264
JOHN RUNNSTRÖM
which jelly coat (either as gel or dissolved as egg water), vitelline membrane, and cytoplasmic surface represent different sites of reaction. This
is the view held also by Colwin and Colwin (1964, p. 275). The early
events of sperm-egg association fall into a series of steps or states. These
will be subject to further discussion below, particularly in Sections II,C,
III,A-D, and IV,B,C. Tyler and his colleagues, on the other hand, consider one step decisive in fertilization, viz., the fertilizin-antifertilizin
reaction (for reviews see Tyler, 1948, 1954, 1959, 1963). This "fertilizin
theory" may account formally for the specificity met in fertilization, but
gives no clue as to how the metabolic changes are triggered. Its emphasis
on specificity has prompted, however, the utilization of serological
methods in the study of fertilization. An extensive survey of this work
is, however, beyond the scope of this article.
B. The Mechanism of Separation of the Vitelline Membrane
from the Plasma Surface
The attachment of the spermatozoon to the cytoplasmic surface of the
egg induces the elevation of the vitelline membrane and the opening of
the cortical particles. The vitelline membrane slides over the surface of
the spermatozoon and the middle piece, whereas the end of the tail may
project through the fertilization membrane for 10 to 12 min
(Paracentrotus) .
It follows from different observations that the separation and beginning elevation of the vitelline membrane somewhat precedes the opening of the cortical particles; Runnström (1948) observed, for example,
that in eggs of Εchinocardium
an extremely thin membrane elevated and
became more conspicuous by gradual incorporation of material from the
cortical particles. Similar observations were made later on eggs of
Psammechinus
microtuberculatus
(Runnström, 1952a). Electron-microscopic studies showed also that the elevation of the vitelline membrane
precedes that of the opening of the cortical particles (Runnström, unpublished results, 1964). The question arises as to how the close attachment of the vitelline membrane to the egg surface is broken up in
fertilization or artificial parthenogenesis.
Isaka and Aikawa (1963a,b) suggested that in the nonactivated egg
the vitelline membrane may be attached to the egg surface by means of
hydrogen bonds. This suggestion is supported by a considerable number
of observations demonstrating how substances which are able to break
hydrogen bonds also provoke an elevation of the fertilization membrane
in the sea urchin Hemicentrotus
pulcherrimus
and the echiuroid Urechis
unicinctus.
The analysis carried out by the mentioned workers on the action of a
JOHN RUNNSTRÖM
which jelly coat (either as gel or dissolved as egg water), vitelline membrane, and cytoplasmic surface represent different sites of reaction. This
is the view held also by Colwin and Colwin (1964, p. 275). The early
events of sperm-egg association fall into a series of steps or states. These
will be subject to further discussion below, particularly in Sections II,C,
III,A-D, and IV,B,C. Tyler and his colleagues, on the other hand, consider one step decisive in fertilization, viz., the fertilizin-antifertilizin
reaction (for reviews see Tyler, 1948, 1954, 1959, 1963). This "fertilizin
theory" may account formally for the specificity met in fertilization, but
gives no clue as to how the metabolic changes are triggered. Its emphasis
on specificity has prompted, however, the utilization of serological
methods in the study of fertilization. An extensive survey of this work
is, however, beyond the scope of this article.
B. The Mechanism of Separation of the Vitelline Membrane
from the Plasma Surface
The attachment of the spermatozoon to the cytoplasmic surface of the
egg induces the elevation of the vitelline membrane and the opening of
the cortical particles. The vitelline membrane slides over the surface of
the spermatozoon and the middle piece, whereas the end of the tail may
project through the fertilization membrane for 10 to 12 min
(Paracentrotus) .
It follows from different observations that the separation and beginning elevation of the vitelline membrane somewhat precedes the opening of the cortical particles; Runnström (1948) observed, for example,
that in eggs of Εchinocardium
an extremely thin membrane elevated and
became more conspicuous by gradual incorporation of material from the
cortical particles. Similar observations were made later on eggs of
Psammechinus
microtuberculatus
(Runnström, 1952a). Electron-microscopic studies showed also that the elevation of the vitelline membrane
precedes that of the opening of the cortical particles (Runnström, unpublished results, 1964). The question arises as to how the close attachment of the vitelline membrane to the egg surface is broken up in
fertilization or artificial parthenogenesis.
Isaka and Aikawa (1963a,b) suggested that in the nonactivated egg
the vitelline membrane may be attached to the egg surface by means of
hydrogen bonds. This suggestion is supported by a considerable number
of observations demonstrating how substances which are able to break
hydrogen bonds also provoke an elevation of the fertilization membrane
in the sea urchin Hemicentrotus
pulcherrimus
and the echiuroid Urechis
unicinctus.
The analysis carried out by the mentioned workers on the action of a