230
JOHN RUNNSTRÖM
the cortical particles the lamella, the extralamellar bodies, and the
matrix were distinguished. They are surrounded by the membrane, ca.
100 Â thick.
The lamella has the form of a somewhat irregular plate with narrower
peripheral shanks. These to some extent resemble the spokes of a wheel
without the rim. The number of shanks seems to vary, from 4 to 5 are
often recognizable. The shanks are in contact with the membrane and
are fixed to it. The shanks of the lamella are evidently not strictly in
the same plane as the central region of the lamella, but they are slightly
curved. Possibly this region is also slightly curved, as the highly schematic Fig. 3 would indicate. The point of attachment to the membrane
was, therefore, not always visible. The membrane is indented where the
shanks seem to approach the membrane. This was observed often enough
to suggest that the shanks are united with the membrane. Sometimes
the shanks are seen to become broader and flatter in their outer region,
as if they adapted their form to contact the membrane (Fig. 2, arrow).
In this way there is a tendency to form a rim of the wheel. The indentations of the membrane give strong evidence of the reality of the
attachment of the shank to the membrane. In the lamella a fine structure is often seen, as illustrated in Fig. 2. Parallel denser streaks alternate with streaks of lower density. The distance between the denser
streaks is about 200 Â. A sort of periodicity could also be observed that
was perpendicular to the streaks. The fine structure appeared then as
rows of parallelograms with the longer sides coinciding with the denser
streak. The distance between the shorter sides in the parallelograms was
ca. 600 Â.
The streaks in lamellas of two almost adjacent cortical particles could
form an angle with each other. Thus, exterior action, for example by a
microtome knife, cannot be the cause of the streak structure.
The direction of the streaks is usually identical in a whole lamella;
they may form any angle with the direction of the shanks. They thus
give the impression of being products of a secondary ordering in the
lamellar ground substance, which involves the attainment of a more
stable and solid state.
The number and form of the extralamellar bodies seems to vary somewhat. There may be two, three, or four. Their position is between the
shanks of the lamella as seen in Figs. 2, 4. Often they are seen to be
connected with the lamella by means of fine fibers which may attain
the thickness of 100 Â (Fig. 4, arrow). The extralamellar bodies are not
seen to be connected with the membrane by a broad array of filaments.
Some connections were visile at the place where the shanks attach
themselves to the membrane, see Fig. 3.
JOHN RUNNSTRÖM
the cortical particles the lamella, the extralamellar bodies, and the
matrix were distinguished. They are surrounded by the membrane, ca.
100 Â thick.
The lamella has the form of a somewhat irregular plate with narrower
peripheral shanks. These to some extent resemble the spokes of a wheel
without the rim. The number of shanks seems to vary, from 4 to 5 are
often recognizable. The shanks are in contact with the membrane and
are fixed to it. The shanks of the lamella are evidently not strictly in
the same plane as the central region of the lamella, but they are slightly
curved. Possibly this region is also slightly curved, as the highly schematic Fig. 3 would indicate. The point of attachment to the membrane
was, therefore, not always visible. The membrane is indented where the
shanks seem to approach the membrane. This was observed often enough
to suggest that the shanks are united with the membrane. Sometimes
the shanks are seen to become broader and flatter in their outer region,
as if they adapted their form to contact the membrane (Fig. 2, arrow).
In this way there is a tendency to form a rim of the wheel. The indentations of the membrane give strong evidence of the reality of the
attachment of the shank to the membrane. In the lamella a fine structure is often seen, as illustrated in Fig. 2. Parallel denser streaks alternate with streaks of lower density. The distance between the denser
streaks is about 200 Â. A sort of periodicity could also be observed that
was perpendicular to the streaks. The fine structure appeared then as
rows of parallelograms with the longer sides coinciding with the denser
streak. The distance between the shorter sides in the parallelograms was
ca. 600 Â.
The streaks in lamellas of two almost adjacent cortical particles could
form an angle with each other. Thus, exterior action, for example by a
microtome knife, cannot be the cause of the streak structure.
The direction of the streaks is usually identical in a whole lamella;
they may form any angle with the direction of the shanks. They thus
give the impression of being products of a secondary ordering in the
lamellar ground substance, which involves the attainment of a more
stable and solid state.
The number and form of the extralamellar bodies seems to vary somewhat. There may be two, three, or four. Their position is between the
shanks of the lamella as seen in Figs. 2, 4. Often they are seen to be
connected with the lamella by means of fine fibers which may attain
the thickness of 100 Â (Fig. 4, arrow). The extralamellar bodies are not
seen to be connected with the membrane by a broad array of filaments.
Some connections were visile at the place where the shanks attach
themselves to the membrane, see Fig. 3.