4.12.
MARAGLAS EMBEDDING
115
is a "smudging" or "mottling" of the section as Fig. 11 illustrates. Interestingly enough, and perhaps informative, the effect is rarely if ever seen
when a diamond knife is employed, and yet may be unavoidable when
a glass knife is used. This would suggest that adhesive forces exist during
sectioning between some component of the block and glass. Because of
this it can be imagined that surface particles are dragged along as the
knife passes the block, or the section glides over the knife edge. Exactly
this is known to occur in many types of polishing actions. Indeed it is in
just this manner that a soft polishing agent like rouge can polish hard
steel. I have the impression that this effect is associated with blocks that
do not seem to be properly elastic, and which are prone to produce "chattered" sections (Chapter 5.22) as well. However, this is not an invariable
effect by any means, and seems not to be a problem at all when "good"
lots of Epon are used (Fig. 10).
When efforts are made to use Epon sections for very high resolution
work, "grain" is apt to be evident, much more so, for example, than when
using comparable Araldite sections. This is not an important factor at
moderate magnifications (Fig. 10), and then its good contrast features
and relatively easy stainability recommend it.
4.12. Maraglas Embedding
Freeman and Spurlock (1962) introduced Maraglas 665 (Marblette
Corp., Long Island City, New York) as another epoxy resin that can be
used as a satisfactory embedment. As finally recommended by Spurlock,
Kattine, and Freeman (1963), they mix Maraglas 665, 68 ml, with the
hardener, Cardolite NC-513 (Minnesota Mining and Manufacturing Co.,
Newark, New Jersey), 20 ml, and the flexibilizer dibutyl phthalate, 10
ml. As an accelerator or curing agent, 2% benzyldimethylamine (Maume
Chemical Co., Toledo, Ohio) is used. Polymerization is carried out at
60°C for 24-48 hours.
There is no doubt that tissues successfully embedded in Maraglas secwith glass knives. Presumably it results from a disturbance or displacement of the
surface of the section as it is cut. It is as though the surface were scraped rather than
properly cleaved. Adhesive forces developing between components of this plastic embedment and the glass at the edge of the knife may be responsible, for apparently this
effect is never observed when diamond knives are used. The specimen was mammalian
skeletal muscle, fixed with Millonig's buffered osmium tetroxide, embedded in Epon,
and stained with alkaline lead hydroxide.
MARAGLAS EMBEDDING
115
is a "smudging" or "mottling" of the section as Fig. 11 illustrates. Interestingly enough, and perhaps informative, the effect is rarely if ever seen
when a diamond knife is employed, and yet may be unavoidable when
a glass knife is used. This would suggest that adhesive forces exist during
sectioning between some component of the block and glass. Because of
this it can be imagined that surface particles are dragged along as the
knife passes the block, or the section glides over the knife edge. Exactly
this is known to occur in many types of polishing actions. Indeed it is in
just this manner that a soft polishing agent like rouge can polish hard
steel. I have the impression that this effect is associated with blocks that
do not seem to be properly elastic, and which are prone to produce "chattered" sections (Chapter 5.22) as well. However, this is not an invariable
effect by any means, and seems not to be a problem at all when "good"
lots of Epon are used (Fig. 10).
When efforts are made to use Epon sections for very high resolution
work, "grain" is apt to be evident, much more so, for example, than when
using comparable Araldite sections. This is not an important factor at
moderate magnifications (Fig. 10), and then its good contrast features
and relatively easy stainability recommend it.
4.12. Maraglas Embedding
Freeman and Spurlock (1962) introduced Maraglas 665 (Marblette
Corp., Long Island City, New York) as another epoxy resin that can be
used as a satisfactory embedment. As finally recommended by Spurlock,
Kattine, and Freeman (1963), they mix Maraglas 665, 68 ml, with the
hardener, Cardolite NC-513 (Minnesota Mining and Manufacturing Co.,
Newark, New Jersey), 20 ml, and the flexibilizer dibutyl phthalate, 10
ml. As an accelerator or curing agent, 2% benzyldimethylamine (Maume
Chemical Co., Toledo, Ohio) is used. Polymerization is carried out at
60°C for 24-48 hours.
There is no doubt that tissues successfully embedded in Maraglas secwith glass knives. Presumably it results from a disturbance or displacement of the
surface of the section as it is cut. It is as though the surface were scraped rather than
properly cleaved. Adhesive forces developing between components of this plastic embedment and the glass at the edge of the knife may be responsible, for apparently this
effect is never observed when diamond knives are used. The specimen was mammalian
skeletal muscle, fixed with Millonig's buffered osmium tetroxide, embedded in Epon,
and stained with alkaline lead hydroxide.