VITELLINE MEMBRANE AND CORTICAL PARTICLES 305
corresponds to Markman's period of minimum resistance. The fertilization membrane has now lost its elasticity. This may mean that lamellar
filaments that initially can be displaced relative to each other have now
been linked together by the polymerization process, as indicated in
Fig. 32B. This prevents the membrane from shrinking, with decrease of
its surface. On the other hand, the membrane has not yet attained the
solidity that resists the folding which it sustains during the passage
through the meshes under increased pressure. The increase in resistance
of the membrane occurring from 3 to 4 min after insemination must
be due to a reinforced linkage between the lamellar filaments and also
between these filaments and the filling substance which may also undergo
gelation. At 4 min after insemination the solidity of the fertilization
membrane increases in Endo's experiments, as follows from a changed
behavior of the fertilization membrane after transfer to the gum arabic
solution. An increasing part of the fertilization membrane remains
smooth and expanded. This final change starts from the point of sperm
entrance and spreads gradually in the distal direction. The end-point
stability seems to be attained slightly earlier in Markman's experiments
than in those of Endo.
Kopac (1941) stated that the fertilization membrane (the "transitional" membrane) is soluble in isomotic urea or KCl solution during
its elevation. This proves that the first polymerization process involved
weak linkages. This is also in keeping with the fragility of the fertilization
membrane during its elevation. Ishida (1936) and Kopac (1941) found
that the membrane in the transitional state is extremely sensitive to the
action of the "hatching enzyme." As the name indicates this enzyme
breaks down the fertilization membrane at hatching in the blastula
stage. The final fertilization membrane is inelastic, as was shown by
means of micromanipulation (Peterfi, 1933). It is not only mechanically
but also chemically more resistant than the transitional membrane. It is
only slowly broken down by the hatching enzyme ; 1-3 hr exposures were
required for complete disintegration. Ishida (1936), the discoverer of this
enzyme, considered it to be a specific "proteoclastic" enzyme. The evidence points to the conclusion that stronger linkages arise in the final
fertilization membrane. Nevertheless, one parameter remains constant
from the moment of the progressive smoothening of the membrane 3040 sec after fertilization. Even a still somewhat folded membrane shows
the retardation of ca. 12.5 τημ in the transitional stage, and the same
value is found in the tough final membrane. Some basic structural
arrangement may remain unchanged from the moment of incorporation
of the lamellar component, which agrees with the diagrams in Figs. 32A
corresponds to Markman's period of minimum resistance. The fertilization membrane has now lost its elasticity. This may mean that lamellar
filaments that initially can be displaced relative to each other have now
been linked together by the polymerization process, as indicated in
Fig. 32B. This prevents the membrane from shrinking, with decrease of
its surface. On the other hand, the membrane has not yet attained the
solidity that resists the folding which it sustains during the passage
through the meshes under increased pressure. The increase in resistance
of the membrane occurring from 3 to 4 min after insemination must
be due to a reinforced linkage between the lamellar filaments and also
between these filaments and the filling substance which may also undergo
gelation. At 4 min after insemination the solidity of the fertilization
membrane increases in Endo's experiments, as follows from a changed
behavior of the fertilization membrane after transfer to the gum arabic
solution. An increasing part of the fertilization membrane remains
smooth and expanded. This final change starts from the point of sperm
entrance and spreads gradually in the distal direction. The end-point
stability seems to be attained slightly earlier in Markman's experiments
than in those of Endo.
Kopac (1941) stated that the fertilization membrane (the "transitional" membrane) is soluble in isomotic urea or KCl solution during
its elevation. This proves that the first polymerization process involved
weak linkages. This is also in keeping with the fragility of the fertilization
membrane during its elevation. Ishida (1936) and Kopac (1941) found
that the membrane in the transitional state is extremely sensitive to the
action of the "hatching enzyme." As the name indicates this enzyme
breaks down the fertilization membrane at hatching in the blastula
stage. The final fertilization membrane is inelastic, as was shown by
means of micromanipulation (Peterfi, 1933). It is not only mechanically
but also chemically more resistant than the transitional membrane. It is
only slowly broken down by the hatching enzyme ; 1-3 hr exposures were
required for complete disintegration. Ishida (1936), the discoverer of this
enzyme, considered it to be a specific "proteoclastic" enzyme. The evidence points to the conclusion that stronger linkages arise in the final
fertilization membrane. Nevertheless, one parameter remains constant
from the moment of the progressive smoothening of the membrane 3040 sec after fertilization. Even a still somewhat folded membrane shows
the retardation of ca. 12.5 τημ in the transitional stage, and the same
value is found in the tough final membrane. Some basic structural
arrangement may remain unchanged from the moment of incorporation
of the lamellar component, which agrees with the diagrams in Figs. 32A