292
JOHN RUNNSTRÖM
Β. Experimental Analysis of the Structural Changes in
Lamellae and Extralamellar Bodies
Studies of experimentally treated eggs have thrown some light on the
nature of the changes which the lamellae and the extralamellar bodies
undergo after the opening of the cortical particles. Runnström et al.
(1946) showed that basic proteins extracted from sea urchin sperm or
clupeine gave a granular membrane. This indicates that the sliding has
been prevented. Afzelius (1956) utilized the basic enzyme lysozyme,
which had earlier been used by Runnström and Monroy (1950) in
studies of precipitation of the jelly coat. Lysozyme in sea water (0.002%)
prevents or delays incorporation of the cortical lamellae into the
fertilization membrane of Echinus. After lysozyme treatment a precipitation has taken place within the lamellae. Electron-dense spots are
perceived within a more electron-transparent ground substance. Continued electron-microscopic examination has shown that the precipitated
spots represent contracted filaments, whereas the more transparent parts
are derived from the lamellar matrix (Fig. 1, i and e). This matrix may
coalesce to the previously mentioned larger vacuole within the lamellae.
The extralamellar bodies form a precipitate of thin threads. No separation of components is observed. The surface of the often spherical lamellae
is more heavily precipitated than the inner region, sometimes in the
form of plates that may partially overlap, similar to the tiles on a roof.
Acid components in the lamellae are evidently precipitated by the
lysozyzme. The basic protein seems to have a greater affinity for the
lamellar filaments than for the jelly coat, which is also an acid polysaccharide protein complex (for references see Runnström et al., 1959).
Lysozyme does not precipitate this complex at the ionic strength of sea
water. At lower ionic strength brought about by dilution of sea water
with isotonic cane sugar solution, a heavy fibrillar precipitation occurs
(Runnström and Monroy, 1950). Even in eggs fertilized in the presence
of 0.02% lysozyme the lamellae may enter as components of the fertilization membrane. These lamellae do not flatten out as completely as
under normal conditions, and precipitated spots are distinguished.
Despite the presence of lysozyme, the lamellae and extralamellar
bodies may be separated from each other. It follows from the description
in Section I,B>1 that the lamellae may also be connected with the membrane of the cortical particle, a connection that is broken up at the
release of the lamella. After treatment with basic protein, the breakup
of the previously mentioned connections is blocked to a large extent. In
fact, a number of villi are connected with the lamellae, as indicated in
Fig. 28.
JOHN RUNNSTRÖM
Β. Experimental Analysis of the Structural Changes in
Lamellae and Extralamellar Bodies
Studies of experimentally treated eggs have thrown some light on the
nature of the changes which the lamellae and the extralamellar bodies
undergo after the opening of the cortical particles. Runnström et al.
(1946) showed that basic proteins extracted from sea urchin sperm or
clupeine gave a granular membrane. This indicates that the sliding has
been prevented. Afzelius (1956) utilized the basic enzyme lysozyme,
which had earlier been used by Runnström and Monroy (1950) in
studies of precipitation of the jelly coat. Lysozyme in sea water (0.002%)
prevents or delays incorporation of the cortical lamellae into the
fertilization membrane of Echinus. After lysozyme treatment a precipitation has taken place within the lamellae. Electron-dense spots are
perceived within a more electron-transparent ground substance. Continued electron-microscopic examination has shown that the precipitated
spots represent contracted filaments, whereas the more transparent parts
are derived from the lamellar matrix (Fig. 1, i and e). This matrix may
coalesce to the previously mentioned larger vacuole within the lamellae.
The extralamellar bodies form a precipitate of thin threads. No separation of components is observed. The surface of the often spherical lamellae
is more heavily precipitated than the inner region, sometimes in the
form of plates that may partially overlap, similar to the tiles on a roof.
Acid components in the lamellae are evidently precipitated by the
lysozyzme. The basic protein seems to have a greater affinity for the
lamellar filaments than for the jelly coat, which is also an acid polysaccharide protein complex (for references see Runnström et al., 1959).
Lysozyme does not precipitate this complex at the ionic strength of sea
water. At lower ionic strength brought about by dilution of sea water
with isotonic cane sugar solution, a heavy fibrillar precipitation occurs
(Runnström and Monroy, 1950). Even in eggs fertilized in the presence
of 0.02% lysozyme the lamellae may enter as components of the fertilization membrane. These lamellae do not flatten out as completely as
under normal conditions, and precipitated spots are distinguished.
Despite the presence of lysozyme, the lamellae and extralamellar
bodies may be separated from each other. It follows from the description
in Section I,B>1 that the lamellae may also be connected with the membrane of the cortical particle, a connection that is broken up at the
release of the lamella. After treatment with basic protein, the breakup
of the previously mentioned connections is blocked to a large extent. In
fact, a number of villi are connected with the lamellae, as indicated in
Fig. 28.