398
CH. DEVILLERS
its physico-chemical properties (Devillers, 1948a, d; Trinkaus, 1948,
1949b) are comparable to those of the cortex in Amphibia, it must
contain the same constituents under one form or another.
The term cortex (Devillers, 1948a) is synonymous with superficial
gel layer (Lewis, 1949a, b) or surface gel layer (Trinkaus, 1949b). It does
not correspond only to the 'surface coat' of Holtfreter as stated by
Trinkaus.
1. The Cortical Alveolae
The first step in cortical development is the dissolution of the alveolae
(Yamamoto, 1939) representing the remains of the alveolar layer of the
oocyte, before the period of major growth (Arndt, 1960; Τ. S. Yamamoto, 1955). Without going into details of the structure of the alveolae
and the propagation of the dissolution process (see papers by Aketa,
1954; Kagan, 1935; Kanoh, 1957; Kao et ah, 1954b; Kusa, 1953a, b, c;
Thomopoulos, 1953a, b, 1954; Yamamoto, 1945b, 1956) we can note
that, in normal development, the disappearance of the alveolae is propagated from the blastodermal pole towards the opposite pole (wave of
fertilization of Yamamoto, 1944). This dissolution of the alveolae is connected with the formation of the perivitelline space. Bipolar differentiation, which comes next, is not causally connected with the dissolution.
The latter can be inhibited without stopping either bipolar differentiation or development (Kanoh, 1952a, 1957; Kanoh and Yanagimachi,
1956; Kusa, 1953c; T. Yamamoto, 1956; T. S. Yamamoto, 1957).
The alveolae nearly touch each other in the cortex and they open
widely to the outside when they disappear. The whole primitive surface
of the egg must also disappear and a new surface be formed by junction
of the alveolar walls.
2. The Properties of the Cortex
The primary cortex is permeable, at least for a time; the secondary
cortex is impermeable, or at least only very slightly permeable (see
Section III, C, 2, b); it is non-adhesive (Devillers, 1948a; Trinkaus,
1948, 1949b), elastic and contractile; it unites the surface blastomeres
tightly together (enveloping layer). These properties are not all found in
the other cellular walls of the germ, and they confer on the cortex, and
then on the enveloping layer, a special part in development.
a. Formation of the cortex
Since it is the only cell layer to form itself in contact with the exterior
medium, it could be thought that the latter, and especially the ions it
contains, gives to the cortex its particular properties. This problem has
not yet been studied, and we do not know the evolution of the structure
CH. DEVILLERS
its physico-chemical properties (Devillers, 1948a, d; Trinkaus, 1948,
1949b) are comparable to those of the cortex in Amphibia, it must
contain the same constituents under one form or another.
The term cortex (Devillers, 1948a) is synonymous with superficial
gel layer (Lewis, 1949a, b) or surface gel layer (Trinkaus, 1949b). It does
not correspond only to the 'surface coat' of Holtfreter as stated by
Trinkaus.
1. The Cortical Alveolae
The first step in cortical development is the dissolution of the alveolae
(Yamamoto, 1939) representing the remains of the alveolar layer of the
oocyte, before the period of major growth (Arndt, 1960; Τ. S. Yamamoto, 1955). Without going into details of the structure of the alveolae
and the propagation of the dissolution process (see papers by Aketa,
1954; Kagan, 1935; Kanoh, 1957; Kao et ah, 1954b; Kusa, 1953a, b, c;
Thomopoulos, 1953a, b, 1954; Yamamoto, 1945b, 1956) we can note
that, in normal development, the disappearance of the alveolae is propagated from the blastodermal pole towards the opposite pole (wave of
fertilization of Yamamoto, 1944). This dissolution of the alveolae is connected with the formation of the perivitelline space. Bipolar differentiation, which comes next, is not causally connected with the dissolution.
The latter can be inhibited without stopping either bipolar differentiation or development (Kanoh, 1952a, 1957; Kanoh and Yanagimachi,
1956; Kusa, 1953c; T. Yamamoto, 1956; T. S. Yamamoto, 1957).
The alveolae nearly touch each other in the cortex and they open
widely to the outside when they disappear. The whole primitive surface
of the egg must also disappear and a new surface be formed by junction
of the alveolar walls.
2. The Properties of the Cortex
The primary cortex is permeable, at least for a time; the secondary
cortex is impermeable, or at least only very slightly permeable (see
Section III, C, 2, b); it is non-adhesive (Devillers, 1948a; Trinkaus,
1948, 1949b), elastic and contractile; it unites the surface blastomeres
tightly together (enveloping layer). These properties are not all found in
the other cellular walls of the germ, and they confer on the cortex, and
then on the enveloping layer, a special part in development.
a. Formation of the cortex
Since it is the only cell layer to form itself in contact with the exterior
medium, it could be thought that the latter, and especially the ions it
contains, gives to the cortex its particular properties. This problem has
not yet been studied, and we do not know the evolution of the structure