delayed cortical particles were
found around each site of entrance of a spermatozoon. The number of
particles was higher around one of the penetration sites, probably that
of the spermatozoon that established the first effective attachment to the
egg surface (Runnström and Manelli, loc. cit.). The explanation may
be that a certain movement of cortical cytoplasm takes place in the
direction of the site of sperm attachment. This movement, which is indicated by numerous observations, may bring some of the cortical particles out of their strategic position close to the surface layer. Somewhat
later there may be a backward cytoplasmic movement that brings the
cortical particles in the appropriate position to contact the plasma membrane, which in turn would lead to their opening. Electron micrographs
occasionally indicated that cortical particles may migrate some distance
along with the male nucleus toward the interior of the egg. This occurred, for example, often in Paracentrotus
eggs that had been pretreated
with and inseminated in the presence of ribonuclease (Runnström, 1962).
The extrusion of the lamella could occur with great force in ribonucleasetreated eggs. The lamella could be ejected over a distance of several
microns and penetrate through the fertilization membrane, which in
these eggs, must have pores so wide as to allow the passage of the
lamellae. These were immobilized in the interior part of the jelly coat.
The absence of any Brownian movement seemed to indicate a gelation
of the jelly immediately surrounding the lamellae.
The electronmicrographs consistently show that the single cortical
particles have a rather different orientation of their axes (see Fig. 14).
It may be supposed that a stricter orientation of the particles occurs
shortly before their opening. This must presuppose a certain rotation of
the particles. It seems evident that a final radial orientation of the axes
is a prerequisite for the formation of the stomata, which brings about
an open communication between the interior of the cortical particle and
the perivitelline space.
The cortical particles first open up around the site of effective sperm
attachment, but the process spreads from here over the egg surface. This
corresponds to what Just (1939) described as a wave of activation.
On basis of work on artificial activation of the eggs of the fish Oryzias
latipes, Yamamoto (1949, 1954, 1961) distinguished between the primary
phase (stimulation) and the secondary impulse that spreads over the
egg. The same conception is no doubt valid also for a natural fertilization. An impulse is propagated from the site of effective sperm attachment. The impulse causes the successive opening and evacuation of the
cortical particles, as was shown by Allen (1954) and Sugiyama (1953,