VITELLINE MEMBRANE AND CORTICAL PARTICLES 259
The matrix could possibly undergo a change from the nonsoluble to a
soluble form when the cortical particles become located within the cortex
following the maturation of the egg. The underripeness of the egg
(Runnström, 1964) could depend on a delay in the changes taking place
in the matrix. It may be remembered that the jelly coat in underripe
eggs is dense and rather inaccessible to break-up by spermatozoa
(Runnström, 1964). Parallel changes may occur in the matrix of the
cortical particles and in the substance of the jelly coat. These substances
are both rich in sulfated polysaccharides, but the sugar monomers are
different (Immers, loc. cit.) ; the sulfated polysaccharides from the cytoplasm contain glucose amine which is absent from the substance of the
jelly coat (Immers and Vasseur, 1950). For permeability reasons, the
cortical particles may not be freely accessible to antiegg γ-globulin.
NeverthelesSj Baxandall et al. (1964b) observed that it reacted with
both the lamella and the membrane of the cortical particles. Consequently, they contain egg antigens. These are not identical with the
proper antigens of the jelly coat (see Perlmann, 1959). Afzelius (1956)
found that methylmercury chloride was an excellent electron-microscopic
stain for the cortical particles. The mercury reacts first with SH groups
which indicates that the cortical particles are rich in SH groups. These
may be important for the stability of the inner structures of the cortical
particles. For further information on the cytoplasm of the
Paracentrotus
and its particulate components, the reader is referred to the papers by
Pasteels (1958) and Pasteels et al. (1958).
II. Vitelline Membrane and Cortical Particles in the
Fertilization Process
A. Sperm Attachment and the Role of the Surface Layers
Afzelius and Murray (1957) studied with the aid of electron microscopy the initial interaction between spermatozoon and the egg surface
in a number of sea urchins, particularly Strongylocentrotus
droebachiensis and Psammechinus
miliaris. They showed that the spermatozoon in
contact with the egg surface underwent the so-called acrosomal reaction
—an elongation of the acrosomal region to a tubule with ensuing stretching of the fibrous material present in the innermost part of the acrosomal
cavity (loc. cit., Fig. 5). At the same time, the acrosomal globule is
secreted; this is visible before reaction in the foremost part of the
acrosomal cavity.
The acrosomal changes may also occur without contact with the egg
surface, e.g., under the influence of "egg water," i.e., sea water that has
been in contact with eggs for some time. These phenomena have been
The matrix could possibly undergo a change from the nonsoluble to a
soluble form when the cortical particles become located within the cortex
following the maturation of the egg. The underripeness of the egg
(Runnström, 1964) could depend on a delay in the changes taking place
in the matrix. It may be remembered that the jelly coat in underripe
eggs is dense and rather inaccessible to break-up by spermatozoa
(Runnström, 1964). Parallel changes may occur in the matrix of the
cortical particles and in the substance of the jelly coat. These substances
are both rich in sulfated polysaccharides, but the sugar monomers are
different (Immers, loc. cit.) ; the sulfated polysaccharides from the cytoplasm contain glucose amine which is absent from the substance of the
jelly coat (Immers and Vasseur, 1950). For permeability reasons, the
cortical particles may not be freely accessible to antiegg γ-globulin.
NeverthelesSj Baxandall et al. (1964b) observed that it reacted with
both the lamella and the membrane of the cortical particles. Consequently, they contain egg antigens. These are not identical with the
proper antigens of the jelly coat (see Perlmann, 1959). Afzelius (1956)
found that methylmercury chloride was an excellent electron-microscopic
stain for the cortical particles. The mercury reacts first with SH groups
which indicates that the cortical particles are rich in SH groups. These
may be important for the stability of the inner structures of the cortical
particles. For further information on the cytoplasm of the
Paracentrotus
and its particulate components, the reader is referred to the papers by
Pasteels (1958) and Pasteels et al. (1958).
II. Vitelline Membrane and Cortical Particles in the
Fertilization Process
A. Sperm Attachment and the Role of the Surface Layers
Afzelius and Murray (1957) studied with the aid of electron microscopy the initial interaction between spermatozoon and the egg surface
in a number of sea urchins, particularly Strongylocentrotus
droebachiensis and Psammechinus
miliaris. They showed that the spermatozoon in
contact with the egg surface underwent the so-called acrosomal reaction
—an elongation of the acrosomal region to a tubule with ensuing stretching of the fibrous material present in the innermost part of the acrosomal
cavity (loc. cit., Fig. 5). At the same time, the acrosomal globule is
secreted; this is visible before reaction in the foremost part of the
acrosomal cavity.
The acrosomal changes may also occur without contact with the egg
surface, e.g., under the influence of "egg water," i.e., sea water that has
been in contact with eggs for some time. These phenomena have been